A Life Jacket, also known as a Life Preserver or Life Belt, is a broad beltlike jacket of buoyant material that can be easily secured to the body to keep a person afloat. In 1852 it became mandatory for steamboats carrying passengers to provide a life preserver for each person aboard.
The International Convention for the Safety of Life at Sea 1948 prescribed that an approved life preserver for an' adult must be capaole of supporting 16.5 pounds (7.4 kg) of iron in freshwater for 24 hours, and one for a child must support 11 pounds (5 kg) of iron under the same conditions. The life preserver must be reversible and be capable of holding up the head of the unconscious person. Thus there must be more buoyant material in front than in back, so that the wearer will not tip forward on his face. As specified by the U. S. Coast Guard, a life preserver must be vestlike, with tapes to secure it on either side. The cloth cover must be in not more than two pieces, one for each side.
Life jackets in which the buoyancy depends on air compartments are prohibited for use on boats, although they are carried on airplanes. The U.S. Coast Guard requires that kapok or fibrous glass filler used in life preservers must be protected by electronically sealed vinyl envelopes. This is because tests have shown that such filler materials in contact with high concentrations of gasoline or light oil, under certain conditions, are subject to rapid and serious loss of buoyancy. Unicellular plastic foam is commonly used as a filler in life preservers and ring life buoys.
The International Convention for the Safety of Life at; Sea 1960 prohibits the use of cork or balsa wood in the manufacture of life preservers. In many instances persons leaping from the decks of sinking ships suffered broken necks when they were struck under the chin by the cork or balsa woodblocks upon hitting the water. The 1960 convention also requires that life preservers on vessels on international voyages be equipped with a ball-type whistle attached by a 3-foot (1-meter) lanyard. The whistle can be used to attract attention in the water.
All motorboats less than 40 feet (12 meters) long and not carrying passengers for hire must have an approved life preserver, ring life buoy, buoyant cushion, or buoyant vest for each person on board. All motorboats ranging in length from 40 to 65 feet (12-20 meters) and not carrying passengers for hire must have an approved life preserver or ring life buoy for each person on board.
All motorboats carrying passengers for hire and all vessels over 65 feet (20 meters) long, whether carrying passengers or not, must have an approved life preserver for each person on board. Vessels carrying passengers must also carry 10% additional life preservers suitable for children. Vessels on international voyages must also have additional life preservers for 5% of the persons on board.