Lifeboat (shipboard)
Overview
 
A lifeboat is a small, rigid or inflatable watercraft
Watercraft
A watercraft is a vessel or craft designed to move across or through water. The name is derived from the term "craft" which was used to describe all types of water going vessels...

 carried for emergency evacuation in the event of a disaster aboard ship. In the military, a lifeboat may be referred to as a whaleboat
Whaleboat
A whaleboat is a type of open boat that is relatively narrow and pointed at both ends, enabling it to move either forwards or backwards equally well. It was originally developed for whaling, and later became popular for work along beaches, since it does not need to be turned around for beaching or...

, dinghy
Dinghy
A dinghy is a type of small boat, often carried or towed for use as a ship's boat by a larger vessel. It is a loanword from either Bengali or Urdu. The term can also refer to small racing yachts or recreational open sailing boats. Utility dinghies are usually rowboats or have an outboard motor,...

, or gig
Captain's Gig
The captain's gig is a boat used on naval ships as the captain's private taxi. It is a catchall phrase for this type of craft and over the years it has gradually increased in size, changed with the advent of new technologies for locomotion, and been crafted from increasingly more durable...

. The ship's tender
Ship's tender
A ship's tender, usually referred to as a tender, is a boat, or a larger ship used to service a ship, generally by transporting people and/or supplies to and from shore or another ship...

s of cruise ship
Cruise ship
A cruise ship or cruise liner is a passenger ship used for pleasure voyages, where the voyage itself and the ship's amenities are part of the experience, as well as the different destinations along the way...

s often double as lifeboats. Recreational sailors sometimes carry small proactive lifeboats instead of inflatable life rafts. These boats are unsinkable, and can be sailed to safety. Lifeboat drills are required by law on larger commercial ships.

Inflatable lifeboats may be equipped with auto-inflation (carbon dioxide or nitrogen) canisters or mechanical pumps.
Encyclopedia
A lifeboat is a small, rigid or inflatable watercraft
Watercraft
A watercraft is a vessel or craft designed to move across or through water. The name is derived from the term "craft" which was used to describe all types of water going vessels...

 carried for emergency evacuation in the event of a disaster aboard ship. In the military, a lifeboat may be referred to as a whaleboat
Whaleboat
A whaleboat is a type of open boat that is relatively narrow and pointed at both ends, enabling it to move either forwards or backwards equally well. It was originally developed for whaling, and later became popular for work along beaches, since it does not need to be turned around for beaching or...

, dinghy
Dinghy
A dinghy is a type of small boat, often carried or towed for use as a ship's boat by a larger vessel. It is a loanword from either Bengali or Urdu. The term can also refer to small racing yachts or recreational open sailing boats. Utility dinghies are usually rowboats or have an outboard motor,...

, or gig
Captain's Gig
The captain's gig is a boat used on naval ships as the captain's private taxi. It is a catchall phrase for this type of craft and over the years it has gradually increased in size, changed with the advent of new technologies for locomotion, and been crafted from increasingly more durable...

. The ship's tender
Ship's tender
A ship's tender, usually referred to as a tender, is a boat, or a larger ship used to service a ship, generally by transporting people and/or supplies to and from shore or another ship...

s of cruise ship
Cruise ship
A cruise ship or cruise liner is a passenger ship used for pleasure voyages, where the voyage itself and the ship's amenities are part of the experience, as well as the different destinations along the way...

s often double as lifeboats. Recreational sailors sometimes carry small proactive lifeboats instead of inflatable life rafts. These boats are unsinkable, and can be sailed to safety. Lifeboat drills are required by law on larger commercial ships.

Inflatable lifeboats may be equipped with auto-inflation (carbon dioxide or nitrogen) canisters or mechanical pumps. A quick release and pressure release mechanism is fitted on ships so that the canister or pump automatically inflates the lifeboat, and the lifeboat breaks free of the sinking vessel. Commercial aircraft are also required to carry auto-inflating life rafts in case of an emergency water landing
Water landing
A water landing is, in the broadest sense, any landing on a body of water. All waterfowl, those seabirds capable of flight, and some human-built vehicles are capable of landing in water as a matter of course....

, and are also kept on offshore platforms.

Ship-launched lifeboats are lowered from davit
Davit
A davit is a structure, usually made of steel, which is used to lower things over an edge of a long drop off such as lowering a maintenance trapeze down a building or launching a lifeboat over the side of a ship....

s on a ship's deck, and cannot be sunk in normal circumstances. The cover serves as protection from sun, wind and rain, can be used to collect rainwater, and is normally made of a reflective or fluorescent material that is highly-visible. Lifeboats have oars, flares and mirrors for signaling, first aid supplies, and days' of food and water. Some lifeboats are more capably equipped to permit self-rescue; with supplies such as a radio, an engine and sail, heater, navigational equipment, solar water stills, rainwater catchments and fishing equipment.

The International Convention for the Safety of Life at Sea
International Convention for the Safety of Life at Sea
The International Convention for the Safety of Life at Sea is an international maritime safety treaty. The SOLAS Convention in its successive forms is generally regarded as the most important of all international treaties concerning the safety of merchant ships.- History :The first version of the...

 (SOLAS) and the International Life-Saving Appliance Code (LSA) requires certain emergency equipment be carried on each lifeboat and liferaft used on international voyages. Modern lifeboats carry an Emergency Position-Indicating Radio Beacon
Emergency Position-Indicating Radio Beacon
Distress radio beacons, also known as emergency beacons, ELT or EPIRB, are tracking transmitters which aid in the detection and location of boats, aircraft, and people in distress. Strictly, they are radiobeacons that interface with worldwide offered service of Cospas-Sarsat, the international...

 (EPIRB) and either a radar reflector or Search and Rescue Transponder (SART). In the United States, the US Coast Guard ensures the proper type and number of lifeboats are in good repair on large ships.

Origins

By the turn of the 20th century larger ships meant more people could travel, but safety rules regarding lifeboats remained out of date: for example, British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 legislation concerning the number of lifeboats was based on the tonnage of a vessel and only encompassed vessels of "10,000 gross tons
Long ton
Long ton is the name for the unit called the "ton" in the avoirdupois or Imperial system of measurements, as used in the United Kingdom and several other Commonwealth countries. It has been mostly replaced by the tonne, and in the United States by the short ton...

 and over". It was after the sinking of the RMS Titanic on April 15, 1912, that a movement began to require a sufficient number of lifeboats on passenger ships for all people on board. The Titanic, with a gross tonnage of 46,000 tonnes and carrying 20 lifeboats, met and exceeded the regulations laid down by the Board of Trade
Board of Trade
The Board of Trade is a committee of the Privy Council of the United Kingdom, originating as a committee of inquiry in the 17th century and evolving gradually into a government department with a diverse range of functions...

, which required a ship of her size (i.e. over 10,000 tons) to carry boats capable of carrying a total of 1,060 people. The Titanics boats had a capacity of 1,178 people on a ship capable of carrying 3,330 people.

The need for so many more lifeboats on the decks of passenger ships after 1912 led to the use of most of the deck space available even on the large ships, creating the problem of restricted passageways. This was resolved by the introduction of collapsible lifeboats, a number of which (Berthon Boat
Berthon Boat
Berthon Boats have double linings of canvas, sectioned in two watertight envelopes that assist buoyancy and give protection from the possibility that the outer canvas could be accidentally torn...

s) had been carried on the Titanic.

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...

 and the Battle of the Atlantic with convoys going to northern Russia
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 through the Arctic Ocean
Arctic Ocean
The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region, is the smallest and shallowest of the world's five major oceanic divisions...

 it was found that the chance of the crews of merchant ships surviving in open lifeboats was not very good unless they were rescued in a couple of hours. The US Navy asked various groups and manufacturers to suggest solutions. The results was the first enclosed, unsinkable, self-righting lifeboat that was manufactured in Delanco, New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...

, USA. The first units were delivered in 1944. These radically new lifeboats were 24 feet in length and weighed 5,000 lbs. They had two enclosed cabins at each end which could hold a total of 25 persons. The space in between was designed to help persons in the water be pulled aboard, and could be enclosed with a canvas top. The new type lifeboat could be driven either by a small motor or sail.

Also, in 1943 the US developed a balsa
Balsa
Ochroma pyramidale, commonly known as the balsa tree , is a species of flowering plant in the mallow family, Malvaceae. It is a large, fast-growing tree that can grow up to tall. It is the source of balsa wood, a very lightweight material with many uses...

 wood liferaft that would not sink, irrespective of the number of holes (from enemy fire) in it. These balsa liferafts were designed to hold five to ten men on a platform suspended on the inside or fifteen to twenty-five hanging lines placed on the outsides. They were inexpensive, and during the war thousands were stored in any space possible on US warships and merchant ships. These liferafts were intended only for use during a short term before lifeboats or another ship in the convoy or group could bring them aboard. When the USS Indianapolis
USS Indianapolis (CA-35)
USS Indianapolis was a of the United States Navy. She holds a place in history due to the circumstances of her sinking, which led to the greatest single loss of life at sea in the history of the U.S. Navy...

 operating alone was sunk in 1945, none of its larger lifeboats were launched and instead the survivors had to rely these balsa liferafts which were automatically released as the ship sank. While many of the crew perished, if it had not been for these balsa liferafts it is likely all would have perished.

Today, Enclosed lifeboats are the preferred lifeboats fitted on modern merchant ships, due to their superior protection against the elements (especially heat, cold and rough seas) in case of their deployment.

Generally each merchant ship has one lifeboat fitted on the port side and one on the starboard side. The logic being that a lifeboat is always available irrespective of which side the vessel is listed / heeled over. Lifeboat capacity is pre-determined and pre-defined (volume having been estimated typically via Simpson's rule
Simpson's rule
In numerical analysis, Simpson's rule is a method for numerical integration, the numerical approximation of definite integrals. Specifically, it is the following approximation:...

, from a set of cross-section area measurements)
and mentioned on the ship's "Safety equipment certificate". Further details of the boats are found in "Form E" of this certificate.

Ships fitted with "Free fall" lifeboats are an exception - they have a total of only one boat, located at the stern
Stern
The stern is the rear or aft-most part of a ship or boat, technically defined as the area built up over the sternpost, extending upwards from the counter rail to the taffrail. The stern lies opposite of the bow, the foremost part of a ship. Originally, the term only referred to the aft port section...

 of the ship .

Liferaft versus lifeboat

Liferafts in general are collapsible, and stored in a heavy-duty fiberglass
Fiberglass
Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...

 canister, and also contain some high-pressure gas (in commercial models, usually compressed air
Compressed air
Compressed air is air which is kept under a certain pressure, usually greater than that of the atmosphere. In Europe, 10 percent of all electricity used by industry is used to produce compressed air, amounting to 80 terawatt hours consumption per year....

) to allow automatic inflation to the operations size. SOLAS and military regulations require these to be sealed, never opened by the ship's crew; they are removed at a set periodicity (annually on merchant vessels) and sent to a certified facility to open and inspect the liferaft and contents. In contrast, a lifeboat is open, and regulations require a crewmember to inspect it periodically and ensure all required equipment is present.

Modern lifeboats have a motor; liferafts usually do not. Large lifeboats use a davit or launching system (there might be multiple lifeboats on one), that requires a human to launch. Lifeboat launching takes longer and has higher risk of failure due to human factors. However lifeboats do not suffer from inflation system failures as inflatable liferafts do.

Recently, smaller self-rescue lifeboats have been introduced for use by boats with fewer people aboard: these are rigid dinghies with CO2
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

-inflated exposure canopies and other safety equipment. Like the lifeboats used before the advent of the gasoline engine, these self-rescue dinghies are designed to let the passengers propel themselves to safety by sailing or rowing. In addition to their use as proactive lifeboats, these self-rescue dinghies are also meant to function as yacht tenders.

The International Convention for the Safety of Life at Sea
International Convention for the Safety of Life at Sea
The International Convention for the Safety of Life at Sea is an international maritime safety treaty. The SOLAS Convention in its successive forms is generally regarded as the most important of all international treaties concerning the safety of merchant ships.- History :The first version of the...

 (SOLAS) makes it a requirement for merchant ships to have liferafts on each side of the ship, sufficient for all the people on board (the stated capacity of the lifeboat, irrespective of the fact that there may actually be lesser people onboard). However, if the lifeboats are "easily transferable" (viz. have an open deck between port and starboard lifeboat decks), the number of liferafts may be reduced to a total sufficient for the ships capacity.

The equipment carried in a liferaft is much less than a lifeboat. Vis a vis lifeboats, liferafts are not self righting and have no motor.

Specialized lifeboats

Some ships have freefall lifeboats, stored on a downward sloping slipway, dropping into the water as holdback is released. Such lifeboats are considerably heavier to survive the impact with water. Freefall lifeboats are used for their capability to launch nearly instantly and high reliability, and since 2006 are required on bulk carrier
Bulk carrier
A bulk carrier, bulk freighter, or bulker is a merchant ship specially designed to transport unpackaged bulk cargo, such as grains, coal, ore, and cement in its cargo holds. Since the first specialized bulk carrier was built in 1852, economic forces have fueled the development of these ships,...

s that are in danger of sinking too rapidly for conventional lifeboats to be released.

Tankers are required to carry fireproof lifeboats, tested to survive a flaming oil or petroleum product spill from the tanker. Fire protection of such boats is provided by insulation and sprinkler system, which has pipe system on top, through which water is pumped and sprayed to cool the surface. This system, while prone to engine failure, allows fireproof lifeboats to be built of fiberglass and not only metal.

United States Navy liferafts

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...

 uses five types of custom inflatable life rafts as well as a number of commercially available Coast Guard approved life rafts. The 25-person MK-6 and 50-person MK-7 are used on surface ships, the 50-person MK-8 on aircraft carriers and LRU-13A and LRU-12A on aircraft and submarines respectively. Smaller combatant craft often use 6, 10 or 15-person commercial life rafts. The number of life rafts carried on USN ships is determined based on the maximum number of personnel carried aboard plus 10% as a safety margin. Aircraft carriers carry either 254 MK7 life rafts or 127 MK8 life rafts. While both are similar to heavy-duty commercial life rafts, USN life rafts use breathable air as the inflation gas rather than carbon dioxide to ensure full inflation within 30 seconds in Arctic environments.

Base material used on MK7 life rafts is polyurethane
Polyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...

 coated fabric which has very high durability. Old MK6 and a few MK8 life rafts are manufactured of neoprene
Neoprene
Neoprene or polychloroprene is a family of synthetic rubbers that are produced by polymerization of chloroprene. Neoprene in general has good chemical stability, and maintains flexibility over a wide temperature range...

-coated fabric, however, the majority of MK8 life rafts are also manufactured of polyurethane fabric. The lifeboat is compact and made of separate compartments, or tubes, as a redundancy against puncture. Two air cylinders
Gas cylinder
A gas cylinder is a pressure vessel used to store gases at above atmospheric pressure. High pressure gas cylinders are also called bottles. Although they are sometimes colloquially called "tanks", this is technically incorrect, as a tank is a vessel used to store liquids at ambient pressure and...

 containing dry, breathable compressed air provide initial inflation. Depending on the model life raft, each cylinder may contain up to 5000 psi of compressed air. Each life raft is equipped with an external, automatically actuated light beacon and internal lighting. Power is provided by lithium batteries
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...

.

USN life rafts are stowed in heavy-duty fiberglass canisters and can be launched manually or automatically should the ship begin to sink. Automatic launching and inflation is actuated by a change in pressure sensed by a hydrostatic release device should the ship begin to sink. A hand pump is provided to "top-off" pressure at night when temperatures drop and internal air pressure decreases. Relief valves are installed in each tube to prevent overpressure. Repairs to holes or rips up to six inches in length can be made using special sealing clamps. Occupants in USN life rafts are protected from wind, rain and sun by built-in canopies which automatically inflate. Hatches are sealable to prevent rain and seawater from entering the life rafts. Survival equipment includes: manual reverse osmosis
Reverse osmosis
Reverse osmosis is a membrane technical filtration method that removes many types of large molecules and ions from solutions by applying pressure to the solution when it is on one side of a selective membrane. The result is that the solute is retained on the pressurized side of the membrane and...

 desalinator
Desalination
Desalination, desalinization, or desalinisation refers to any of several processes that remove some amount of salt and other minerals from saline water...

 (MROD), bottles of fresh water, individual food packets
Emergency rations
Emergency rations are items of food and drink that a person stores and relies on in case of an emergency. Emergency food supplies can be purchased for camping trips or wilderness adventures. These supplies are meant to last for several day. Many people also purchase long shelf life emergency food...

, fishing kit, signaling mirror, rocket and smoke flares
Flare (pyrotechnic)
A flare, also sometimes called a fusee, is a type of pyrotechnic that produces a brilliant light or intense heat without an explosion. Flares are used for signalling, illumination, or defensive countermeasures in civilian and military applications...

, flashlight
Flashlight
A flashlight is a hand-held electric-powered light source. Usually the light source is a small incandescent lightbulb or light-emitting diode...

, spare sea anchor
Sea anchor
A sea anchor, is a device external to the boat, attached to the bow used to stabilize a boat in heavy weather. It anchors not to the sea floor but to the water itself, as a kind of brake. Sea anchors are known by a number of names, such as drift anchor, drift sock, para-anchor, and boat brakes...

, first aid kit
First aid kit
A first aid kit is a collection of supplies and equipment for use in giving first aid, and can put together for the purpose , or purchased complete...

, paddles
Oar
An oar is an implement used for water-borne propulsion. Oars have a flat blade at one end. Oarsmen grasp the oar at the other end. The difference between oars and paddles are that paddles are held by the paddler, and are not connected with the vessel. Oars generally are connected to the vessel by...

, spare batteries and bulbs, and aluminized mylar sheets ("space blanket
Space blanket
A space blanket is a blanket used in emergencies to reduce heat loss in a person's body caused by thermal radiation, water evaporation and convection.-Manufacturing:First developed by NASA in 1964 for the US space program, the material consists of a...

s") to aid in caring for victims of hypothermia
Hypothermia
Hypothermia is a condition in which core temperature drops below the required temperature for normal metabolism and body functions which is defined as . Body temperature is usually maintained near a constant level of through biologic homeostasis or thermoregulation...

.

USN inflatable life rafts are serviced every five years. Each life raft is test inflated before repacking. The USN life rafts have a high reliability rate of inflation.

See also

  • Airborne lifeboat
    Airborne lifeboat
    Airborne lifeboats were powered lifeboats that were made to be dropped by fixed-wing aircraft into water to aid in air-sea rescue operations. An airborne lifeboat was to be carried by a heavy bomber specially modified to handle the external load of the lifeboat...

  • Boat
    Boat
    A boat is a watercraft of any size designed to float or plane, to provide passage across water. Usually this water will be inland or in protected coastal areas. However, boats such as the whaleboat were designed to be operated from a ship in an offshore environment. In naval terms, a boat is a...

  • Carley float
    Carley float
    The Carley float was a form of invertible liferaft designed by American inventor Horace Carley . Supplied mainly to warships, it saw widespread use in a number of navies during peacetime and both World Wars until superseded by more modern rigid or inflatable designs...

  • Dinghy
    Dinghy
    A dinghy is a type of small boat, often carried or towed for use as a ship's boat by a larger vessel. It is a loanword from either Bengali or Urdu. The term can also refer to small racing yachts or recreational open sailing boats. Utility dinghies are usually rowboats or have an outboard motor,...

  • Equipment of the United States Coast Guard
    Equipment of the United States Coast Guard
    The United States Coast Guard uses cutters and small boats on the water, and fixed- and rotary wing aircraft in the air. The Coast Guard employs various small arms including handguns, shotguns, rifles, and machine guns.-Cutters:...

  • Lifeboat ethic - An ethic proposed by Garret Hardin based on the metaphor of a lifeboat
  • MES
    Marine evacuation system
    A Marine Evacuation Systems is a lifesaving device found on many modern passenger ships consisting of an inflatable slide or chute where passenger can evacuate straight into waiting life rafts....

     - Marine evacuation system
  • Poon Lim
    Poon Lim
    Poon Lim or Lim Poon BEM was a Chinese sailor who survived 133 days alone in the South Atlantic.-Castaway:...

  • Royal National Lifeboat Institution
    Royal National Lifeboat Institution
    The Royal National Lifeboat Institution is a charity that saves lives at sea around the coasts of Great Britain, Ireland, the Channel Islands and the Isle of Man, as well as on selected inland waterways....

  • Search and Rescue
    Search and rescue
    Search and rescue is the search for and provision of aid to people who are in distress or imminent danger.The general field of search and rescue includes many specialty sub-fields, mostly based upon terrain considerations...

  • Steven Callahan
    Steven Callahan
    Steven Callahan is an American author, naval architect, inventor, and sailor most notable for having survived for 76 days adrift on the Atlantic Ocean in a liferaft...


External links

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