Personal flotation device
A personal flotation device (abbreviated as PFD; also referred to as, lifejacket, life preserver, Mae West, life vest, life saver, cork jacket, buoyancy aid, flotation suit, etc.) is a device designed to assist a wearer, either conscious or unconscious, to keep afloat.

Devices designed and approved by authorities for use by civilians (recreational boaters, sailors, canoe
A canoe or Canadian canoe is a small narrow boat, typically human-powered, though it may also be powered by sails or small electric or gas motors. Canoes are usually pointed at both bow and stern and are normally open on top, but can be decked over A canoe (North American English) or Canadian...

ists, kayak
A kayak is a small, relatively narrow, human-powered boat primarily designed to be manually propelled by means of a double blade paddle.The traditional kayak has a covered deck and one or more cockpits, each seating one paddler...

ers, etc.) differ from those designed for use by passengers and crew of aircraft (helicopters, airplanes) and of commercial vessels (tugs
A tugboat is a boat that maneuvers vessels by pushing or towing them. Tugs move vessels that either should not move themselves, such as ships in a crowded harbor or a narrow canal,or those that cannot move by themselves, such as barges, disabled ships, or oil platforms. Tugboats are powerful for...

, passenger ferries, cargo ships). Devices used by military (army, air force, special forces, marines, navy, coast guard) and police and enforcement agencies generally have features not found on civilian or commercial models, for example compatibility with other worn kit (e.g. survival vest, bulletproof vest/body armor, equipment harness, rappelling harness, parachute) and use of ballistic nylon cloth to protect pressurized carbon dioxide (CO2) canisters used for inflating the vest from injuring the wearer if struck by a round from a firearm. The ballistic cloth keeps the fragments from the canister from becoming shrapnel injurious to the user.

PFDs are available in different sizes and different designs purposed for various levels of protection.


A lifejacket is a type of personal flotation device designed to keep your airway clear of the water whether the wearer is conscious or unconscious...

or life vests are mandatory on airplanes travelling over water (in which case they consist of a pair of air cells (bladders) that can be inflated by triggering the release of carbon dioxide gas from a canister—one canister for each separate cell. Or the cells can be inflated "orally" that is by blowing into a flexible tube with a one-way valve to seal the air in the cell). Lifejackets must also be supplied on commercial seafaring vessels, accessible to all crew and passengers and to be donned in an emergency. Not only people wear any type of personal flotation devices, but some are available for dogs to wear.

Flotation devices are also found in near water-edges and at swimming pools. They may take the form of a simple vest
A vest is a garment covering the upper body. The term has different meanings around the world:Waistcoat :. This is called a waistcoat in the UK and many Commonwealth countries, or a vest in the US and Canada. It is often worn as part of formal attire, or as the third piece of a lounge...

, a jacket
A jacket is a hip- or waist-length garment for the upper body. A jacket typically has sleeves, and fastens in the front. A jacket is generally lighter, tighter-fitting, and less insulating than a coat, which is outerwear...

, a full-body suit (one piece coverall), or their variations suited for particular purposes. They are most commonly made of a tough synthetic fiber
Synthetic fiber
Synthetic fibers are the result of extensive research by scientists to improve on naturally occurring animal and plant fibers. In general, synthetic fibers are created by forcing, usually through extrusion, fiber forming materials through holes into the air, forming a thread...

 material encapsulating a source of buoyancy, such as foam
-Definition:A foam is a substance that is formed by trapping gas in a liquid or solid in a divided form, i.e. by forming gas regions inside liquid regions, leading to different kinds of dispersed media...

 or a chamber of air, and are often brightly colored as yellow or orange to maximize visibility for rescues. Some devices consist of a combination of both buoyancy foam and an air chamber. Retroreflective "SOLAS" tape is often sewn to the fabric used to construct lifejackets and PFDs to facilitate a person being spotted in darkness when a search light is shone towards the wearer.
Per federal regulations all persons under the age of 13 are required to a life jacket (PFD) when in a watercraft under 12 meters.State regulations may raise or lower this number and must be followed when in that states jurisdiction.

Buoyancy aid (Foam Core)

The simplest and least buoyant type of PFD comes in the form of nylon
Nylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station...

-lined foam
-Definition:A foam is a substance that is formed by trapping gas in a liquid or solid in a divided form, i.e. by forming gas regions inside liquid regions, leading to different kinds of dispersed media...

 vests, used predominantly in watersports such as kayak
A kayak is a small, relatively narrow, human-powered boat primarily designed to be manually propelled by means of a double blade paddle.The traditional kayak has a covered deck and one or more cockpits, each seating one paddler...

ing, canoe
A canoe or Canadian canoe is a small narrow boat, typically human-powered, though it may also be powered by sails or small electric or gas motors. Canoes are usually pointed at both bow and stern and are normally open on top, but can be decked over A canoe (North American English) or Canadian...

ing and dinghy sailing
Dinghy sailing
Dinghy sailing is the activity of sailing small boats by using five essential controls:* the sails* the foils ....


Buoyancy aids are designed to allow freedom of movement while providing necessary buoyancy to a user. They are also designed for minimal maintenance and as they are only constructed from foam
-Definition:A foam is a substance that is formed by trapping gas in a liquid or solid in a divided form, i.e. by forming gas regions inside liquid regions, leading to different kinds of dispersed media...

, can be mass-produced inexpensively making them one of the most commonly seen form of PFDs.

Buoyancy aids also come designed especially for children. These vests feature crotch straps designed to be worn between the legs of the wearer and also a headrest flap.

The crotch straps are designed to keep the vest from riding up when worn in the water, and possibly the wearer from completely slipping out of the life vest. The strap is adjustable and should be sized to fit snugly between the wearer's legs, tight enough to hold the vest low on the wearer so they are not choked by the vest rising up because of its buoyancy, but loose enough so the wearer may swim comfortably, not feeling constrained by the vest. This strap is included life vests designed to be worn by 30–60 lb (13.6–27.2 kg) children and on some vests designed to be worn by people 60–90 lb (27.2–40.8 ) as well. This strap should be worn at all times to eliminate the chance of the wearer slipping out of the vest.

The headrest flap is designed to help support the head and keep it out of the water. A grab handle is attached to the headrest to, if needed, rescue or lift the wearer up, or simply to carry the vest itself.


Lifejackets for outfitting large commercial transport in potentially dangerous waters, such as coastal cruises and offshore passages, and overwater air flights, are either a single air chamber or a pair of (twin or double) sealed air chambers constructed of coated nylon (sometimes with a protective outer encasing of heavier, tougher material such as vinyl
A vinyl compound is any organic compound that contains a vinyl group ,which are derivatives of ethene, CH2=CH2, with one hydrogen atom replaced with some other group...

), joined together (but can also be constructed of foam aboard ships). Twin air chambers provide for redundancy in the event of one of the air chambers leaking or failing to "fire", for example if the thin air cell fabric is sliced open by sharp metal fragments during emergency evacuation and egress. The majority of lifejackets found in leisure use will be single air chamber type.

Aircraft devices for crew and passengers are always inflatable since it may be necessary to swim down and away from a ditched or submerged aircraft: inflated or foam filled devices would significantly impede a person from swimming downward in order to escape a vehicle cabin. Upon surfacing, the person would then inflate the device, orally or by triggering the gas canister release mechanism.

"True" lifejackets always provide more buoyancy than buoyancy aids and the positioning of the buoyancy on the wearer's torso is such that a righting moment (rotational force) is developed that will eventually float most persons (for example unconscious) who are face down into a FACE UP attitude with their bodies inclined backward, unlike common foam buoyancy vests (which are simply swimmers' aids, really since they don't generate re-righting moment forces.) Self righting devices are best for non-swimmers, who may not be able to orient themselves face up in the water, for example due to panic arising from finding themselves in deep, open water.

Today these air chamber vests are commonly referred to as "inflatable lifejackets or vests" and are available not only for commercial applications but also for recreational boating, fishing, sailing, as well as kayaking and canoeing. They are available in a variety of styles and are generally more comfortable and less bulky than traditional foam vests.

The air chambers are always located over the breast, across the shoulders and encircling the back of the head. They may be inflated by either self-contained carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 cartridges activated by the pulling of a cord, or blow tubes with a one-way valve for inflation by exhalation
Exhalation is the movement of air out of the bronchial tubes, through the airways, to the external environment during breathing....

. Some of the inflatable lifejackets also react with the salt/fresh water, inflating them. The latest generation of self triggering inflation devices, however, respond to water pressure when submerged and incorporate an actuator known as a "hydrostatic release". Regardless of whether manually (pull cord) or automatically triggered, a pin punctures the cartridge/canister and the CO2 gas escapes into the sealed air chamber.
However, there is a chance that these water pressure activated inflation devices do not inflate the lifejacket if a person is wearing waterproof clothing and falls into the water face-down. In these cases the buoyancy of the clothing can hold a person on the water surface and avoids the hydrostatic release. As a result a person can drown although the lifejacket is fully functional. To be on the safe side, a pill activated inflation device should be preferred. A little pill that dissolves with water contact is in fact the safest option as it also works in shallow waters where the hydrostatic activator fails. This type of jacket is called an automatic. As it is more sensitive it used to be the case that this style of automatic system was more likely to activate during very heavy rain or spray. However, with modern cup/bobbin mechanisms this is now a rarity and some mechanisms such as the Halkey Roberts Pro firing system have all but eliminated this accidental firing.. Spare re-arming kits should always be carried for any lifejacket you have onboard.

Drifting in open seas and international waters, as encountered by long sea voyages and military
A military is an organization authorized by its greater society to use lethal force, usually including use of weapons, in defending its country by combating actual or perceived threats. The military may have additional functions of use to its greater society, such as advancing a political agenda e.g...

 forces, require prolonged survival in water. The lifejackets suited for this purpose are often attached to a vest with pockets and attachment points for distress signaling and survival aids, for example: a handheld two-way radio (walkie-talkie), emergency beacon (406 MHz frequency), signal mirror, sea marker dye, smoke or light signal flares, strobe light, first-aid supplies, concentrated nutritional items, water purification supplies, shark repellent, knife, pistol.

Offshore sailors and others can utilize accessories such as leg straps to keep the inflated chambers in position for floating in a stable attitude and splash or face shields constructed of clear see-through vinyl which covers the head and face to ward off water from waves inundating the face (nasal and mouth entries to the airway).

Survival suit

Some formats of PFDs are intended for long term immersion in cold water in that they provide insulation as well as buoyancy. While a wetsuit
A wetsuit is a garment, usually made of foamed neoprene, which is worn by surfers, divers, windsurfers, canoeists, and others engaged in water sports, providing thermal insulation, abrasion resistance and buoyancy. The insulation properties depend on bubbles of gas enclosed within the material,...

 of neoprene rubber and divers' drysuits provide a degree of flotation, they are not formally considered by regulatory agencies as approved lifesaving devices or as PFDs, in most maritime countries.

Note that it is possible for an incapacitated person in the water to float face-down while wearing simply a wet suit or a dry suit since they are not designed to serve as lifesaving devices in the normal use of that term.

The Mark 10 Submarine Escape Immersion Equipment
Submarine Escape Immersion Equipment
Submarine Escape Immersion Equipment MK-10, also known as Submarine Escape and Immersion Equipment is whole-body suit and one-man life raft, designed by British company RFD Beaufort Limited, that allows submariners to escape from a sunken submarine. The suit provides protection against hypothermia...

 (SEIE) suit is intended to allow submariners to escape from much deeper depths than currently possible with the Steinke hood
Steinke hood
A Steinke hood, named for its inventor, Lieutenant Harris Steinke, is a device designed to aid escape from a sunken submarine,essentially an inflatable life jacket with a hood that completely encloses the wearer's head, trapping a bubble of breathing air...

. Some 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...

 submarines already have the system, with an ambitious installation and training schedule in place for the remainder of the fleet.

Because it is a full-body suit, the Mark 10 provides thermal protection once the wearer reaches the surface, and the Royal Navy has successfully tested it at 180 m
The metre , symbol m, is the base unit of length in the International System of Units . Originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole , its definition has been periodically refined to reflect growing knowledge of metrology...

 (600 foot) depths. (see Submarines in the United States Navy#Pressure and escape training and Steinke hood
Steinke hood
A Steinke hood, named for its inventor, Lieutenant Harris Steinke, is a device designed to aid escape from a sunken submarine,essentially an inflatable life jacket with a hood that completely encloses the wearer's head, trapping a bubble of breathing air...


Buoyancy compensator

SCUBA divers commonly wear a "BC" or buoyancy compensator, which involves an inflatable gas chamber. The amount of gas can be increased or decreased to enable the diver to ascend, descend or maintain neutral buoyancy at a given water depth and to provide positive buoyancy in an emergency to bring them to the surface or keep them at the surface.


Specialized life jackets can also be seen used in a myriad of environments. Shorter-profile vests are commonly used for kayaking
Kayaking is the use of a kayak for moving across water. Kayaking and canoeing are also known as paddling. Kayaking is distinguished from canoeing by the sitting position of the paddler and the number of blades on the paddle...

 (especially playboating
Playboating is a discipline of whitewater kayaking or canoeing where the paddler performs various technical moves in one place , as opposed to downriver whitewater canoeing or kayaking where the objective is to travel the length of a section of river...

), and high-buoyant types for river outfitters and other whitewater professionals. PFDs which include harnesses for tethered rescue work ('live-bait rescue') and pockets or daisy-chains (a series of loops created by sewing flat nylon webbing at regular intervals) for the attachment of rescue gear are made for swiftwater rescue technicians
Swiftwater rescue
Swiftwater rescue is a subset of technical rescue dealing in whitewater river conditions. Due to the added pressure of moving water, swiftwater rescue involves the use of specially trained personnel, ropes and mechanical advantage systems that are often much more robust than those used in standard...


PFD's for pets

While the USCG does not approve personal floatation devices for animals, many manufactures produce lifejackets for dogs and cats. Every year dogs and cat die from downing; either they don’t know how to swim, too dense, tire out from over exposure or old age, or from a medical complication such as a seizure. They also could be knocked into the water and simultaneously knocked unconscious. It is important to protect your pets by providing them the same safety equipment you would give to a child or elderly person.

Most lifejackets on the market are designed around foam that wraps around the body and some also go around the neck. These provide a basic amount of buoyancy for a dog but do not provide a lot of support for the head and are not especially good with very dense dogs like bull dogs.

There is one item on the market that is an automatically inflatable lifejacket for pets made by Critter’s Inflatable, LLC. This device is more expensive than a traditional foam lifejacket, but like the ones designed for people are much less bulky and more comfortable to wear when uninflated and when inflated provide more buoyancy than the foam counter parts. These lifejackets are very popular in the bull dog community and also for water therapy where a lot of support is needed under the head.


The most ancient examples of "primitive life jackets" can be traced back to inflated bladders of animal skins or hollow, sealed gourds, for support when crossing deeper streams and rivers.

Personal flotation devices were not part of the equipment issued to naval sailors up to the early 19th century, for example at the Napoleonic Battle of Trafalgar. Seamen who were press-ganged into naval service might have used such devices to jump ship and swim to freedom. It wasn't until lifesaving services were formed that personal safety of boat crews heading out in pulling boats generally in horrific sea conditions was addressed.

Purpose-designed buoyant safety devices consisting of simple blocks of wood or cork
Cork (material)
Cork is an impermeable, buoyant material, a prime-subset of bark tissue that is harvested for commercial use primarily from Quercus suber , which is endemic to southwest Europe and northwest Africa...

 were used by Norwegian
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

 seamen. The modern lifejacket is generally credited to one Captain Ward, a 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....

  inspector in the United Kingdom
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...

, who, in 1854, created a cork vest to be worn by lifeboat
Lifeboat (rescue)
A rescue lifeboat is a boat rescue craft which is used to attend a vessel in distress, or its survivors, to rescue crewmen and passengers. It can be hand pulled, sail powered or powered by an engine...

 crews for both weather protection and buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...


The rigid cork material eventually came to be supplanted by pouches containing watertight cells filled with kapok
Ceiba pentandra is a tropical tree of the order Malvales and the family Malvaceae , native to Mexico, Central America and the Caribbean, northern South America, and to tropical west Africa...

, a vegetal material. These soft cells were much more flexible and more comfortable to wear compared with devices utilizing hard cork pieces. Kapok buoyancy was used in many navies fighting in the Second World War. Foam eventually supplanted kapok for "inherently buoyant" (vs. inflated and therefore not inherently buoyant) flotation.

Reference: Built for Life: the history of lifejackets; Dr. Christopher Brookes, Defence and Civil Institute for Environmental Medicine (Downsview , Ontario, Canada; Canadian Navy); Survival Systems (Halifax, Nova Scotia, Canada) [apparently the only authoritative text on the subject in the English language with a comprehensive account of lifejackets; the only others are in German] in 1878 they were called life belts.

The University of Victoria in British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

 pioneered research and development into the "Floater Coat" (patented UVic Thermo Float PFD), which provides superior protection from cold water immersion (immersion hypothermia) through the incorporation of a neoprene rubber "diaper" that seals the user's upper thigh/groin region from otherwise cold, flushing and debilitating water.

Mae West

The Mae West was a common nickname for the first inflatable life preserver, which was invented in 1928 by Peter Markus (1885–1974) (US Patent 1694714) with his subsequent improvements in 1930 and 1931. The nickname was originated because someone wearing the inflated life preserver often appeared to be as physically endowed as the actress Mae West
Mae West
Mae West was an American actress, playwright, screenwriter and sex symbol whose entertainment career spanned seven decades....

 as well as rhyming slang for breast. It was popular during the 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...

 with U.S. Army Air Forces and 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...

 servicemen, who were issued inflatable Mae Wests as part of their flight gear. Air crew members whose lives were saved by use of the Mae West (and other personal flotation devices) were eligible for membership in the Goldfish Club
Goldfish Club
The Goldfish Club is a worldwide association of people who have jumped by parachute from an aircraft into the water, or whose aircraft crashed in the water, and whose lives were saved by a life jacket, inflatable dinghy, or similar device...


During the war, research to improve the design of life jackets was also conducted in the UK by Edgar Pask OBE, the first Professor of Anaesthesia at the Newcastle University. Some of his research involved self-administered anaesthesia as a means of simulating unconsciousness
Unconsciousness is the condition of being not conscious—in a mental state that involves complete or near-complete lack of responsiveness to people and other environmental stimuli. Being in a comatose state or coma is a type of unconsciousness. Fainting due to a drop in blood pressure and a...

in freezing sea-water. Pask's work earned him the OBE and the description of "The bravest man in the RAF never to have flown an aeroplane".

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.