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A lifeboat is a small, rigid or inflatable boat carried for emergency evacuation in the event of a disaster aboard a ship. Lifeboat drills are required by law on larger commercial ships. Rafts (liferafts) are also used. In the military, a lifeboat may double as a whaleboat, dinghy, or gig. The ship's tenders of cruise ships often double as lifeboats. Recreational sailors usually carry inflatable life rafts, though a few prefer small proactive lifeboats that are harder to sink and can be sailed to safety. 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; offshore oil platforms also have liferafts. Ship-launched lifeboats are lowered from davits on a ship's deck, and are hard to sink 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 food and water for several days. 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 (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 (EPIRB) and either a radar reflector or Search and Rescue Transponder (SART). ==Origins== During the Age of Sail, the ship's boats were often also used as lifeboats in case of emergency. In March 1870, answering a question at the House of Commons of the United Kingdom about the sinking of PS ''Normandy'', George Shaw-Lefevre said that 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the turn of the 20th century larger ships meant more people could travel, but safety rules regarding lifeboats remained out of date: for example, British legislation concerning the number of lifeboats was based on the tonnage of a vessel and only encompassed vessels of "10,000 gross tons and over". It was not until after the sinking of the RMS ''Titanic'' on April 15, 1912, that a broader 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, 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 Boats) had been carried on the ''Titanic''. During World War II and the Battle of the Atlantic with convoys going to northern Russia through the Arctic Ocean 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 result was the first enclosed, unsinkable, self-righting lifeboat, manufactured in Delanco, New Jersey, 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.〔(''Popular Science'', April 1944, page 133 )〕 Also, in 1943 the US developed a balsa 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'', a cruiser operating alone, was sunk in 1945, none of its larger lifeboats were launched, and the survivors had to rely on balsa liferafts automatically released as the ship sank; many of the crew perished, but the balsa liferafts saved others; ultimately 316 of 1,196 crew survived.〔(''Semihollow balsa life raft floats with bullet holes'', March 1943, Popular Mechanics )〕 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). Generally each merchant ship has one lifeboat fitted on the port side and one on the starboard side, so that a lifeboat is always available even if the ship is listing to one side. Lifeboat capacity is specified〔 〕 and listed 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 only one boat, at the stern. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lifeboat (shipboard)」の詳細全文を読む スポンサード リンク
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