Inflatable boat

An inflatable boat is a lightweight boat constructed with its sides and bow made of flexible tubes containing pressurised gas. For smaller boats, the floor and hull beneath it is often flexible. On boats longer than 3 metres/10 feet, the floor often consists of three to five rigid plywood or aluminium sheets fixed between the tubes but not joined rigidly together. Often the transom is rigid, providing a location and structure for mounting an outboard motor.

Some inflatable boats have been designed to be disassembled and packed into in a small volume, so they can easily stored and transported to water when needed. Here the boat when inflated is kept rigid crossways by a foldable removable thwart. This feature allows such boats to be used as liferafts for larger boats or aircraft, and for travel or recreational purposes.

Other terms for inflatable boats are "inflatable dinghy", "rubber dinghy" or "inflatable".

Zodiac is a tradename for a make of inflatable boat, but often has become a genericized tradename used to mean any inflatable boat or RIB.

Types

Inflatable boats may have rubber floors, either plain or inflatable, or they may include steel, wood or aluminium sheets for rigidity. The tubes are made of rubberised, synthetic sheets of Hypalon or PVC to provide light-weight and secure buoyancy. The tubes are often constructed in separate sections, each with a valve to add or remove air, to reduce the effect of a puncture.

Some inflatable boats have an inflated keel to create a "groove" along the line of the hull improving the hull's wave cutting and turning performance. Due to the lightness, it is easy to cause an inflatable boat to start hydroplaning, thus making it faster than the engine would allow when the hull is operating in displacement mode.

A growing use for inflatables is for white water rafting and kayaking, as well as in river, lake and ocean touring. Professional-level rafts and kayaks have existed for many years; since the late 1990s, more affordable inflatable rafts, kayaks (including sea kayaks) and canoes have been developed by European and North American companies. Typically these inflatable boats contain no rigid frame members, so they can be deflated, folded and stored in compact bags.

Repairing

Should a section puncture it can be repaired while still underway. More extensive inflatable boat repairs - due to pinholes, punctures, peeling, leaks or worn fabric - can be done in dry dock using two-stage synthetic rubber coatings (SRC).

Subject to a great deal of wear and tear from the elements - both water and sun - inflatable boats are often replaced when they could be restored or even repaired. Products that aggressively adhere to the damaged Hypalon or PVC shell can fix virtually any surface damage through a unique chemical bonding between the undercoat and topcoat that permanently vulcanizes the two rubber coatings together to make the inflatable as good as new. However since the Hypalon material increases the cost of the inflatable up to 15% not all manufactures provide the option. Some, such as the Brig and the Zodiac brand inflatable boat offer the option between the PVC or the Hypalon which is recommended for environments of increase heat and sunlight.

Uses

Inflatables are commonly between 2 and 7 metres (6 to 21 feet) long and are propelled by outboard motors of 5 to 80 horsepower (4 to 60 kW). Due to their speed, portability and weight, inflatable boats are used as:-
*rescue craft
*dive boats for scuba diving
*tenders for larger boats and ships in port and at sea
*luxury yacht tenders
*recreational water skiing
*for racing
*commercial or recreational fishing
*for military purposes, such as transporting soldiers from a vessel to shore

Inflatables up to 6 metres in length can be towed on trailers on the road.

These boats are often used by special-operations units of the armed forces of several nations, for such purposes as landing on beaches or submarines. They have also be used by special operations soldiers without government sponsorship, such as guerrillas, pirates, and terrorists.

History

Early attempts

There are ancient carved images of animal skins filled with air being used as one-man floats to cross rivers. They were inflated by mouth. Sometimes these images have been wrongly described as ancient scuba.

In 1839 the Duke of Wellington tested the first inflatable pontoons.

Rubber arrives

In 1900 to 1910 the development of rubber manufacturing enabled attempts at producing circular rubber inflatable boats: similar to modern coracles. These were only usable as rafts and could be propelled only by paddling, and they tended to crack at seams and folds due to imperfect manufacture of the rubber.

Titanic and WWI

With the loss of the Titanic in 1912, and World War I losses of ships to submarine-launched torpedoes, the need for inflatable boats was plain.

One cause of the loss of life on the Titanic was the lack of lifeboats. Even if every lifeboat had been completely filled with passengers and crew, there would have been no way to rescue more than half of all the people on board. The first SOLAS treaty was designed to avoid such a disaster happening again. One of its provisions was to ensure that vessels had enough lifeboats to provide every person aboard the vessel with a place. Putting this rule into effect was not difficult with cargo ships: they had small crews and plenty of deck space. Passenger ships had to stack lifeboats on top of each other to able to carry enough to accommodate the large number of passengers and crew. Warships also had large crews and little deck space.

Between the two World Wars, Goodyear found a way to join rubber to other materials. They made life rafts of square-shaped inflated rubber tubes with a rigid floor. Such rafts were to be stacked vertically aboard warships, usually standing on deck and leaning against deck-houses. But conservative thinking from navies held back this new idea.

Pierre Debroutelle's 1937 design was the first known to have its inflatable tube in a U-shape. It was the first boat of its kind to be certified by the French Navy. Its added wooden transom was patented on 10 August 1943. This version was the predecessor of today's inflatable sports and pleasure boats.

World War II

World War II changed everything. Submarine warfare in the Battle of the Atlantic led to casualties among warships and merchant ships. US warships began using rubber life rafts. Since the rubber was much higher quality than 35 years before, the inflatable returned, but this time it was boat-shaped.

In military use inflatable boats were used to transport torpedoes and other cargo. They also allowed troops to make landings in shallow water, and their compact size and storability made overland transport possible.

One of the models, the Zodiac brand inflatable boat, grew to be popular with the military and contributed significantly to the rise of the civilian inflatable boat industry, both in Europe and in the United States. After World War II, surplus inflatable boats were sold to the public. A version of this boat has been adapted by the Marine Mammal Center for use in rescuing injured marine mammals at sea.

Modern inflatables

Inflatable liferafts were also used successfully to save crews of aircraft that ditched in the sea; bombing, naval and anti-submarine aircraft flying long distances over water being much more common from the start of WWII. The PBY Catalina made by Consolidated Aircraft and Canadair seems to have been the first aeroplane to have had an inflatable life boat aboard, first as optional, later as standard equipment. A later version of that inflatable was pressurized by a gas cylinder rather than by mouth. A wire connected to the plane opened the cylinder valve in the inflatable after the life raft was thrown into the water.

Until the middle 1950s inflatables were still rafts in civilian use, hand paddled but the outboard motor came into use in the early 1950s. (The outboard motor was invented in 1909 by Ole Evinrude.)

Also in the 1950s, the French Navy officer and biologist Alain Bombard was the first to combine the outboard engine, a rigid floor and a boat shaped inflatable. The former airplane-manufacturer Zodiac built that boat and a friend of Bombard, the diver Jacques-Yves Cousteau began to use it, after Bombard sailed across the Atlantic Ocean with his inflatable in 1952. Cousteau was convinced by the shallow draught and good performance of this type of boat and used it as tenders on his expeditions.

The inflatable boat was so successful that Zodiac lacked the manufacturing capacity to satisfy demand. In the early 1960s, Zodiac licenced production to a dozen companies in other countries. In the 1960s, the British company Humber was the first to built Zodiac brand inflatable boats in the UK.

Some inflatables have inflated keels whose V-shape help the hull move through waves reducing the slamming effect caused by the flat hull landing back on the surface the water after passing over the top of a wave at speed.

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Rigid-hulled inflatable boat

The modern rigid-hulled inflatable boat (RIB) is a development of the inflatable boat which has a rigid floor and solid hull. The external shape of the hull lets it cut through waves more easily giving a more comfortable ride when travelling fast in rough conditions. The structure of the hull is capable of supporting a more powerful transom mounted outboard engine or even an inboard engine.

Some RIBs may be 14 metres (45 ft) in length and may include inboard steering, luxury features and full cabins.