Naval mine
Overview
 
A naval mine is a self-contained explosive device placed in water to destroy surface ship
Ship
Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...

s or submarine
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

s. Unlike depth charge
Depth charge
A depth charge is an anti-submarine warfare weapon intended to destroy or cripple a target submarine by the shock of exploding near it. Most use explosives and a fuze set to go off at a preselected depth in the ocean. Depth charges can be dropped by either surface ships, patrol aircraft, or from...

s, mines are deposited and left to wait until they are triggered by the approach of, or contact with, an enemy vessel. Naval mines can be used offensively—to hamper enemy shipping movements or lock vessels into a harbour; or defensively—to protect friendly vessels and create "safe" zones.

Mines can be laid in many ways: by purpose-built minelayer
Minelayer
Minelaying is the act of deploying explosive mines. Historically this has been carried out by ships, submarines and aircraft. Additionally, since World War I the term minelayer refers specifically to a naval ship used for deploying naval mines...

s, refitted ships, submarines, or aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

—and even by dropping them into a harbour by hand.
Unanswered Questions
Encyclopedia
A naval mine is a self-contained explosive device placed in water to destroy surface ship
Ship
Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...

s or submarine
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

s. Unlike depth charge
Depth charge
A depth charge is an anti-submarine warfare weapon intended to destroy or cripple a target submarine by the shock of exploding near it. Most use explosives and a fuze set to go off at a preselected depth in the ocean. Depth charges can be dropped by either surface ships, patrol aircraft, or from...

s, mines are deposited and left to wait until they are triggered by the approach of, or contact with, an enemy vessel. Naval mines can be used offensively—to hamper enemy shipping movements or lock vessels into a harbour; or defensively—to protect friendly vessels and create "safe" zones.

Mines can be laid in many ways: by purpose-built minelayer
Minelayer
Minelaying is the act of deploying explosive mines. Historically this has been carried out by ships, submarines and aircraft. Additionally, since World War I the term minelayer refers specifically to a naval ship used for deploying naval mines...

s, refitted ships, submarines, or aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

—and even by dropping them into a harbour by hand. They can be inexpensive: some variants can cost as little as US$
United States dollar
The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....

1000, though more sophisticated mines can cost millions of dollars, be equipped with several kinds of sensors, and deliver a warhead
Warhead
The term warhead refers to the explosive material and detonator that is delivered by a missile, rocket, or torpedo.- Etymology :During the early development of naval torpedoes, they could be equipped with an inert payload that was intended for use during training, test firing and exercises. This...

 by rocket
Rocket
A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...

 or torpedo
Torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

.

Their flexibility and cost-effectiveness make mines attractive to the less powerful belligerent in asymmetric warfare
Asymmetric warfare
Asymmetric warfare is war between belligerents whose relative military power differs significantly, or whose strategy or tactics differ significantly....

. The cost of producing and laying a mine is usually anywhere from 0.5% to 10% of the cost of removing it, and it can take up to 200 times as long to clear a minefield as to lay it. Parts of some World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 naval minefields still exist because they are too extensive and expensive to clear. It is possible for some of these 1940s-era mines to remain dangerous for many years to come.

Mines have been employed as offensive or defensive weapons in rivers, lakes, estuaries, seas, and oceans, but they can also be used as tools of psychological warfare
Psychological warfare
Psychological warfare , or the basic aspects of modern psychological operations , have been known by many other names or terms, including Psy Ops, Political Warfare, “Hearts and Minds,” and Propaganda...

. Offensive mines are placed in enemy waters, outside harbours and across important shipping routes with the aim of sinking both merchant and military vessels. Defensive minefields safeguard key stretches of coast from enemy ships and submarines, forcing them into more easily-defended areas, or keeping them away from sensitive ones.

Minefields designed for psychological effect are usually placed on trade route
Trade route
A trade route is a logistical network identified as a series of pathways and stoppages used for the commercial transport of cargo. Allowing goods to reach distant markets, a single trade route contains long distance arteries which may further be connected to several smaller networks of commercial...

s and are used to stop shipping reaching an enemy nation. They are often spread thin, to create an impression of minefields existing across large areas. A single mine inserted strategically on a shipping route can stop maritime movements for days while the entire area is swept.

International law
International law
Public international law concerns the structure and conduct of sovereign states; analogous entities, such as the Holy See; and intergovernmental organizations. To a lesser degree, international law also may affect multinational corporations and individuals, an impact increasingly evolving beyond...

 requires nations to declare when they mine an area, in order to make it easier for civil shipping to avoid the mines. The warnings do not have to be specific; during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, Britain declared simply that it had mined the English Channel
English Channel
The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...

, North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

, and French coast.

Early use

The precursor to naval mines was first described by the early Ming Dynasty
Ming Dynasty
The Ming Dynasty, also Empire of the Great Ming, was the ruling dynasty of China from 1368 to 1644, following the collapse of the Mongol-led Yuan Dynasty. The Ming, "one of the greatest eras of orderly government and social stability in human history", was the last dynasty in China ruled by ethnic...

 Chinese artillery
Artillery
Originally applied to any group of infantry primarily armed with projectile weapons, artillery has over time become limited in meaning to refer only to those engines of war that operate by projection of munitions far beyond the range of effect of personal weapons...

 officer Jiao Yu
Jiao Yu
Jiao Yu was a Chinese military officer loyal to Zhu Yuanzhang , the founder of the Ming Dynasty . He was entrusted by Emperor Hongwu as a leading artillery officer for the rebel army that overthrew the Mongol Yuan Dynasty, and established the Ming Dynasty...

, in his 14th century military treatise known as the Huolongjing
Huolongjing
The Huolongjing is a 14th century military treatise that was compiled and edited by Jiao Yu and Liu Ji of the early Ming Dynasty in China...

. Chinese records tell of naval explosives in the 16th century, used to fight against Japanese pirates (Wokou
Wokou
Wokou , which literally translates as "Japanese pirates" in English, were pirates of varying origins who raided the coastlines of China and Korea from the 13th century onwards...

). This kind of naval mine was loaded in a wooden box, sealed by putty
Putty
Putty is a generic term for a plastic material similar in texture to clay or dough typically used in domestic construction and repair as a sealant or filler. Painter's Putty is typically a linseed oil based product used for filling holes, minor cracks and defacements in wood only...

. General Qi Jiguang
Qi Jiguang
Qi Jiguang was a Chinese military general and national hero during the Ming Dynasty. He was best remembered for his courage and leadership in the fight against Japanese pirates along the east coast of China, as well as his reinforcement work on the Great Wall of China.-Early life:Qi Jiguang was...

 made several timed, drifting explosives to harass Japanese pirate ships. However, in the Tiangong Kaiwu ('The Exploitation of the Works of Nature') treatise, written by Song Yingxing
Song Yingxing
Song Yingxing , born in Yichun of Jiangxi, was a Chinese scientist and encyclopedist who lived during the late Ming Dynasty . He was the author of an encyclopedia that covered a wide variety of technical subjects, including the use of gunpowder weapons...

 in 1637 AD, it describes naval mines with a rip cord pulled by hidden ambushers located on the nearby shore who rotated a steel wheellock
Wheellock
A wheellock, wheel-lock or wheel lock, is a friction-wheel mechanism to cause a spark for firing a firearm. It was the next major development in firearms technology after the matchlock and the first self-igniting firearm. The mechanism is so-called because it uses a rotating steel wheel to provide...

 flint mechanism to produce sparks and ignite the fuse of the naval mine. Although this is the rotating steel wheellock's first use with naval mines, Jiao Yu had described their use for land mine
Land mine
A land mine is usually a weight-triggered explosive device which is intended to damage a target—either human or inanimate—by means of a blast and/or fragment impact....

s back in the 14th century.

The first plan for a sea mine in the West was by Ralph Rabbards, who presented his design to Queen Elizabeth I of England
Elizabeth I of England
Elizabeth I was queen regnant of England and Ireland from 17 November 1558 until her death. Sometimes called The Virgin Queen, Gloriana, or Good Queen Bess, Elizabeth was the fifth and last monarch of the Tudor dynasty...

 in 1574. The Dutch inventor Cornelius Drebbel
Cornelius Drebbel
Cornelis Jacobszoon Drebbel was the Dutch builder of the first navigable submarine in 1620. Drebbel was an innovator who contributed to the development of measurement and control systems, optics and chemistry....

 was employed in the Office of Ordnance by King Charles I of England to make weapons, including a "floating petard" which proved a failure. Weapons of this type were apparently tried by the English at the Siege of La Rochelle
Siege of La Rochelle
The Siege of La Rochelle was a result of a war between the French royal forces of Louis XIII of France and the Huguenots of La Rochelle in 1627-1628...

 in 1627.

American David Bushnell
David Bushnell
David Bushnell , of Westbrook, Connecticut, was an American inventor during the Revolutionary War. He is credited with creating the first submarine ever used in combat, while studying at Yale University in 1775. He called it the Turtle because of its look in the water...

 invented the first practical mine, for use against the British in the American War of Independence. It was a watertight keg filled with gunpowder
Gunpowder
Gunpowder, also known since in the late 19th century as black powder, was the first chemical explosive and the only one known until the mid 1800s. It is a mixture of sulfur, charcoal, and potassium nitrate - with the sulfur and charcoal acting as fuels, while the saltpeter works as an oxidizer...

 that was floated toward the enemy, detonated by a sparking mechanism if it struck a ship. It was used on the Delaware River
Delaware River
The Delaware River is a major river on the Atlantic coast of the United States.A Dutch expedition led by Henry Hudson in 1609 first mapped the river. The river was christened the South River in the New Netherland colony that followed, in contrast to the North River, as the Hudson River was then...

 as a drift mine, and was regarded as unethical.

19th century

In 1812 Russian engineer Pavel Shilling exploded an underwater mine using an electrical circuit. In 1854, during the unsuccessful attempt of the Anglo-French fleet to seize Kronshtadt fortress, British steamships HMS Merlin (9 June 1855, the first successful mining in history), HMS Vulture and HMS Firefly were damaged by underwater explosions of Russian naval mines. More than 1500 naval mines, or infernal machines, designed by Moritz von Jacobi and Alfred Nobel
Alfred Nobel
Alfred Bernhard Nobel was a Swedish chemist, engineer, innovator, and armaments manufacturer. He is the inventor of dynamite. Nobel also owned Bofors, which he had redirected from its previous role as primarily an iron and steel producer to a major manufacturer of cannon and other armaments...

 were set by Russian naval specialists in the Gulf of Finland
Gulf of Finland
The Gulf of Finland is the easternmost arm of the Baltic Sea. It extends between Finland and Estonia all the way to Saint Petersburg in Russia, where the river Neva drains into it. Other major cities around the gulf include Helsinki and Tallinn...

 during the Crimean War
Crimean War
The Crimean War was a conflict fought between the Russian Empire and an alliance of the French Empire, the British Empire, the Ottoman Empire, and the Kingdom of Sardinia. The war was part of a long-running contest between the major European powers for influence over territories of the declining...

. The mining of Vulcan led to the worlds first minesweeping operation. During the next 72 hours, 33 mines were swept.

The American Civil War
American Civil War
The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...

 also saw the successful use of mines. The first ship sunk by a mine was the USS Cairo
USS Cairo (1861)
USS Cairo was a City class ironclad gunboat constructed for the Union Navy by James B. Eads during the American Civil War. She was the first vessel of the City class ironclads, also called the Cairo class....

 in 1862 in the Yazoo River
Yazoo River
The Yazoo River is a river in the U.S. state of Mississippi.The Yazoo River was named by French explorer La Salle in 1682 as "Rivière des Yazous" in reference to the Yazoo tribe living near the river's mouth. The exact meaning of the term is unclear...

. Rear Admiral
Rear Admiral
Rear admiral is a naval commissioned officer rank above that of a commodore and captain, and below that of a vice admiral. It is generally regarded as the lowest of the "admiral" ranks, which are also sometimes referred to as "flag officers" or "flag ranks"...

 David Farragut
David Farragut
David Glasgow Farragut was a flag officer of the United States Navy during the American Civil War. He was the first rear admiral, vice admiral, and admiral in the United States Navy. He is remembered in popular culture for his order at the Battle of Mobile Bay, usually paraphrased: "Damn the...

's famous statement, "Damn the torpedoes, full speed ahead!" refers to a minefield laid at Mobile, Alabama
Mobile, Alabama
Mobile is the third most populous city in the Southern US state of Alabama and is the county seat of Mobile County. It is located on the Mobile River and the central Gulf Coast of the United States. The population within the city limits was 195,111 during the 2010 census. It is the largest...

.

In the 19th century, mines were called torpedo
Torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

es, a name probably conferred by Dennis Fletcher after the torpedo fish, which gives powerful electric shock
Electric shock
Electric Shock of a body with any source of electricity that causes a sufficient current through the skin, muscles or hair. Typically, the expression is used to denote an unwanted exposure to electricity, hence the effects are considered undesirable....

s. A spar torpedo
Spar torpedo
A spar torpedo is a weapon consisting of a bomb placed at the end of a long pole, or spar, and attached to a boat. The weapon is used by running the end of the spar into the enemy ship. Spar torpedoes were often equipped with a barbed spear at the end, so it would stick to wooden hulls...

 was a mine attached to a long pole and detonated when the ship carrying it rammed another one. The H. L. Hunley
H. L. Hunley (submarine)
H. L. Hunley was a submarine of the Confederate States of America that played a small part in the American Civil War, but a large role in the history of naval warfare. The Hunley demonstrated both the advantages and the dangers of undersea warfare...

used one to sink the USS Housatonic
USS Housatonic (1861)
The first USS Housatonic was a screw sloop-of-war of the United States Navy, named for the Housatonic River of New England which rises in Berkshire County, Massachusetts, and flows southward into Connecticut before emptying into Long Island Sound a little east of Bridgeport, Connecticut...

 on February 17, 1864. A Harvey Torpedo was a type of floating mine towed alongside a ship, and was briefly in service in the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 in the 1870s. Other "torpedoes" attached to ships or propelled themselves. One such weapon, called the Whitehead torpedo after its inventor, caused the word "torpedo" to be used for self-propelled underwater missiles rather than static devices.

Early 20th century

During the Boxer Rebellion
Boxer Rebellion
The Boxer Rebellion, also called the Boxer Uprising by some historians or the Righteous Harmony Society Movement in northern China, was a proto-nationalist movement by the "Righteous Harmony Society" , or "Righteous Fists of Harmony" or "Society of Righteous and Harmonious Fists" , in China between...

, Imperial Chinese forces deployed a weapon called "electric mines" on June 15, at the Peiho river before the Battle of Dagu Forts (1900), to prevent the western Eight-Nation Alliance
Eight-Nation Alliance
The Eight-Nation Alliance was an alliance of Austria-Hungary, France, Germany, Italy, Japan, Russia, the United Kingdom, and the United States whose military forces intervened in China to suppress the anti-foreign Boxers and relieve the siege of the diplomatic legations in Beijing .- Events :The...

 from sending ships to attack. This was reported by American military intelligence in the United States. War Dept. by the United States. Adjutant-General's Office. Military Information Division.

The next major use of mines was during the Russo-Japanese War
Russo-Japanese War
The Russo-Japanese War was "the first great war of the 20th century." It grew out of rival imperial ambitions of the Russian Empire and Japanese Empire over Manchuria and Korea...

 of 1904-1905. They proved their worth as weapons in this conflict. For instance, two mines blew up when the Russian battleship
Battleship
A battleship is a large armored warship with a main battery consisting of heavy caliber guns. Battleships were larger, better armed and armored than cruisers and destroyers. As the largest armed ships in a fleet, battleships were used to attain command of the sea and represented the apex of a...

 Petropavlovsk
Russian battleship Petropavlovsk (1897)
The Petropavlovsk was the lead ship of the Petropavlovsk class of battleships built for the Imperial Russian Navy. During the Russo-Japanese War, Petropavlovsk was a flagship of the First Pacific Squadron, taking part in battles against the Imperial Japanese Navy. On March 31, 1904, the battleship...

 struck them near Port Arthur, sending the holed vessel to the bottom and killing the fleet commander, Admiral Stepan Makarov
Stepan Makarov
Stepan Osipovich Makarov was a Ukrainian - born Russian vice-admiral, a highly accomplished and decorated commander of the Imperial Russian Navy, an oceanographer, awarded by the Russian Academy of Sciences, and author of several books. Makarov also designed a small number of ships...

, and most of her crew in the process. The toll inflicted by mines was not confined to the Russians, however. The Japanese Navy
Imperial Japanese Navy
The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...

 lost two battleships, four cruisers, two destroyers and a torpedo-boat to offensively laid mines during the war. Most famously, on May 15, 1904, the Russian minelayer
Minelayer
Minelaying is the act of deploying explosive mines. Historically this has been carried out by ships, submarines and aircraft. Additionally, since World War I the term minelayer refers specifically to a naval ship used for deploying naval mines...

 Amur planted a 50-mine minefield off Port Arthur and succeeded in sinking the Japanese battleships Hatsuse
Japanese battleship Hatsuse
|-External links:**...

 and Yashima
Japanese battleship Yashima
|-External links:** The New York Times, June 2, 1905....

.

Many early mines were fragile and dangerous to handle, as they contained glass containers filled with nitroglycerin or mechanical devices that activated a blast upon tipping. Several mine-laying ships were destroyed when their cargo exploded.

Beginning at the turn of the century, submarine mines played a major role in the defense of U.S. harbors
Submarine mines in U.S. harbor defense
The modern era of defending American harbors with submarine mines began in the post-Civil War period.In 1866, the U.S. [Army] Corps of Engineers established the Engineer School of Application at Willets Point, NY. The first commander of this School, Maj...

 against enemy attack. The mines employed were controlled mines, anchored to the bottoms of the harbors and detonated under control from large mine casemates on shore.

During World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

, mines were used extensively to defend coasts, coastal shipping, ports and naval bases around the globe. The Germans laid mines in shipping lanes to sink merchant and naval vessels serving Britain. The Allies targeted the German U-boats in the Strait of Dover and the Hebrides. In an attempt to seal up the northern exits of the North Sea, the Allies developed the North Sea Mine Barrage. During a period of five months from June almost 70,000 mines were laid spanning the North Sea's northern exits. The total number of mines laid in the North Sea, the British East Coast, Straits of Dover, and Heligoland Bight is estimated at 190,000 and the total number during the whole of WWI was 235,000 sea mines. Clearing the barrage after the war took 82 ships and 5 months, working around the clock.

World War II

During World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, the U-boat
U-boat
U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...

 fleet, which dominated much of the battle of the Atlantic, was small at the beginning of the war and much of the early action by German forces involved mining convoy
Convoy
A convoy is a group of vehicles, typically motor vehicles or ships, traveling together for mutual support and protection. Often, a convoy is organized with armed defensive support, though it may also be used in a non-military sense, for example when driving through remote areas.-Age of Sail:Naval...

 routes and ports around Britain. German submarines also operated in the Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...

, in the Caribbean Sea
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....

, and along the U.S. coast.

Initially, contact mines—requiring a ship physically strike a mine to detonate it—were employed, usually tethered at the end of a cable just below the surface of the water. Contact mines usually hole ships’ hulls. By the beginning of World War II, most nations had developed mines that could be dropped from aircraft and floated on the surface, making it possible to lay them in enemy harbours. The use of dredging and nets was effective against this type of mine, but this consumed time and resources, and required harbours to be closed.

Later, some ships survived mine blasts, limping into port with buckled plates and broken backs. This appeared to be due to a new type of mine, detecting ships magnetically and detonating at a distance, causing damage with the shock wave of the explosion. Ships that had successfully run the gauntlet of the Atlantic crossing were sometimes destroyed entering freshly cleared British harbours. More shipping was being lost than could be replaced, and Churchill
Winston Churchill
Sir Winston Leonard Spencer-Churchill, was a predominantly Conservative British politician and statesman known for his leadership of the United Kingdom during the Second World War. He is widely regarded as one of the greatest wartime leaders of the century and served as Prime Minister twice...

 ordered the intact recovery of one of these new mines was of the highest priority.

The British experienced a stroke of luck in November 1939. A German mine was dropped from an aircraft onto the mud flats of the Thames estuary
Thames Estuary
The Thames Mouth is the estuary in which the River Thames meets the waters of the North Sea.It is not easy to define the limits of the estuary, although physically the head of Sea Reach, near Canvey Island on the Essex shore is probably the western boundary...

 during low tide. As if this was not sufficiently good fortune, the land belonged to the army, and a base with men and workshops was at hand. Experts were dispatched from London to investigate the mine. They had some idea that the mines used magnetic sensors, so everyone removed all metal, including their buttons, and made tools of non-magnetic brass. They disarmed the mine and rushed it to labs at Portsmouth
Portsmouth
Portsmouth is the second largest city in the ceremonial county of Hampshire on the south coast of England. Portsmouth is notable for being the United Kingdom's only island city; it is located mainly on Portsea Island...

, where scientists discovered a new type of arming mechanism. A large ferrous object passing through the Earth's magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...

 will concentrate the field through it; the mine's detector was designed to trigger at the mid-point of a steel-hulled ship passing overhead. The mechanism had an adjustable sensitivity, calibrated in milligauss
Gauss (unit)
The gauss, abbreviated as G, is the cgs unit of measurement of a magnetic field B , named after the German mathematician and physicist Carl Friedrich Gauss. One gauss is defined as one maxwell per square centimeter; it equals 1 tesla...

. (As it turned out, the German firing mechanism was overly sensitive, making sweeping easier.) The U.S. began adding delay counters to their magnetic mines in June 1945.

From these data, methods were developed to clear the mines. Early methods included the use of large electromagnets dragged behind ships or below low-flying aircraft (a number of older bombers like the Vickers Wellington
Vickers Wellington
The Vickers Wellington was a British twin-engine, long range medium bomber designed in the mid-1930s at Brooklands in Weybridge, Surrey, by Vickers-Armstrongs' Chief Designer, R. K. Pierson. It was widely used as a night bomber in the early years of the Second World War, before being displaced as a...

 were used for this). Both of these methods had the disadvantage of "sweeping" only a small strip. A better solution was found in the "Double-L Sweep" using electrical cables dragged behind ships that passed large pulses of current through the seawater. This induced a large magnetic field and swept the entire area between the two ships. The older methods continued to be used in smaller areas. The Suez Canal
Suez Canal
The Suez Canal , also known by the nickname "The Highway to India", is an artificial sea-level waterway in Egypt, connecting the Mediterranean Sea and the Red Sea. Opened in November 1869 after 10 years of construction work, it allows water transportation between Europe and Asia without navigation...

 continued to be swept by aircraft, for instance. Wartime Japanese sweep methods, by contrast, never advanced much past 1930s standards, and failed entirely to keep up with new American mines, clearing no more than 15% of all the mines laid in Japan's coastal waters. Moreover, IJN's minesweeping force was derisively small, only 350 ships, numbering 20,000 men.

While these methods were useful for clearing mines from local ports, they were of little or no use for enemy-controlled areas. These were typically visited by warships, and the majority of the fleet then underwent a massive degaussing process, where their hulls had a slight "south" bias induced into them which offset the concentration effect almost to zero.

Initially, major warships and large troopships had a copper degaussing coil fitted around the perimeter of the hull, energized by the ship's electrical system whenever in suspected magnetic-mined waters. Some of the first to be so-fitted were the carrier
Aircraft carrier
An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...

 HMS Ark Royal and the liners and , which were used as troopships. This was felt to be impracticable for the myriad of smaller warships and merchant vessels, not least due to the amount of copper that would be required. It was found that "wiping" a current-carrying cable up and down a ship' hull temporarily cancelled the ships' magnetic signature sufficiently to nullify the threat. This started in late 1939, and by 1940 merchant vessels and the smaller British warships were largely immune for a few months at a time until they once again built up a field. Many of the boats that sailed to Dunkirk
Battle of Dunkirk
The Battle of Dunkirk was a battle in the Second World War between the Allies and Germany. A part of the Battle of France on the Western Front, the Battle of Dunkirk was the defence and evacuation of British and allied forces in Europe from 26 May–4 June 1940.After the Phoney War, the Battle of...

 were degaussed in a marathon four day effort by degaussing stations.

The Allies deployed acoustic mines, against which even wooden-hull
Hull (watercraft)
A hull is the watertight body of a ship or boat. Above the hull is the superstructure and/or deckhouse, where present. The line where the hull meets the water surface is called the waterline.The structure of the hull varies depending on the vessel type...

ed ships (in particular minesweeper
Minesweeper (ship)
A minesweeper is a small naval warship designed to counter the threat posed by naval mines. Minesweepers generally detect then neutralize mines in advance of other naval operations.-History:...

s) remained vulnerable. Japan developed sonic generators to sweep these; the gear was not ready by war's end. The primary method Japan used was small air-delivered bombs. This was profligate and ineffectual; used against acoustic mines at Penang
Penang
Penang is a state in Malaysia and the name of its constituent island, located on the northwest coast of Peninsular Malaysia by the Strait of Malacca. It is bordered by Kedah in the north and east, and Perak in the south. Penang is the second smallest Malaysian state in area after Perlis, and the...

, she needed 200 bombs to detonate just 13 mines.

The Germans had also developed a pressure-activated mine and planned to deploy it as well, but they saved it for later use when it became clear the British had defeated the magnetic system. The U.S. also deployed these, adding "counters" which would allow a variable number of ships to pass unharmed before detonating. This made them a great deal harder to sweep. Japan's antiquated sweep methods, lifting mines in nets, accidentally proved useful against these mines; it remained too slow and hazardous to be truly effective, especially in light of the high numbers being laid.

Mining campaigns could have devastating consequences. The U.S. effort against Japan, for instance, closed major ports, such as Hiroshima
Hiroshima
is the capital of Hiroshima Prefecture, and the largest city in the Chūgoku region of western Honshu, the largest island of Japan. It became best known as the first city in history to be destroyed by a nuclear weapon when the United States Army Air Forces dropped an atomic bomb on it at 8:15 A.M...

, for days, and by the end of the Pacific War had cut the amount of freight passing through Kobe
Kobe
, pronounced , is the fifth-largest city in Japan and is the capital city of Hyōgo Prefecture on the southern side of the main island of Honshū, approximately west of Osaka...

Yokohama
Yokohama
is the capital city of Kanagawa Prefecture and the second largest city in Japan by population after Tokyo and most populous municipality of Japan. It lies on Tokyo Bay, south of Tokyo, in the Kantō region of the main island of Honshu...

 by 90%.

When the war ended, more than 25,000 U.S.-laid mines were still in place, and the Navy proved unable to sweep them all, limiting efforts to critical areas. After sweeping for almost a year, in May 1946, the Navy abandoned the effort with 13,000 mines still unswept. Over the next thirty years, more than 500 minesweepers (of a variety of types) were damaged or sunk in continuing clearance efforts.

Cold War era

Since World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, mines have damaged 14 United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 ships, whereas air and missile attacks have damaged four. During the Korean War
Korean War
The Korean War was a conventional war between South Korea, supported by the United Nations, and North Korea, supported by the People's Republic of China , with military material aid from the Soviet Union...

, mines laid by North Korean forces caused 70% of the damage suffered by U.S. naval vessels and caused 4 sinkings.

During the Iran–Iraq War from 1980 to 1988, the belligerents mined several areas of the Persian Gulf
Persian Gulf
The Persian Gulf, in Southwest Asia, is an extension of the Indian Ocean located between Iran and the Arabian Peninsula.The Persian Gulf was the focus of the 1980–1988 Iran-Iraq War, in which each side attacked the other's oil tankers...

 and nearby waters. On April 14, 1988, the USS Samuel B. Roberts (FFG-58)
USS Samuel B. Roberts (FFG-58)
USS Samuel B. Roberts is one of the final ships in the United States Navy's Oliver Hazard Perry class of guided missile frigates . The ship was severely damaged by an Iranian mine in 1988, leading U.S. forces to respond with Operation Praying Mantis.-Commissioning and namesake:The frigate was...

 struck an Iranian M-08/39 mine in the central Persian Gulf
Persian Gulf
The Persian Gulf, in Southwest Asia, is an extension of the Indian Ocean located between Iran and the Arabian Peninsula.The Persian Gulf was the focus of the 1980–1988 Iran-Iraq War, in which each side attacked the other's oil tankers...

 shipping lane, wounding 10 sailors.

In the summer of 1984, magnetic sea mines damaged at least 19 ships in the Red Sea
Red Sea
The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...

. The U.S. concluded Libya
Libya
Libya is an African country in the Maghreb region of North Africa bordered by the Mediterranean Sea to the north, Egypt to the east, Sudan to the southeast, Chad and Niger to the south, and Algeria and Tunisia to the west....

 was probably responsible for the minelaying. In response the U.S., Britain, France, and three other nations launched Operation Intense Look, a minesweeping operation in the Red Sea involving more than 46 ships.

On the orders of the Reagan administration
Reagan Administration
The United States presidency of Ronald Reagan, also known as the Reagan administration, was a Republican administration headed by Ronald Reagan from January 20, 1981, to January 20, 1989....

, the CIA mined Nicaragua
Nicaragua
Nicaragua is the largest country in the Central American American isthmus, bordered by Honduras to the north and Costa Rica to the south. The country is situated between 11 and 14 degrees north of the Equator in the Northern Hemisphere, which places it entirely within the tropics. The Pacific Ocean...

's Sandino
Puerto Sandino
Puerto Sandino is a coastal town in western Nicaragua. It is located at around .- U.S. Attacks :While supporting the Contras in the 1980s, U.S. forces attacked Puerto Sandino on September 13 and October 14, 1983. On March 28 and March 30, 1984 U.S. forces attacked patrol boats at Puerto Sandino....

 port in 1984 in support of the Contra
Contras
The contras is a label given to the various rebel groups opposing Nicaragua's FSLN Sandinista Junta of National Reconstruction government following the July 1979 overthrow of Anastasio Somoza Debayle's dictatorship...

 guerrilla group. A Soviet tanker was among the ships damaged by these mines. In 1986, in the case of Nicaragua v. United States, the International Court of Justice
International Court of Justice
The International Court of Justice is the primary judicial organ of the United Nations. It is based in the Peace Palace in The Hague, Netherlands...

 ruled that this mining was a violation of international law.

During the Gulf War
Gulf War
The Persian Gulf War , commonly referred to as simply the Gulf War, was a war waged by a U.N.-authorized coalition force from 34 nations led by the United States, against Iraq in response to Iraq's invasion and annexation of Kuwait.The war is also known under other names, such as the First Gulf...

, Iraq
Iraq
Iraq ; officially the Republic of Iraq is a country in Western Asia spanning most of the northwestern end of the Zagros mountain range, the eastern part of the Syrian Desert and the northern part of the Arabian Desert....

i naval mines severely damaged USS Princeton (CG-59)
USS Princeton (CG-59)
USS Princeton is a guided missile cruiser serving in the United States Navy. Armed with naval guns and anti-air, anti-surface, and anti-submarine missiles, plus other weapons, she is equipped for surface-to-air, surface-to-surface, and anti-submarine warfare. She also is the home of two Seahawk...

 and USS Tripoli (LPH-10)
USS Tripoli (LPH-10)
USS Tripoli , an , was laid down on 15 June 1964 at Pascagoula, Mississippi, by the Ingalls Shipbuilding Corporation; launched on 31 July 1965; sponsored by Mrs. Jane Cates, the wife of General Clifton B. Cates, former Commandant of the Marine Corps; and commissioned on 6 August 1966 at the...

. When the war concluded, eight countries conducted clearance operations.

Types

Naval mines may be classified into two major groups.

Contact mines

The earliest mines were usually of this type. They are still used today, as they are extremely low cost compared to any other anti-ship weapon and are effective, both as a terror weapon and to sink enemy ships. Contact mines need to be touched by the target before they detonate, limiting the damage to the direct effects of the explosion and usually affecting only the single vessel that triggers them.

Early mines had mechanical mechanisms to detonate them, but these were superseded in the 1870s by the Hertz Horn (or chemical horn), which was found to work reliably even after the mine had been in the sea for several years. The mine's upper half is studded with hollow lead protuberances, each containing a glass vial filled with sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

. When a ship's hull crushes the metal horn, it cracks the vial inside it, allowing the acid to run down a tube and into a lead-acid battery
Battery (electricity)
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...

 which until then contains no acid electrolyte. This energizes the battery, which detonates the explosive.

Earlier forms of the detonator used a vial filled with sulfuric acid, surrounded by a mixture of potassium perchlorate
Potassium perchlorate
Potassium perchlorate is the inorganic salt with the chemical formula KClO4. Like other perchlorates, this salt is a strong oxidizer and potentially reacts with many organic substances...

 and sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...

. When the vial was crushed, the acid ignited the perchlorate-sugar mix, and the resulting flame ignited the gunpowder charge.

During the initial period of World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

, the British Navy used contact mines in the English Channel
English Channel
The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...

 and later in large areas of the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

 to hinder patrols by German submarine
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

s. Later, the American antenna mine was widely used because submarines could be at any depth from the surface to the seabed. This type of mine had a copper wire attached to a buoy that floated above the explosive charge which was weighted to the seabed with a steel cable. If a submarine's steel hull touched the copper wire, the slight voltage change caused by contact between two dissimilar metals was amplified and detonated the explosives.

Limpet mines

Limpet mines are a special form of contact mine which are attached to the target by magnets and left, and are so named because of the superficial similarity to the limpet
Limpet
Limpet is a common name for a number of different kinds of saltwater and freshwater snails ; it is applied to those snails that have a simple shell which is more or less conical in shape, and either is not spirally coiled, or appears not to be coiled in the adult snails.The name limpet is most...

, a mollusk.

Moored contact mines

Generally, this mine type is set to float just below the surface of the water or as deep as five meters. A steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 cable connecting the mine to an anchor
Anchor
An anchor is a device, normally made of metal, that is used to connect a vessel to the bed of a body of water to prevent the vessel from drifting due to wind or current. The word derives from Latin ancora, which itself comes from the Greek ἄγκυρα .Anchors can either be temporary or permanent...

 on the seabed prevents it from drifting away. The explosive and detonating mechanism is contained in a buoyant metal or plastic shell. The depth below the surface at which the mine floats can be set so that only deep draft vessels such as aircraft carriers, battleships or large cargo ships are at risk, saving the mine from being used on a less valuable target. In littoral
Littoral
The littoral zone is that part of a sea, lake or river that is close to the shore. In coastal environments the littoral zone extends from the high water mark, which is rarely inundated, to shoreline areas that are permanently submerged. It always includes this intertidal zone and is often used to...

 waters it is important to ensure that the mine does not become visible when the sea level falls at low tide, so the cable length is adjusted to take account of tides. Even during the Second World War, there were mines that could be moored in 300m-deep water (Example: The U.S. Mark 6).

Floating mines typically have a mass of around 200 kg, including 80 kg of explosives e.g. TNT, minol
Minol (explosive)
Minol is a military explosive developed by the Admiralty early in the Second World War to augment supplies of Trinitrotoluene and RDX, which were then in short supply. The aluminium component in Minol significantly prolongs the explosive pulse, making it ideal for use in underwater naval weapons...

 or amatol
Amatol
Amatol is a highly explosive material made from a mixture of TNT and ammonium nitrate. Its name originates from the words ammonium and toluene...

.

During WWII mine traps were used for blocking port entrances. Two floating mines were anchored some distance apart on either side of a shipping channel, linked by a chain. When a deep draft vessel passed through the trap it would pull the chain along with it, dragging the mines onto the sides of the ship; the resulting double explosion often sank it. This system was not used extensively, but proved effective in blocking ports.

Drifting contact mines

Drifting mines were occasionally used during World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

 and World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. However, they were more feared than effective. Sometimes floating mines break from their moorings and become drifting mines; modern mines are designed to deactivate in this event. After several years at sea, the deactivation mechanism might not function as intended and the mines may remain live. Admiral Jellicoe
John Jellicoe, 1st Earl Jellicoe
Admiral of the Fleet John Rushworth Jellicoe, 1st Earl Jellicoe, GCB, OM, GCVO was a British Royal Navy admiral who commanded the Grand Fleet at the Battle of Jutland in World War I...

's British fleet did not pursue and destroy the outnumbered German High Seas Fleet when it turned away at the Battle of Jutland
Battle of Jutland
The Battle of Jutland was a naval battle between the British Royal Navy's Grand Fleet and the Imperial German Navy's High Seas Fleet during the First World War. The battle was fought on 31 May and 1 June 1916 in the North Sea near Jutland, Denmark. It was the largest naval battle and the only...

 because he thought they were leading him into a trap: he believed it possible that the Germans were either leaving floating mines in their wake, or were drawing him towards submarines, although neither of these was the case.

Churchill promoted "Operation Royal Marine" in 1940 and again in 1944 where floating mines were put into the Rhine in France to float down the river, becoming active after a time calculated to be long enough to reach German territory.

After World War I the drifting contact mine was banned, but was occasionally used during World War II. The drifting mines were much harder to remove than tethered mines after the war, and they caused about the same damage to both sides.

Bottom contact mines

A bottom contact mine is the simplest form of mine. It is merely an explosive charge with some form of fuze
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...

 fitted lying on the seafloor. They have been used against submarines, as submarines sometimes lie on the seafloor to reduce their acoustic signature. They are also used to prevent landing craft from reaching the shore and were a major obstacle during the D-Day landings. The Germans used antitank mines here with minor modifications to make them more reliable underwater, attaching the mines to the front of many of the obstacles seen in photos of the landing.

These mines usually weighed 2 to 50 kg, including 1 to 40 kg of explosives (TNT or hexatonal
RDX
RDX, an initialism for Research Department Explosive, is an explosive nitroamine widely used in military and industrial applications. It was developed as an explosive which was more powerful than TNT, and it saw wide use in WWII. RDX is also known as cyclonite, hexogen , and T4...

).

Remotely controlled mines

Frequently used in combination with coastal artillery and hydrophones, controlled mines
Controlled mines
A Controlled Mine was a circuit fired weapon used in coastal defenses with ancestry going back to 1805 when Robert Fulton termed his underwater explosive device a torpedo:...

 (or command detonation mines) can be in place in peacetime, which is a huge advantage in blocking important shipping routes. The mines can usually be turned into "normal" mines with a switch (which prevents the enemy from simply capturing the controlling station and deactivating the mines), detonated on a signal or be allowed to detonate on their own. The earliest ones were developed around 1812 by Robert Fulton
Robert Fulton
Robert Fulton was an American engineer and inventor who is widely credited with developing the first commercially successful steamboat...

. The first remotely controlled mines were moored mines used in the American Civil War
American Civil War
The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...

, detonated electrically from shore. They were considered superior to contact mines because they did not put friendly shipping at risk.

Modern examples usually weigh 200 kg (440 lb), including 80 kg (175 lb) of explosives (TNT or hexatonal).

Influence mines

These mines are triggered by the influence of a ship or submarine, rather than direct contact. Such mines incorporate electronic
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...

 sensors designed to detect the presence of a vessel and detonate when it comes within the blast
Explosion
An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...

 range of the warhead
Warhead
The term warhead refers to the explosive material and detonator that is delivered by a missile, rocket, or torpedo.- Etymology :During the early development of naval torpedoes, they could be equipped with an inert payload that was intended for use during training, test firing and exercises. This...

. The fuze
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...

s on such mines may incorporate one or more of the following sensors: magnetic, passive acoustic
Acoustic signature
Acoustic signature is used to describe a combination of acoustic emissions of ships and submarines.-Contributing factors:The acoustic signature is made up of a number of individual elements...

 or water pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

 displacement caused by the proximity of a vessel.

First used during the First World War, their use became more general in the Second World War. The sophistication of influence mine fuze
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...

s has increased considerably over the years as first transistor
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...

s and then microprocessor
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...

s have been incorporated into designs. Simple magnetic sensors have been superseded by total-field magnetometer
Magnetometer
A magnetometer is a measuring instrument used to measure the strength or direction of a magnetic field either produced in the laboratory or existing in nature...

s. Whereas early magnetic mine fuzes would respond only to changes in a single component of a target vessel's magnetic field, a total field magnetometer responds to changes in the magnitude of the total background field (thus enabling it to better detect even degaussed ships). Similarly, the original broadband hydrophone
Hydrophone
A hydrophone is a microphone designed to be used underwater for recording or listening to underwater sound. Most hydrophones are based on a piezoelectric transducer that generates electricity when subjected to a pressure change...

s of 1940s acoustic mines (which operate on the integrated volume of all frequencies) have been replaced by narrow-band sensors which are much more sensitive and selective. Mines can now be programmed to listen for highly specific acoustic signature
Acoustic signature
Acoustic signature is used to describe a combination of acoustic emissions of ships and submarines.-Contributing factors:The acoustic signature is made up of a number of individual elements...

s (e.g. a gas turbine
Gas turbine
A gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled to a downstream turbine, and a combustion chamber in-between....

 powerplant and/or cavitation
Cavitation
Cavitation is the formation and then immediate implosion of cavities in a liquidi.e. small liquid-free zones that are the consequence of forces acting upon the liquid...

 sounds from a particular design of propeller) and ignore all others. The sophistication of modern electronic
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...

 mine fuze
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...

s incorporating these Digital Signal Processing
Digital signal processing
Digital signal processing is concerned with the representation of discrete time signals by a sequence of numbers or symbols and the processing of these signals. Digital signal processing and analog signal processing are subfields of signal processing...

 capabilities makes it much more difficult to detonate the mine with electronic countermeasures
Electronic countermeasures
An electronic countermeasure is an electrical or electronic device designed to trick or deceive radar, sonar or other detection systems, like infrared or lasers. It may be used both offensively and defensively to deny targeting information to an enemy...

 because several sensors working together (e.g. magnetic, passive acoustic and water pressure) allow it to ignore signals which are not recognised as being the unique signature of an intended target vessel.

Modern influence mines such as the BAE Stonefish
Stonefish (mine)
Named after a venomous fish, the Stonefish influence mine is manufactured by a British company . Originally, the weapon was supplied to the Royal Navy, but it has also been exported to friendly countries such as Australia, which has both warstock and training versions of Stonefish.Stonefish mines...

 are computerised, with all the programmability that this implies e.g. the ability to quickly load new acoustic signature
Acoustic signature
Acoustic signature is used to describe a combination of acoustic emissions of ships and submarines.-Contributing factors:The acoustic signature is made up of a number of individual elements...

s into fuzes, or program them to detect a single, highly distinctive target signature. In this way, a mine with a passive acoustic fuze can be programmed to ignore all friendly vessels and small enemy vessels, only detonating when a very large enemy target passes over it. Alternatively, the mine can be programmed specifically to ignore all surface vessels regardless of size and exclusively target submarines.

Even as far back as the Second World War it was possible to incorporate a "ship counter" facility into mine fuzes e.g. set the mine to ignore the first two ships to pass over it (which could be mine-sweepers
Minesweeper (ship)
A minesweeper is a small naval warship designed to counter the threat posed by naval mines. Minesweepers generally detect then neutralize mines in advance of other naval operations.-History:...

 deliberately trying to trigger mines) but detonate when the third ship passes overhead—which could be a high-value target such as an aircraft carrier
Aircraft carrier
An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...

 or oil tanker
Oil tanker
An oil tanker, also known as a petroleum tanker, is a merchant ship designed for the bulk transport of oil. There are two basic types of oil tankers: the crude tanker and the product tanker. Crude tankers move large quantities of unrefined crude oil from its point of extraction to refineries...

. Even though modern mines are generally powered by a long life lithium battery
Lithium battery
Lithium batteries are disposable batteries that have lithium metal or lithium compounds as an anode. Depending on the design and chemical compounds used, lithium cells can produce voltages from 1.5 V to about 3.7 V, over twice the voltage of an ordinary zinc–carbon battery or alkaline battery...

, it is important to conserve power because they may need to remain active for months or even years. For this reason, most influence mines are designed to remain in a semi-dormant state until an unpowered (e.g. deflection of a mu-metal
Mu-metal
Mu-metal is a nickel-iron alloy that is notable for its high magnetic permeability. The high permeability makes mu-metal very effective at screening static or low-frequency magnetic fields, which cannot be attenuated by other methods. The name came from the Greek letter mu which represents...

 needle) or low-powered sensor detects the possible presence of a vessel, at which point the mine fuze
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...

 powers up fully and the passive acoustic sensors will begin to operate for some minutes. It is possible to program computerised mines to delay activation for days or weeks after being laid; similarly, they can be programmed to self-destruct
Self-destruct
A self-destruct is a mechanism which causes a device to destroy itself under a predefined set of circumstances.Self-destruct mechanisms are also found on devices and systems where malfunction could endanger large numbers of people...

 or render themselves safe after a preset period of time, e.g., 12 days or 12 months. Generally, the more sophisticated the mine design, the more likely it is to have some form of anti-handling device
Anti-handling device
An anti-handling device is an attachment to or integral part of a landmine or other munition e.g. some fuze types found in air-dropped bombs such as the M83, cluster bombs and sea mines. It is specifically designed to prevent tampering. When the protected device is disturbed it detonates, killing...

 fitted in order to hinder clearance by divers or remotely piloted submersibles.

Moored mines

The moored mine is the backbone of modern mine systems. They are deployed where water is too deep for bottom mines. They can use several kinds of instruments to detect an enemy, usually a combination of acoustic
Acoustic signature
Acoustic signature is used to describe a combination of acoustic emissions of ships and submarines.-Contributing factors:The acoustic signature is made up of a number of individual elements...

, magnetic and pressure sensor
Pressure sensor
A pressure sensor measures pressure, typically of gases or liquids. Pressure is an expression of the force required to stop a fluid from expanding, and is usually stated in terms of force per unit area. A pressure sensor usually acts as a transducer; it generates a signal as a function of the...

s, or more sophisticated optical shadows or electro potential sensors. These cost many times more than contact mines. Moored mines are effective against most kinds of ships. As they are cheaper than other anti-ship weapons they can be deployed in large numbers, making them useful area denial or "channelizing" weapons.
Moored mines usually have lifetimes of more than 10 years, and some almost unlimited. These mines usually weigh 200 kg (440 lb), including 80 kg (175 lb) of explosives (hexatonal
RDX
RDX, an initialism for Research Department Explosive, is an explosive nitroamine widely used in military and industrial applications. It was developed as an explosive which was more powerful than TNT, and it saw wide use in WWII. RDX is also known as cyclonite, hexogen , and T4...

). In excess of 150 kg (330 lb) of explosives the mine becomes inefficient, as it becomes too large to handle and the extra explosives add little to the mine's effectiveness.

Bottom mines

Bottom mines are used when the water is no more than 60 meters (180 ft) deep or when mining for submarines down to around 200 meters (660 ft). They are much harder to detect and sweep, and can carry a much larger warhead than a moored mine. Bottom mines commonly multiple types of sensors, which are less sensitive to sweeping.

These mines usually weigh between 150 and 1,500 kilograms (330 to 3,300 pounds), including between 125 and 1,400 kg (275 to 3,090 pounds) of explosives.

Unusual mines

Several specialized mines have been developed for other purposes than the common minefield.

Torpedo mine
The torpedo mine is a self-propelled variety, able to lie in wait for a target and then pursue it e.g. the CAPTOR mine
CAPTOR mine
The CAPTOR is the United States Navy's primary anti-submarine naval mine. This deep-water mine is laid by ship, aircraft or submarine, and is anchored to the ocean floor. When its sonar detects a hostile submarine, the CAPTOR launches a Mark 46 torpedo.The name CAPTOR is short for enCAPsulated...

. Other designs such as the Mk 67 Submarine Launched Mobile Mine (which is based on a Mark 37 torpedo
Mark 37 torpedo
The Mark 37 torpedo is a torpedo with electrical propulsion, developed for the US Navy after World War II. It entered service with the US Navy in the early 1950s, with over 3,300 produced. It was phased out of service with the US Navy during the 1970s, and the stockpiles were sold to foreign...

) are capable of swimming as far as 10 miles through or into a channel, harbor, shallow water area and other zones which would normally be inaccessible to craft laying the device. After reaching the target area they sink to the sea bed and act like conventionally laid influence mines. Generally, torpedo mines incorporate computerised acoustic and magnetic fuze
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...

s.

The U.S. Mark 24 "mine", code-named FIDO, was actually an ASW
Anti-submarine warfare
Anti-submarine warfare is a branch of naval warfare that uses surface warships, aircraft, or other submarines to find, track and deter, damage or destroy enemy submarines....

 homing torpedo. The mine designation was disinformation to conceal its function.

Nuclear mine
During the Cold War a test was conducted with naval mine fitted with tactical nuclear warheads Operation Crossroads
Operation Crossroads
Operation Crossroads was a series of nuclear weapon tests conducted by the United States at Bikini Atoll in mid-1946. It was the first test of a nuclear weapon after the Trinity nuclear test in July 1945...

. This weapon was experimental and never went into production.

Daisy-chained mine
This comprises two moored, floating contact mines which are tethered together by a length of steel cable or chain. Typically, each mine is situated approximately 60 feet (18.3 m) away from its neighbour, and each floats a few metres below the surface of the ocean. When the target ship hits the steel cable, the mines on either side are drawn down the side of the ship's hull, exploding on contact. In this manner it is almost impossible for target ships to pass safely between two individually moored mines. Daisy-chained mines are a very simple concept which was used during the Second World War.

Dummy mine
Plastic drums filled with sand or concrete
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

 are periodically rolled off the side of ships as real mines are laid in large mine-fields. These inexpensive false targets (designed to be of a similar shape and size as genuine mines) are intended to slow down the process of mine clearance: a mine-hunter is forced to investigate each suspicious sonar contact on the sea bed, whether it is real or not. Often a maker of Naval mines will provide both training and dummy versions of their mines.

Mine laying

Historically several methods were used to lay mines. During the First and Second World Wars, the Germans used U-boat
U-boat
U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...

s to lay mines around the UK. In the Second World War, aircraft came into favour for mine laying with the one of largest such examples being the mining of the Japanese sea routes in Operation Starvation
Operation Starvation
Operation Starvation was an American naval mining operation conducted in World War II by the Army Air Force, in which vital water routes and ports of Japan were mined by air in order to disrupt enemy shipping.-Operation:...

.

Laying a minefield is a relatively fast process with specialized ships, which is still today the most common method. These minelayer
Minelayer
Minelaying is the act of deploying explosive mines. Historically this has been carried out by ships, submarines and aircraft. Additionally, since World War I the term minelayer refers specifically to a naval ship used for deploying naval mines...

s can carry several thousand mines and manoeuvre with high precision. The mines are dropped at a predefined interval into the water behind the ship. Each mine is recorded for later clearing, but it is not unusual for these recordings to be lost together with the ships. Therefore many countries demand that all mining operations shall be planned on land and records kept so the mines can later be recovered more easily.

Other methods to lay minefields include:
  • Converted merchant ships – rolled or slid down ramps
  • Aircraft – descent to the water is slowed by a parachute
    Parachute
    A parachute is a device used to slow the motion of an object through an atmosphere by creating drag, or in the case of ram-air parachutes, aerodynamic lift. Parachutes are usually made out of light, strong cloth, originally silk, now most commonly nylon...

  • Submarines – launched from torpedo
    Torpedo
    The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

     tubes or deployed from specialized mine racks on the sides of the submarine
  • Combat boats – rolled off the side of the boat
  • Camouflaged boats – masquerading as fishing boats
  • Dropping from the shore – typically smaller, shallow-water mines
  • Attack divers – smaller shallow-water mines


In some cases, mines are automatically activated upon contact with the water. In others, a safety lanyard
Lanyard
A lanyard is a rope or cord exclusively worn around the neck or wrist to carry something. Usually it is used where there is a risk of losing the object or to ensure it is visible at all times. Aboard a ship, it may refer to a piece of rigging used to secure objects...

 is pulled (e.g. one end attached to the rail of a ship, aircraft or torpedo tube) which starts an automatic timer countdown before the arming process is complete. Typically, the automatic safety-arming process takes some minutes to complete. This is in order to give the people laying the mines sufficient time to move out of its activation/blast zone.

Germany

In the 1930s, Germany had experimented with the laying of mines by aircraft; it became a crucial element in their overall mining strategy. Aircraft had the advantage of speed, and they would never get caught in their own minefields. German mines held a large 1,000 lb. (450 kg) explosive charge. From April to June 1940, the Luftwaffe
Luftwaffe
Luftwaffe is a generic German term for an air force. It is also the official name for two of the four historic German air forces, the Wehrmacht air arm founded in 1935 and disbanded in 1946; and the current Bundeswehr air arm founded in 1956....

 laid 1,000 mines in British waters. Soviet ports were mined, as was the Arctic convoy route to Murmansk
Arctic convoys of World War II
The Arctic convoys of World War II travelled from the United Kingdom and North America to the northern ports of the Soviet Union—Arkhangelsk and Murmansk. There were 78 convoys between August 1941 and May 1945...

. The Heinkel He 115
Heinkel He 115
The Heinkel He 115 was a World War II Luftwaffe seaplane with three seats. It was used as a torpedo bomber and performed general seaplane duties, such as reconnaissance and minelaying. The plane was powered by two 720 kW BMW 132K nine-cylinder air-cooled radial engines...

 could carry two medium or one large mine while the Heinkel He 59
Heinkel He 59
|-See also:-Bibliography:* Green, William.War Planes of the Second World War: Volume Six: Floatplanes. London: Macdonald, 1962.* Green, William. Warplanes of the Third Reich. New York: Doubleday, 1972. ISBN 0-385-05782-2....

, Dornier Do 18
Dornier Do 18
The Dornier Do 18 was a development of the Do 16 flying boat. It was developed for the Luftwaffe, but Lufthansa got 5 aircraft and used these for tests between the Azores and the North American continent in 1936 and on their mail route over the South Atlantic from 1937 to 1939.27–29 March 1938 a...

, Junkers Ju 88
Junkers Ju 88
The Junkers Ju 88 was a World War II German Luftwaffe twin-engine, multi-role aircraft. Designed by Hugo Junkers' company through the services of two American aviation engineers in the mid-1930s, it suffered from a number of technical problems during the later stages of its development and early...

 and Heinkel He 111
Heinkel He 111
The Heinkel He 111 was a German aircraft designed by Siegfried and Walter Günter in the early 1930s in violation of the Treaty of Versailles. Often described as a "Wolf in sheep's clothing", it masqueraded as a transport aircraft, but its purpose was to provide the Luftwaffe with a fast medium...

 could carry more.

Soviet Union

The USSR was relatively ineffective in its use of naval mines in WWII in comparison with its record in previous wars. Small mines were developed for use in rivers and lakes, and special mines for shallow water. A very large chemical mine was designed to sink through ice with the aid of a melting compound. Special aerial mine designs finally arrived in 1943–1944, the AMD-500 and AMD-1000. Various Soviet Naval Aviation
Soviet Naval Aviation
Soviet Naval Aviation was a part of the Soviet Navy.- Origins :...

 torpedo bombers were pressed into the role of aerial mining in the Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...

 and the Black Sea
Black Sea
The Black Sea is bounded by Europe, Anatolia and the Caucasus and is ultimately connected to the Atlantic Ocean via the Mediterranean and the Aegean seas and various straits. The Bosphorus strait connects it to the Sea of Marmara, and the strait of the Dardanelles connects that sea to the Aegean...

, including Ilyushin DB-3
Ilyushin DB-3
The Ilyushin DB-3 was a Soviet bomber aircraft of World War II. It was a twin-engined, low-wing monoplane that first flew in 1935. It was the precursor of the Ilyushin Il-4...

s, Il-4
Ilyushin Il-4
|-See also:-Bibliography:* Gordon, Yefim and Khazanov, Dmitri. Soviet Combat Aircraft of the Second World War, Volume 2: Twin-Engined Fighters, Attack Aircraft and Bombers. Earl Shilton, UK: Midland Publishing Ltd., 2006. ISBN 1-85780-084-2...

s and Lend Lease Douglas Boston IIIs.

United Kingdom

In September 1939, the UK announced the placement of extensive defensive minefields in waters surrounding the Home Islands. Offensive aerial mining operations began in April 1940 when 38 mines were laid at each of these locations: the Elbe River, the port of Lübeck
Lübeck
The Hanseatic City of Lübeck is the second-largest city in Schleswig-Holstein, in northern Germany, and one of the major ports of Germany. It was for several centuries the "capital" of the Hanseatic League and, because of its Brick Gothic architectural heritage, is listed by UNESCO as a World...

 and the German naval base at Kiel
Kiel
Kiel is the capital and most populous city in the northern German state of Schleswig-Holstein, with a population of 238,049 .Kiel is approximately north of Hamburg. Due to its geographic location in the north of Germany, the southeast of the Jutland peninsula, and the southwestern shore of the...

. In the next 20 months, mines delivered by aircraft sank or damaged 164 Axis ships with the loss of 94 aircraft. By comparison, direct aerial attacks on Axis shipping had sunk or damaged 105 vessels at a cost of 373 aircraft lost. The advantage of aerial mining became clear, and the United Kingdom geared up for it. A total of 48,000 aerial mines were laid by the Royal Air Force
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

 (RAF) in the European Theatre
European Theatre of World War II
The European Theatre of World War II was a huge area of heavy fighting across Europe from Germany's invasion of Poland on September 1, 1939 until the end of the war with the German unconditional surrender on May 8, 1945...

 during World War II.

United States

The United States's early aerial mining efforts used smaller aircraft unable to carry many mines. Using TBF Avenger
TBF Avenger
The Grumman TBF Avenger was a torpedo bomber developed initially for the United States Navy and Marine Corps, and eventually used by several air or naval arms around the world....

 torpedo bombers, the US Navy mounted a direct aerial mining attack on enemy shipping in Palau
Palau
Palau , officially the Republic of Palau , is an island nation in the Pacific Ocean, east of the Philippines and south of Tokyo. In 1978, after three decades as being part of the United Nations trusteeship, Palau chose independence instead of becoming part of the Federated States of Micronesia, a...

 on 30 March 1944 in concert with simultaneous conventional bombing and strafing attacks. The dropping of 78 mines stopped 32 Japanese ships from escaping Koror
Koror
Koror is the state comprising the main commercial centre of the Republic of Palau. It consists of several islands, the most prominent being Koror Island ....

 harbor; the combined operation sank or damaged 36 ships. Two Avengers were lost; their crews were recovered. The mines brought port usage to a halt for 20 days; further mine-laying in the area contributed to the Japanese abandoning Palau as a base.

As early as 1942, American mining experts such as Naval Ordnance Laboratory scientist Dr. Ellis A. Johnson, Commander, Naval Reserve, suggested massive aerial mining operations against Japan's "outer zone" (Korea and northern China) as well as the "inner zone", their home islands
Japanese Archipelago
The , which forms the country of Japan, extends roughly from northeast to southwest along the northeastern coast of the Eurasia mainland, washing upon the northwestern shores of the Pacific Ocean...

. First, aerial mines would have to be developed further and manufactured in large numbers. Second, laying the mines would require a sizable air group. The US Army Air Force had the carrying capacity but considered mining to be the Navy's job. The US Navy lacked suitable aircraft. Johnson set about convincing General Curtis LeMay
Curtis LeMay
Curtis Emerson LeMay was a general in the United States Air Force and the vice presidential running mate of American Independent Party candidate George Wallace in 1968....

 of the efficacy of very heavy bombers laying aerial mines.

In the meantime, B-24 Liberator
B-24 Liberator
The Consolidated B-24 Liberator was an American heavy bomber, designed by Consolidated Aircraft of San Diego, California. It was known within the company as the Model 32, and a small number of early models were sold under the name LB-30, for Land Bomber...

, PBY Catalina
PBY Catalina
The Consolidated PBY Catalina was an American flying boat of the 1930s and 1940s produced by Consolidated Aircraft. It was one of the most widely used multi-role aircraft of World War II. PBYs served with every branch of the United States Armed Forces and in the air forces and navies of many other...

 and other available bomber aircraft took part in localized mining operations in the Southwest Pacific
South West Pacific theatre of World War II
The South West Pacific Theatre, technically the South West Pacific Area, between 1942 and 1945, was one of two designated area commands and war theatres enumerated by the Combined Chiefs of Staff of World War II in the Pacific region....

 and the China Burma India (CBI)
China Burma India Theater of World War II
China Burma India Theater was the name used by the United States Army for its forces operating in conjunction with British and Chinese Allied air and land forces in China, Burma, and India during World War II...

 Theaters, beginning with a very successful attack on the Yangon River
Yangon River
The Yangon River is formed by the confluence of the Pegu and Myitmaka rivers and is a marine estuary that runs from Yangon emptying into the Gulf of Martaban of the Andaman Sea...

 in February 1943. Aerial minelaying operations involved a coalition of British, Australian and American aircrews, with the RAF and the Royal Australian Air Force
Royal Australian Air Force
The Royal Australian Air Force is the air force branch of the Australian Defence Force. The RAAF was formed in March 1921. It continues the traditions of the Australian Flying Corps , which was formed on 22 October 1912. The RAAF has taken part in many of the 20th century's major conflicts...

 (RAAF) carrying out 60% of the sorties and the USAAF and US Navy covering 40%. Both British and American mines were used. Japanese merchant shipping suffered tremendous losses, while Japanese mine sweeping forces were spread too thin attending to far-flung ports and extensive coastlines. Admiral Thomas C. Kinkaid
Thomas C. Kinkaid
Thomas Cassin Kinkaid was an admiral in the United States Navy during World War II. He built a reputation as a "fighting admiral" in the aircraft carrier battles of 1942 and commanded the Allied forces in the Aleutian Islands Campaign...

, who directed nearly all RAAF mining operations in CBI, heartily endorsed aerial mining, writing in July 1944 that "aerial mining operations were of the order of 100 times as destructive to the enemy as an equal number of bombing missions against land targets."

Finally, in March 1945, Operation Starvation
Operation Starvation
Operation Starvation was an American naval mining operation conducted in World War II by the Army Air Force, in which vital water routes and ports of Japan were mined by air in order to disrupt enemy shipping.-Operation:...

 began in earnest, using 160 of LeMay's B-29 Superfortress
B-29 Superfortress
The B-29 Superfortress is a four-engine propeller-driven heavy bomber designed by Boeing that was flown primarily by the United States Air Forces in late-World War II and through the Korean War. The B-29 was one of the largest aircraft to see service during World War II...

 bombers to attack Japan's inner zone. Almost half of the mines were the US-built Mark 25 model, carrying 1250 lbs of explosives and weighing about 2,000 lbs. Other mines used included the smaller 1,000 lb Mark 26. 15 B-29s were lost while 293 enemy merchant ships were sunk or damaged. 12,000 aerial mines were laid, a significant barrier to Japan's access to outside resources. Prince Fumimaro Konoe
Fumimaro Konoe
Prince was a politician in the Empire of Japan who served as the 34th, 38th and 39th Prime Minister of Japan and founder/leader of the Taisei Yokusankai.- Early life :...

 said after the war that the aerial mining by B-29s had been "equally as effective as the B-29 attacks on Japanese industry at the closing stages of the war when all food supplies and critical material were prevented from reaching the Japanese home islands." The United States Strategic Bombing Survey (Pacific War)
Strategic bombing survey (Pacific War)
The "Strategic bombing survey " was a United States Army Air Forces report on the impact of strategic bombing in World War II in the Pacific Campaign.A separate report was made for the atomic attacks.- External links :* *...

 concluded that it would have been more efficient to combine the United States's effective anti-shipping submarine effort with land- and carrier-based air power to strike harder against merchant shipping and begin a more extensive aerial mining campaign earlier in the war. Survey analysts projected that this would have starved Japan, forcing an earlier end to the war. After the war, Dr. Johnson looked at the Japan inner zone shipping results, comparing the total economic cost of submarine-delivered mines versus air-dropped mines and found that, though 1 in 12 submarine mines connected with the enemy as opposed to 1 in 21 for aircraft mines, the aerial mining operation was about ten times less expensive per enemy ton sunk.

Clearing WWII aerial mines

Between 600,000 and 1,000,000 naval mines of all types were laid in World War II. Advancing military forces worked to clear mines from newly taken areas, but extensive minefields remained in place after the war. Air-dropped mines had an additional problem for mine sweeping operations: they were not meticulously charted. In Japan, much of the B-29 mine-laying work had been performed at high altitude, with the drifting on the wind of mines carried by parachute adding a randomizing factor to their placement. Generalized danger areas were identified, with only the quantity of mines given in detail. Mines used in Operation Starvation
Operation Starvation
Operation Starvation was an American naval mining operation conducted in World War II by the Army Air Force, in which vital water routes and ports of Japan were mined by air in order to disrupt enemy shipping.-Operation:...

 were supposed to be self-sterilizing, but the circuit did not always work. Clearing the mines took so many years that the task was eventually given to the Japan Maritime Self-Defense Force
Japan Maritime Self-Defense Force
The , or JMSDF, is the naval branch of the Japan Self-Defense Forces, tasked with the naval defense of Japan. It was formed following the dissolution of the Imperial Japanese Navy after World War II....

.

For the purpose of clearing all types of naval mines, the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 employed German crews and minesweepers
Minesweeper (ship)
A minesweeper is a small naval warship designed to counter the threat posed by naval mines. Minesweepers generally detect then neutralize mines in advance of other naval operations.-History:...

 from June 1945 to January 1948, organised in the German Mine Sweeping Administration
German Mine Sweeping Administration
The German Mine Sweeping Administration was formed from former crews and vessels of the Nazi German Kriegsmarine for the purpose of mine sweeping after the Second World War, predominantly in the North Sea and Baltic Sea, and existed from June 1945 to January 1948.-History:The GMSA was formed on 21...

, the GMSA, which consisted of 27,000 members of the former Kriegsmarine
Kriegsmarine
The Kriegsmarine was the name of the German Navy during the Nazi regime . It superseded the Kaiserliche Marine of World War I and the post-war Reichsmarine. The Kriegsmarine was one of three official branches of the Wehrmacht, the unified armed forces of Nazi Germany.The Kriegsmarine grew rapidly...

and 300 vessels. Mine clearing wasn't always successful: a number of ships were damaged or sunk by mines after the war. Two such examples were the Liberty ship
Liberty ship
Liberty ships were cargo ships built in the United States during World War II. Though British in conception, they were adapted by the U.S. as they were cheap and quick to build, and came to symbolize U.S. wartime industrial output. Based on vessels ordered by Britain to replace ships torpedoed by...

s Pierre Gibault which was scrapped after hitting a mine in a previously cleared area off the Greek island of Kythira
Kythira
Cythera is an island in Greece, once part of the Ionian Islands. It lies opposite the south-eastern tip of the Peloponnese peninsula. It is administratively part of the Islands regional unit, which is part of the Attica region , Greece.For many centuries, while naval travel was the only means...

 in June 1945, and Nathaniel Bacon which hit a minefield off Civitavecchia
Civitavecchia
Civitavecchia is a town and comune of the province of Rome in the central Italian region of Lazio. A sea port on the Tyrrhenian Sea, it is located 80 kilometers west-north-west of Rome, across the Mignone river. The harbor is formed by two piers and a breakwater, on which is a lighthouse...

, Italy in December 1945, caught fire, was beached, and broke in two.

Damage

The damage that may be caused by a mine depends on the "shock factor value", a combination of the initial strength of the explosion and of the distance between the target and the detonation. When taken in reference to ship hull plating, the term "Hull Shock Factor" (HSF) is used, while keel damage is termed "Keel Shock Factor" (KSF). If the explosion is directly underneath the keel, then HSF is equal to KSF, but explosions that are not directly underneath the ship will have a lower value of KSF.

Direct damage

Usually only created by contact mines, direct damage is a hole blown in the ship. Among the crew, shrapnel wounds are the most common form of damage. Flooding typically occurs in one or two main watertight compartments which can sink smaller ships or disable larger ones. Contact mine damage often occurs at or close to the waterline near the bow, but depending on circumstances a ship could be hit anywhere on its outer hull surface (the USS Samuel B Roberts mine attack being a good example of a contact mine detonating amidships and underneath the ship).

Bubble jet effect

The bubble jet effect occurs when a mine detonates in the water a short distance away from the ship. The explosion creates a bubble in the water, and due to the difference in pressure, the bubble will collapse from the bottom. The bubble is buoyant and so it rises towards the surface. If the bubble reaches the surface as it collapses it can create a pillar of water that can go over a hundred meters into the air (a "columnar plume"). If conditions are right and the bubble collapses onto the ship's hull the damage to the ship can be extremely serious; the collapsing bubble forms a high energy jet that can break a meter wide hole straight through the ship, flooding one or more compartments, and is capable of breaking smaller ships apart. The crew in the areas hit by the pillar are usually killed instantly. Other damage is usually limited.

The Baengnyeong incident, in which the ROKS Cheonan
ROKS Cheonan (PCC-772)
ROKS Cheonan was a South Korean Pohang-class corvette of the Republic of Korea Navy , commissioned in 1989. On 26 March 2010, it broke in two and sank near the sea border with North Korea...

 broke in half and sank off the coast South Korea
South Korea
The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...

 in 2010, is thought by some to have been caused by the bubble jet effect.

Shock effect

If the mine detonates at a distance from the ship, the change in water pressure causes the ship to resonate. This is frequently the most deadly type of explosion, if it is strong enough. The whole ship is dangerously shaken and everything onboard is tossed around. Engines rip from their beds, cables from their holders, etc. A badly shaken ship usually sinks quickly, with hundreds, or even thousands of small leaks all over the ship and no way to power the pumps. The crew fare no better, as the violent shaking tosses them around. This shaking is powerful enough to cause disabling injury to knees and other joints in the body, particularly if the affected person stands on surfaces connected directly to the hull (such as steel decks).

The resulting gas cavitation and shock-front-differential over the width of the human body is sufficient to stun or kill divers
Frogman
A frogman is someone who is trained to scuba diving or swim underwater in a military capacity which can include combat. Such personnel are also known by the more formal names of combat diver or combatant diver or combat swimmer....

.

Countermeasures

Weapons are frequently a few steps ahead of countermeasures, and mines are no exception. In this field the British, with their large seagoing navy, have had the bulk of world experience, and most anti-mine developments, such as de-gaussing and the double-L sweep were British inventions. When on operational missions, such as the recent invasion of Iraq, the US still rely on British and Canadian minesweeping services. The US has worked on some innovative mine hunting countermeasures, such as the use of military dolphin
Military dolphin
A military dolphin is a dolphin trained for military uses. The United States and Russian militaries have trained and employed oceanic dolphins for several reasons. Such military dolphins have been trained to rescue lost naval swimmers or to locate underwater mines.The U.S. Navy trains dolphins and...

s to detect and flag mines. However, they are of questionable effectiveness.

Passive countermeasures

Ships can be designed to be difficult for mines to detect, to avoid detonating them. This is especially true for minesweepers and mine hunters that work in minefields, where a minimal signature outweighs the need for armour and speed. These ships have hulls of glass fibre or wood instead of steel to avoid magnetic signatures, they use special propulsion systems, such as Voith-Schneider
Voith-Schneider
The Voith Schneider propeller , also known as a cycloidal drive is a specialized marine propulsion system . It is highly maneuverable, being able to change the direction of its thrust almost instantaneously...

 propellers, to limit the acoustic signature
Acoustic signature
Acoustic signature is used to describe a combination of acoustic emissions of ships and submarines.-Contributing factors:The acoustic signature is made up of a number of individual elements...

. They are built with hulls that produce a minimal pressure signature. These measures create other problems. They are expensive, slow, and vulnerable to enemy fire. Therefore, they need protection. Many modern ships have a mine-warning sonar
Sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

—a simple sonar looking forward and warning the crew if it detects possible mines ahead. It is only effective when the ship is moving slowly.
(See Also SQQ-32 Mine-hunting sonar
SQQ-32 Mine-hunting sonar
The AN/SQQ-32 is a mine-hunting sonar system. Developed by Raytheon for the United States Navy, it includes an active sonar for detecting objects on the surface, in the volume, and on the bottom of the ocean, and another sonar for classifying those objects as mines or non-mines. The classification...

)


A steel-hulled ship can be degaussed
Degaussing
Degaussing is the process of decreasing or eliminating an unwanted magnetic field. It is named after Carl Friedrich Gauss, an early researcher in the field of magnetism...

(more correctly, de-oerstedted or depermed
Deperming
Deperming, or degaussing, is a procedure for erasing the permanent magnetism from ships and submarines to camouflage them against magnetic detection vessels and enemy marine mines....

) using a special degaussing station that contains many large coils and induces a magnetic field in the hull with alternating current to demagnetize the hull. This is a rather problematic solution, as magnetic compasses need recalibration and all metal objects must be kept in exactly the same place. Ships slowly regain their magnetic field as they travel through the Earth's magnetic field, so the process has to be repeated every six months.

A simpler variation of this technique, called wiping, was developed by Charles F. Goodeve
Charles F. Goodeve
Sir Charles Frederick Goodeve, OBE, FRS, was a Canadian chemist and pioneer in operations research for the British. During World War II, he was instrumental in developing the "hedgehog" antisubmarine warfare weapon and the degaussing method for protecting ships from naval mines.- Biography...

 which saved time and resources.

Between 1941 and 1943 the US Naval Gun factory (a division of the Naval Ordinance Laboratory) in Washington D.C. built physical models of all US Naval ships. Three kinds of steel were used in shipbuilding: mild steel for bulkheads, a mixture of mild steel and high tensile steel for the hull, and special treatment steel for armor plate. The models were placed within coils which could simulate the Earth's magnetic field at any location. The magnetic signatures were measured with degaussing coils. The objective was to reduce the vertical component of the combination of the Earth's field and the ship's field at the usual depth of German mines. From the measurements, coils were placed and coil currents determined to minimize the chance of detonation for any ship at any heading at any latitude.

Some ships are built with magnetic inductor
Inductor
An inductor is a passive two-terminal electrical component used to store energy in a magnetic field. An inductor's ability to store magnetic energy is measured by its inductance, in units of henries...

s, large coils placed along the ship to counter the ship's magnetic field. Using magnetic probes in strategic parts of the ship, the strength of the current in the coils can be adjusted to minimize the total magnetic field. This is a heavy and clumsy solution, suited only to small-to-medium sized ships. Boats typically lack the generators and space for the solution, while the amount of power needed to overcome the magnetic field of a large ship is impractical.

Active countermeasures

Active countermeasures are ways to clear a path through a minefield or remove it completely. This is one of the most important tasks of any mine warfare flotilla.

Mine sweeping

A sweep is either a contact sweep, a wire dragged through the water by one or two ships to cut the mooring wire of floating mines, or a distance sweep that mimics a ship to detonate the mines. The sweeps are dragged by minesweeper
Minesweeper (ship)
A minesweeper is a small naval warship designed to counter the threat posed by naval mines. Minesweepers generally detect then neutralize mines in advance of other naval operations.-History:...

s, either purpose-built military ships or converted trawlers. Each run covers between one and two hundred meters, and the ships must move slowly in a straight line, making them vulnerable to enemy fire. This was exploited by the Turkish army in the Battle of Gallipoli
Battle of Gallipoli
The Gallipoli Campaign, also known as the Dardanelles Campaign or the Battle of Gallipoli, took place at the peninsula of Gallipoli in the Ottoman Empire between 25 April 1915 and 9 January 1916, during the First World War...

 in 1915, when mobile howitzer
Howitzer
A howitzer is a type of artillery piece characterized by a relatively short barrel and the use of comparatively small propellant charges to propel projectiles at relatively high trajectories, with a steep angle of descent...

 batteries prevented the British and French from clearing a way through minefields.

If a contact sweep hits a mine, the wire of the sweep rubs against the mooring wire until it is cut. Sometimes "cutters", explosive devices to cut the mine's wire, are used to lessen the strain on the sweeping wire. Mines cut free are recorded and collected for research or shot with a deck gun.

Minesweepers protect themselves with an oropesa
Oropesa
An Oropesa is a streamlined towed body used in the process of minesweeping. The role of the Oropesa is to keep the towed sweep at a determined depth and position from the sweeping ship....

 or paravane
Paravane (weapon)
The paravane is a form of towed underwater "glider". It was developed by Cdr Usborne and Lt Burney financed by Sir George White, founder of the Bristol Aeroplane Company....

 instead of a second minesweeper. These are torpedo-shaped towed bodies, similar in shape to a Harvey Torpedo, that are streamed from the sweeping vessel thus keeping the sweep at a determined depth and position. Some large warships were routinely equipped with paravane sweeps near the bows in case they inadvertently sailed into minefields—the mine would be deflected towards the paravane by the wire instead of towards the ship by its wake. More recently, heavy-lift helicopters have dragged minesweeping sleds, as in the 1991 Persian Gulf War.

The distance sweep mimics the sound and magnetism of a ship and is pulled behind the sweeper. It has floating coils and large underwater drums. It is the only sweep effective against bottom mines.

During the Second World War, RAF Coastal Command
RAF Coastal Command
RAF Coastal Command was a formation within the Royal Air Force . Founded in 1936, it was the RAF's premier maritime arm, after the Royal Navy's secondment of the Fleet Air Arm in 1937. Naval aviation was neglected in the inter-war period, 1919–1939, and as a consequence the service did not receive...

 used Vickers Wellington
Vickers Wellington
The Vickers Wellington was a British twin-engine, long range medium bomber designed in the mid-1930s at Brooklands in Weybridge, Surrey, by Vickers-Armstrongs' Chief Designer, R. K. Pierson. It was widely used as a night bomber in the early years of the Second World War, before being displaced as a...

 bombers Wellington DW.Mk I fitted with degaussing coils to trigger magnetic mines.

Modern influence mines are designed to discriminate against false inputs and are therefore much harder to sweep. They often contain inherent anti-sweeping mechanisms. For example, they may be programmed to respond to the unique noise of a particular ship-type, its associated magnetic signature and the typical pressure displacement of such a vessel. As a result, a mine-sweeper must accurately guess and mimic the required target signature in order to trigger detonation. The task is complicated by the fact that an influence mine may have one or more of a hundred different potential target signatures programmed into it.

Another anti-sweeping mechanism is a ship-counter in the mine fuze. When enabled, this allows detonation only after the mine fuze
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...

 has been triggered a pre-set number of times. To further complicate matters, influence mines may be programmed to arm themselves (or disarm automatically—known as self-sterilization) after a pre-set time. During the pre-set arming delay (which could last days or even weeks) the mine would remain dormant and ignore any target stimulus, whether genuine or faked.

When influence mines are laid in an ocean minefield, they may have various combinations of fuze settings configured. For example, some mines (with the acoustic sensor enabled) may become active within three hours of being laid, others (with the acoustic and magnetic sensors enabled) may become active after two weeks but have the ship-counter mechanism set to ignore the first two trigger events, and still others in the same minefield (with the magnetic and pressure sensors enabled) may not become armed until three weeks have passed. Groups of mines within this mine-field may have different target signatures which may or may not overlap. The fuzes on influence mines allow many different permutations, which complicates the clearance process.

Mines with ship-counters, arming delays and highly specific target signatures in mine fuzes can falsely convince a belligerent that a particular area is clear of mines or has been swept effectively because a succession of vessels have already passed through safely.

Mine hunting

Mine hunting is very different from sweeping, although some minehunter
Minehunter
Minehunters are mine countermeasure vessels that actively detect and destroy individual naval mines. Minesweepers, on the other hand, clear mined areas as a whole, without prior detection of mines...

s can do both tasks. Mines are hunted using sonar, then inspected and destroyed either by divers or ROV
Remotely operated vehicle
A remotely operated vehicle is a tethered underwater vehicle. They are common in deepwater industries such as offshore hydrocarbon extraction. An ROV may sometimes be called a remotely operated underwater vehicle to distinguish it from remote control vehicles operating on land or in the air. ROVs...

s (remote controlled unmanned mini submarines). It is slow, but also the most reliable way to remove mines. Mine hunting started during the Second World War, but it was only after the war that it became truly effective.

Sea mammals (mainly the Bottlenose Dolphin
Bottlenose Dolphin
Bottlenose dolphins, the genus Tursiops, are the most common and well-known members of the family Delphinidae, the family of oceanic dolphins. Recent molecular studies show the genus contains two species, the common bottlenose dolphin and the Indo-Pacific bottlenose dolphin , instead of one...

) have been trained to hunt and mark mines, most famously by the U.S. Navy Marine Mammal Program
U.S. Navy Marine Mammal Program
The U.S. Navy Marine Mammal Program is a program administered by the U.S. Navy which studies the military use of marine mammals—principally Bottlenose Dolphins and California Sea Lions—and trains animals to perform tasks such as ship and harbor protection, mine detection and clearance, and...

. Mine-clearance dolphins were deployed in the Persian Gulf
Persian Gulf
The Persian Gulf, in Southwest Asia, is an extension of the Indian Ocean located between Iran and the Arabian Peninsula.The Persian Gulf was the focus of the 1980–1988 Iran-Iraq War, in which each side attacked the other's oil tankers...

 during the Iraq War in 2003. The Navy claims that these dolphins were effective in helping to clear more than 100 antiship mines and underwater booby trap
Booby trap
A booby trap is a device designed to harm or surprise a person, unknowingly triggered by the presence or actions of the victim. As the word trap implies, they often have some form of bait designed to lure the victim towards it. However, in other cases the device is placed on busy roads or is...

s from Umm Qasr Port
Umm Qasr Port
Umm Qasr Port is Iraq's only deep water port, part of the city of Umm Qasr.Iraq's second port in scale of size and goods shipped to the port of Basra, it is strategically important, located on the western edge of the al-Faw peninsula, where the mouth of the Shatt al Arab waterway enters the Persian...

.

French naval officer Jacques Yves Cousteau's Undersea Research Group was once involved in mine-hunting operations: They removed or detonated a variety of German mines, but one particularly defusion-resistant batch—equipped with acutely sensitive pressure, magnetic, and acoustic sensors and wired together so that one explosion would trigger the rest—was simply left undisturbed for years until corrosion would (hopefully) disable the mines.

Mine breaking

A more drastic method is simply to load a cargo ship with cargo that makes her less vulnerable to sinking (wood for example) and drive her through the minefield, letting the ship to be protected follow the same path. This method was employed by the German Kriegsmarine during WWII, using converted ships known as Sperrbrecher
Sperrbrecher
A Sperrbrecher , was a German auxiliary ship of the Second World War that was intended to serve as a type of minesweeper, by sailing ahead of other vessels through minefields, intending to detonate any mines in their path...

("barrage breaker"). Alternatively, a shallow draught vessel can be steamed through the minefield at high speed to generate a pressure wave sufficient to trigger mines, with the minesweeper moving fast enough to be sufficiently clear of the pressure wave so that triggered mines do not destroy the ship itself. These techniques are the only way to sweep pressure mines. The technique can be simply countered by use of a ship-counter, set to allow a certain number of passes before the mine is actually triggered. Modern doctrine calls for ground mines to be hunted rather than swept. A new system is being introduced for sweeping pressure mines however counters are going to remain a problem.

An updated form of mine breaking is the use of small unmanned ROV
Remotely operated vehicle
A remotely operated vehicle is a tethered underwater vehicle. They are common in deepwater industries such as offshore hydrocarbon extraction. An ROV may sometimes be called a remotely operated underwater vehicle to distinguish it from remote control vehicles operating on land or in the air. ROVs...

s that simulate the acoustic and magnetic signatures of larger ships and are built to survive exploding mines. Repeated sweeps would be required in case one or more of the mines had its "ship counter" facility enabled i.e. were programmed to ignore the first 2, 3, or even 6 target activations.

US Mines

The United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 MK56 ASW mine (the oldest still in use by the US
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

) was developed in 1966. More advanced mines include the MK60 CAPTOR
CAPTOR mine
The CAPTOR is the United States Navy's primary anti-submarine naval mine. This deep-water mine is laid by ship, aircraft or submarine, and is anchored to the ocean floor. When its sonar detects a hostile submarine, the CAPTOR launches a Mark 46 torpedo.The name CAPTOR is short for enCAPsulated...

 (short for "encapsulated torpedo"), the MK62 and MK63 Quickstrike and the MK67 SLMM (Submarine Launched Mobile Mine). Today, most U.S. naval mines are delivered by aircraft.

MK67 SLMM Submarine Launched Mobile Mine

The SLMM was developed by the United States as a submarine deployed mine for use in areas inaccessible for other mine deployment techniques or for covert mining of hostile environments. The SLMM is a shallow-water mine and is basically a modified Mark 37 torpedo
Mark 37 torpedo
The Mark 37 torpedo is a torpedo with electrical propulsion, developed for the US Navy after World War II. It entered service with the US Navy in the early 1950s, with over 3,300 produced. It was phased out of service with the US Navy during the 1970s, and the stockpiles were sold to foreign...

.

General characteristics
  • Type: Submarine-laid bottom mine
  • Detection System: Magnetic/seismic/pressure target detection devices (TDDs)
  • Dimensions: 485 mm by 4.09 m (19 by 161 in)
  • Depth Range: Shallow water
  • Weight: 754 kg (1658 lb)
  • Explosives: 230 kg (510 lb) high explosive
  • Date Deployed: 1987

MK65 Quickstrike

The Quickstrike is a family of shallow-water aircraft-laid mines used by the United States, primarily against surface craft. The MK65 is a 2,000-lb (900 kg) dedicated, purpose-built mine. However, other Quickstrike versions (MK62, MK63, and MK64) are converted general-purpose bombs. These latter three mines are actually a single type of electronic fuze
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...

 fitted to Mk82, Mk83 and Mk84 air-dropped bombs. Because this latter type of Quickstrike fuze only takes up a small amount of storage space compared to a dedicated sea mine, the air-dropped bomb casings have dual purpose i.e. can be fitted with conventional contact fuzes and dropped on land targets, or have a Quickstrike fuze fitted which converts them into sea mines.

General characteristics
  • Type: aircraft-laid bottom mine (with descent to water slowed by a parachute or other mechanism)
  • Detection System: Magnetic/seismic/pressure target detection devices (TDDs)
  • Dimensions: 740 mm by 3.25 m (29 by 128 in)
  • Depth Range: Shallow water
  • Weight: 1086 kg (2390 lb)
  • Explosives: Various loads
  • Date Deployed: 1983


MK56

General characteristics
  • Type: Aircraft laid moored mine
  • Detection System: Total field magnetic exploder
  • Dimensions: 570 mm by 2.9 m (22.4 by 114.3 in)
  • Depth Range: Moderate depths
  • Weight: 909 kg (2000 lb)
  • Explosives: 164 kg (360 lb) HBX-3
  • Date Deployed: 1966

Royal Navy

According to a statement made to the UK Parliament in 2002:
"...the Royal Navy does not have any mine stocks and has not had since 1992. Notwithstanding this, the United Kingdom retains the capability to lay mines and continues research into mine exploitation. Practice mines, used for exercises, continue to be laid in order to retain the necessary skills".


However, a British company (BAE Systems
BAE Systems
BAE Systems plc is a British multinational defence, security and aerospace company headquartered in London, United Kingdom, that has global interests, particularly in North America through its subsidiary BAE Systems Inc. BAE is among the world's largest military contractors; in 2009 it was the...

) does manufacture the Stonefish
Stonefish (mine)
Named after a venomous fish, the Stonefish influence mine is manufactured by a British company . Originally, the weapon was supplied to the Royal Navy, but it has also been exported to friendly countries such as Australia, which has both warstock and training versions of Stonefish.Stonefish mines...

 influence mine for export to friendly countries such as Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, which has both war stock and training versions of Stonefish, in addition to stocks of smaller Italian
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

 MN103 Manta mines. The computerised fuze
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...

 on a Stonefish mine contains acoustic, magnetic and water pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

 displacement target detection sensors. Stonefish can be deployed by fixed-wing aircraft, helicopters, surface vessels and submarines. An optional kit is available to allow Stonefish to be air-dropped, comprising an aerodynamic tail-fin section and parachute
Parachute
A parachute is a device used to slow the motion of an object through an atmosphere by creating drag, or in the case of ram-air parachutes, aerodynamic lift. Parachutes are usually made out of light, strong cloth, originally silk, now most commonly nylon...

 pack to retard the weapon's descent. The operating depth of Stonefish ranges between 30 and 200 metres. The mine weighs 990 kilograms and contains a 600 kilogram aluminised
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 PBX explosive warhead
Warhead
The term warhead refers to the explosive material and detonator that is delivered by a missile, rocket, or torpedo.- Etymology :During the early development of naval torpedoes, they could be equipped with an inert payload that was intended for use during training, test firing and exercises. This...

.

See also

  • Stonefish influence mine
    Stonefish (mine)
    Named after a venomous fish, the Stonefish influence mine is manufactured by a British company . Originally, the weapon was supplied to the Royal Navy, but it has also been exported to friendly countries such as Australia, which has both warstock and training versions of Stonefish.Stonefish mines...

  • Royal Navy's Admiralty Mining Establishment
    Admiralty Mining Establishment
    The Admiralty Mining Establishment was a technical department of the Royal Navyresponsible for both the design of naval mines and the development of suitable countermeasures. In keeping with many technical departments it employed both military and highly skilled, civilian personnel...

  • Land mine
    Land mine
    A land mine is usually a weight-triggered explosive device which is intended to damage a target—either human or inanimate—by means of a blast and/or fragment impact....

  • HMHS Britannic
    HMHS Britannic
    HMHS Britannic was the third and largest of the White Star Line. She was the sister ship of and , and was intended to enter service as a transatlantic passenger liner. She was launched just before the start of the First World War and was laid up at her builders in Belfast for many months before...

  • The Corfu Channel Case (United Kingdom of Great Britain and Northern Ireland v. People's Republic of Albania)

External links

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