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Life Rafts/Boats

In the 1950s, use of inflatable life rafts became widespread in the maritime community, when large ships began to carry them as spare survival crafts. These early inflatable rafts could automatically float free of a sinking ship, inflate and be ready for use if lifeboats could not be used. By 1960, life rafts became mandatory for passenger and cargo ships.

In 1974, the International Convention on Safety of Life at Sea, or SOLAS, required cargo ships to have enough life rafts to accommodate half of the people permitted on board the ship. These were float-free life rafts intended to be used in the event that lifeboats were unavailable. Drafters of the 1983 SOLAS treaty, agreeing that not providing life rafts for the remaining 50 percent of crew members could lead to a Titanic-style disaster, mandated enough rafts for all on board.

Inflatable life rafts have also increased safety on smaller ships, which have limited space. Most modern units have carbon dioxide cylinders that automatically inflate the raft. Due to the increased reliability of these rafts, the 1983 SOLAS treaty allowed cargo ships shorter than 280 feet in length and passenger ships carrying fewer than 200 passengers the option of carrying only life rafts (no lifeboats), as long as they were in sufficient numbers to accommodate everyone on board. Since these life rafts have no means of propulsion, these ships must carry at least one rescue boat, which facilitates man-overboard rescues, assists other ships in distress, and tows life rafts away from danger.

From its start as a spare survival craft on ocean-faring ships, modern self-inflating life rafts have become much more prevalent in sea safety. In some cases they have even been used to replace the traditional lifeboat.

As for lifeboats, several totally enclosed lifeboats—better known as TEMPSC's, for Totally Enclosed Motor Propulsed Survival Craft—were designed and built as early as the first decade of this century. The conventionally hulled, self-righting "Lundin housed lifeboat" was built, for instance, in 1914. Another designed by Ole Brude, a pioneer in the field, looked something like a torpedo and, instead of being lowered by wires, slid off the low side of the ship on rails. In spite of the obvious advantages of the totally enclosed lifeboat, these heavy, expensive steel boats never caught on.

To battle the hypothermic effects of cold climate sea emergencies as well as to solve the dilemma of deep sea oil rig evacuations, the Totally Enclosed Motor Propulsed Survival Craft was developed to provide shelter for its passengers.

It was only in the 1960s, when transportation and seafloor drilling of oil grew dramatically, that TEMPSC's became a necessity. A number of countries began working on versions that would be able to travel for five or ten minutes through fire on water. Eventually, designers determined that TEMPSC's should be made of fiberglass-reinforced plastic and equipped with an exterior water spray system and an interior air supply system for the engine and occupants.

Following two serious sea disasters in 1973, the design of lifeboat launching systems underwent closer scrutiny. The result was the free-fall lifeboat. Relying on TEMPSC technology, Joost Verhoef developed an inclined launching system which, using the natural force of gravity, would allow a totally enclosed lifeboat to simply slide down a ramp and plunge into the water below. Today, free-fall TEMPSC's have been tested at heights of up to nearly 100 feet. They are found on many tankers and most mobile offshore drilling rigs.
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Life Jackets

A demonstration of the Victorian cork vest. Despite its buoyancy, the life vest would fail to keep the head of the passenger, if unconscious and face down, above water.

Early life jackets, fashioned in the Victorian era, were made of cork. Worn by lifeboat crews during rescues, they were effective at keeping men afloat. However, they had a major failing. Since buoyancy was equally distributed around the body, if a person became unconscious and lay facedown in the water, he would remain in that position and would drown. Further, the lack of neck support would result in a person who was losing consciousness to drop his or her head forward, again usually resulting in drowning.

Life jackets came into their own after the heroic tests of Dr. Edgar Pask. In order to determine how an unconscious person floated, Pask allowed himself to be anaesthetized and immersed in water wearing only a standard life jacket and a breathing tube. Pask's daring experiments revealed that the best position for the body to be in when bobbing in the ocean is leaning back with the head at a 45-degree angle to the sea surface.

The modern life vest incorporates an inflated collar, which props the wearer's head above water, and a splashguard, which prevents water from entering the airways of an unconscious wearer.

Modern life jackets are designed with this in mind. A splint braces the neck, and all of the buoyancy lies in the front of the body. In addition, a splash guard is fitted to the front of the life jacket. If a person can pull it out before losing consciousness, the splash guard will block any incoming splashing water from blocking the airways.
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Radio Beacons

Lifeboats and life rafts keep people out of the water until they can be rescued, but how do rescuers know where to find them or even know that there has been a casualty? In the past, many ships carried portable lifeboat radios, but they could weigh 40 pounds or more and be difficult to operate.

A modern innovation to replace the often clumsy and confusing lifeboat radio, Emergency Position-Indicating Radio Beacons (EPIRBs) allow life rafts and lifeboats to emit a radio signal, which can be picked up by aircraft and satellites in order to pinpoint their position.

In 1975, the United States began requiring its large oceangoing merchant ships to carry emergency position-indicating radio beacons (EPIRBs). These devices are designed to float free of a sinking ship and automatically send a distress signal on aircraft distress frequencies. Depending on its altitude, an overflying aircraft can pick up the signal and either alert rescue forces or enable them to home in on the beacon.

The 1983 SOLAS treaty contained a new EPIRB requirement for two EPIRBs on either side of a ship. These EPIRBS are intended to be carried to one of the lifeboats or life rafts on that side of the ship, where they will provide a signal for rescuers to home in on.

In 1988, SOLAS amended its regulations to include satellite EPIRBs within its search-and-rescue procedures. Satellite EPIRBs send a signal that is received by U.S. and Russian weather satellites, and relayed to ground stations. As the satellite passes overhead, the digital data and frequency change of the distress signal are used to identify and pinpoint the vessel in distress. Morse code, which has long been used for distress communications at sea, has now been phased out.
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Immersion Suits

To prevent individual survivors from getting hypothermia, buoyant immersion suits were invented as an improvement to standard life vests in icy waters. Above is a demonstration of the immersion suit in action.

Water transfers heat from the human body 25 times faster than air of the same temperature. In cold water, heat is removed faster than the body can replace it. The result is that the victim eventually becomes helpless and either drowns or succumbs to the effects of hypothermia itself. To prolong survival time in cold water, it is necessary to keep water from coming into contact with the skin and to provide insulation between the water and the skin.

Attempts to provide protection against hypothermia are not new. The use of rubber suits dates back to the early part of the century. Although these suits are credited with having saved lives, they were heavy, they generally required a life jacket to be worn underneath, and they tended to leak and fill with water. The danger they posed in terms of lost thermal protective value and added weight for victims trying to climb out of the water spurred the development, during WWII, of lighter-weight suits made of synthetic rubber.

The modern immersion suit incorporates the use of neoprene fabric to allow the wearer to sustain body heat and flotation.

It took modern materials to make today's "exposure suit" a practical reality. The material that made the difference was neoprene foam sheeting. This material, which first came into use for divers' wet suits, is a closed-cell foam made up of individual air cells, so it floats and also provides excellent thermal insulation. With a nylon fabric bonded to each side to protect the foam, this material is ideal.

Since 1983, small cargo ships that carry inflatable life rafts as their only survival craft and require survivors to jump from the deck to the rafts have stocked immersion suits for everyone on board. Larger ships with conventional open lifeboats have had to carry only three immersion suits for each lifeboat. These are for the crew operating the lifeboat; passengers in the boat have "thermal protective aids," a type of orange, aluminized suit.
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Photos/Illustrations: (1) Zodiac International; (2) Norsafe AS; (3,4) NOVA/WGBH Educational Foundation; (5) Prosat Technologies; (6,7) Imperial International, Inc.

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