Lifeboat (rescue)
A lifeboat is a boat designed to save the lives of people in trouble at sea. The term is used for vessels carried by ships to allow passengers and crew to escape in an emergency. In Britain the term is also used for special shore-based vessels manned by volunteers, designed to quickly reach a ship or individuals in trouble at sea. Both ships' lifeboats and rescue lifeboats may be rigid or inflatable vessels.
The first boat specialized as a lifeboat was tested on the River Tyne on January 29, 1790. William Wouldhave and Lionel Lukin both claimed to be the inventor of the first lifeboat. One example of an early lifeboat was the Landguard Fort Lifeboat of 1821, designed by Richard Hall Gower.
In U.S. waters, rescue-at-sea is part of the duties of the United States Coast Guard, which employs its multipurpose ships and aircraft in this role. The Coast Guard is also responsible for making sure that the proper type and number of lifeboats (American usage) are available and kept in good repair on any large ship. "Lifeboat drills" are a part of a cruise experience.
Inflatable lifeboats, also called life rafts, may be equipped with auto-inflation carbon dioxide canisters or mechanical pumps. A quick release and pressure release mechanism is fitted on board 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. They are also kept on offshore platforms.
Ship-launched lifeboats
These are designed to be lowered from davits on a ship's deck. They are designed to be unsinkable, with buoyancy that cannot be damaged. The cover is a storm shelter and sunshade, can usually collect rainwater, and is visible from the air. They usually carry flares and mirrors for signaling, three days' worth of food and water, oars, an engine, heater and basic navigational equipment. In the military the lifeboat may be referred to as a whaleboats, as until recently this boat did meet the minimal definition of a whaleboat. In recent history the boats have started to be replaced by more modern and capable designs that do not meet this minimal definition. A whaleboat by definition is open, very few civilian lifeboats carried aboard ship are whaleboats, as they have the International orange permanent covers.
The International Convention for the Safety of Life at Sea (SOLAS) and the International Life-Saving Appliance Code (LSA) require a specific list of emergency equipment to be carried on each lifeboat and liferaft used on international voyages. Modern lifeboats should also carry an Emergency Position-Indicating Radio Beacon (EPIRB) and either a radar reflector or Search and Rescue Transponder (SART).
Traditionally lifeboats for passages in the Pacific or Indian Oceans were thought unsafe unless they permitted self-rescue. Thus these traditionally included sailing equipment, navigational equipment, solar water stills, rainwater catchments and fishing equipment. Lifeboats for the North Sea include an electric heater for the engine oil, which is left on in cold weather.
United States Navy Liferafts
The United States Navy uses 25-person and 50-person inflatable life rafts onboard all USN ships. Smaller combatant craft often use 6, 10 or 15-person commercial life rafts. New 25-person life rafts are designated MK7 and are carried aboard all classes of USN ships. Aircraft carriers and some amphibious ships often carry MK8 50-person life rafts which offers substantial weight reduction and additional deck edge space for weapons or other equipment. 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 models are very 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.
Additional survival equipment, including a 35-gallon per day manual reverse osmosis desalinator (MROD) is standard equipment to supplement the limited supply of fresh water carried with other survival supplies. Base material used on MK7 life rafts is polyurethane coated fabric which has very high durability. Old MK6 and a few MK8 life rafts are manufactured of neoprene-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 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.
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 desalinator (MROD), bottles of fresh water, individual food packets, fishing kit, signaling mirror, rocket and smoke flares, flashlight, spare sea anchor, first aid kit, paddles, spare batteries and bulbs, and aluminized mylar sheets ("Space Blankets") to aid in caring for victims of hypothermia.
Liferaft versus Lifeboat
Liferafts in general are collapsible, and stored in a heavy-duty fiberglass canister, and also contain some high-pressure gas to allow automatic inflation to the operations size. SOLAS or Military regulations have these sealed, and never opened by ships crew, they are removed at a set periodicity and set to a certified facility to open and inspect the liferaft and contents. In contrast, a lifeboat is open, regulations require a crewmember to inspect it periodically and ensure all required equipment is present. Lifeboats require some form of a davit or launching system, and that does require human intervention to commence or be involved in the launch process. Modern Lifeboats have some form of a motor; liferafts usually do not have a motor. There might be multiple Lifeboats utilizing the same davits or launching system. The term launching system is utilized is some ships have the life boat stored on a significantly downward sloping slipway- release the holdback and it will slide down into the water. These launching systems are such if launched, return to the launching system requires the ship at a pier and a large crane on the pier is necessary,
Origins of the lifeboats on board ships
By the turn of the 20th Century larger ships meant more people could travel, but safety rules in regard with lifeboats stayed out of date. 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 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 had been installed on the Titanic (see Birthon Boat Company).
The ship's tenders of modern cruise ships are often designed to double as lifeboats.
Also see the discussion in dinghy and liferaft.
Modern life boats
Modern motor life boats (MLB) originated as life boats that had been modified with the addition of an engine and provided more power to get in and out of the swell area inside the surf. They can be launched from shore in any weather and perform rescues further distances out. Older lifeboats relied on sails and oars, which are slower and dependent on wind conditions or manpower. Both types remain in use. All lifeboats of this type generally have modern electronic devices such as radios and radar to help locate the party in distress and carry medical and food supplies for the survivors.
The MLB was initially developed by the United States Life Saving Service in 1899, of which models derived from this hull design remained in use until 1987. The United States Life Saving Service later would become the United States Coast Guard and continue in its original mission of saving lives.
The Royal National Lifeboat Institution (or RNLI) maintains lifeboats around the coasts of the United Kingdom and Republic of Ireland, manned by unpaid volunteers with equipment funded through voluntary donation - web-site at www.rnli.org.uk. Most Scandinavian countries also have volunteer lifeboat societies. The local branch of a society generally schedules practices, maintains a lifeboat and shed, and is contacted by commercial marine radio operators when a rescue is needed.
In Australasia, surf lifesaving clubs operate inflatable rescue boats (IRB) for in-shore rescues of swimmers and surfers. These boats are best typified by the rubber Zodiac and are powered by an outboard motor. The rescue personnel wear wet suits.
The Rigid Hulled Inflatable Boat (RIB) is now seen as the best type of craft for in-shore rescues as they are less likely to be tipped over by the wind or breakers. Specially designed Jet rescue boats have also been used successfully. Unlike ordinary pleasure craft, these small to medium sized rescue craft often have very low freeboard so that victims can be taken aboard without lifting. This means that the boats are designed to operate with water inside the boat hull and rely on flotation tanks rather than hull displacement to stay afloat and upright.
The Dutch lifeboat association (KNRM) has put many efforts in developing jet-driven RIB lifeboats. This has resulted in 3 classes. The largest is the "Arie Visser-class: length 18,80 m, twin jet, 2 x 1000 hp, max. speed 35 kts, capacity 120 persons.
Lifeboats are also operated inland at specific events, organisations such as the Royal Life Saving Society (RLSS UK) provide coverage of rivers, lakes and such like.
Other usages
When the Apollo 13 command module was damaged by an explosion in the service module, the lunar module was used as a lifeboat as it had separate life support, propulsion and guidance systems that remained functional (though it was not a lifeboat in the sense that it was detached from the main vehicle).
The International Space Station is equipped with a "lifeboat" known as the Crew Return Vehicle (CRV). A number of designs have been proposed over the years, but funding issues have prevented a dedicated CRV from being built and deployed. Currently, a Soyuz TMA capsule is used as an interim CRV in case there is a need for an emergency landing of the crew. Because the Station's crew size is limited by the lifeboat size, the Station only has three astronauts on board, instead of the intended eight.
Any small self-contained spacecraft designed to operate as a life-preserving vehicle or escape pod for the crew of a spacecraft in distress might also be termed a "lifeboat", and this usage frequently appears in science fiction.
See also
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