Rigid-hulled inflatable boat
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A rigid-inflatable boat (RIB) or rigid-hulled inflatable boat, (RHIB) is a light-weight but high performance and high capacity boat constructed with a solid, shaped hull and flexible tubes at the gunwale. The generic design is very stable and seaworthy. The hull provides efficient performance in the water. The inflatable collar means that buoyancy is not lost if a large quantity of water is shipped aboard. The RIB is a development of the inflatable boat.
General characteristics
RIBs are commonly 4 to 7 metres (13 to 24 ft) long, although they can range in length between 2.5 and 18 metres (7.5 and 55 ft).A RIB is often propelled by either by one or more outboard motors or an inboard motor turning a water jet or z-drive. Generally the power of the motors is in the range of 5 to 500 horse power (4 to 400 kW).
RIBs are often used as rescue craft, safety boats for sailing, dive boats or tenders for larger boats and ships. Their shallow draught, high maneuverability, speed and relative immunity to damage in low speed collisions are advantages in these areas.
RIBs up to about 7 metres in length can easily be towed on trailers on the road, making them attractive as leisure craft.
Performance
RIBs are generally designed as hydroplaning hulls. Due to their low weight RIBs often out-perform other similarly sized and powered boats.The maximum speed of the RIB depends on its weight, power and load and can also be severely limited by sea conditions. A typical 6 metre RIB, with six passengers, 110 horsepower engines, in the sea in Beaufort force 2 is very likely to have a top speed of around 30 knots. High performance RIBs may operate with a speed between 40 and 70 knots, depending on the size and weight.
Construction
Hull
The hull can be made of steel, wood, aluminium, or more commonly, a combination of wood for the structure and glass fiber, bare glass fiber, or glass-reinforced plastic (GRP) composite for the shaped and smooth surface. The hull of a RIB is shaped to increase the performance of the boat in the water by optimising its hydroplaning characteristics. "Deep-V" hulls cut through waves easily but require greater engine power to start planing than "shallow-V" hulls, which plane at lower speed but are a more uncomfortable ride.Tubes
The tubes are usually constructed in separate sections, each with a valve to add or remove air, and to reduce the effect of a puncture. The most common materials for the tubes are Polyvinyl chloride, Polyurethane and Hypalon.Polyvinyl chloride
As a material for building tubes, polyvinylchloride (PVC) has the disadvantage of being hard: it lacks flexibility. To make it supple, an additive is used with the polymer. This additive vaporises as the material ages, making the PVC brittle and allowing it to crack easily. A PVC tube is the cheapest option and lasts approximately five years.Polyurethane
Tubes made of polyurethane (PU) are difficult to manufacture and even more difficult to repair. PU has the great advantage of being very tough. It can even be made knife-proof or bulletproof. Unfortunately to make PU airtight, it has to be used in layers, combined with neoprene. The biggest disadvantage with PU is that it ages quickly: thermal and mechanical wear-and-tear and exposure to ultraviolet-light are problems. A high quality PU-made tube lasts 10 to 15 years.PU tubes are often to be found on commercial RIBs, in applications where strength, durability and long life are needed. Replacing the tubes when they wear out, usually costs one third of the complete RIB.
Hypalon
Tubes made of hypalon are easy to manufacture and even easier to repair with simple puncture repair kits.Hypalon is not airtight and so must be combined with neoprene when used to build tubes. Tubes made with hypalon and neoprene layers can easily last 30 years or more.
Although early in its life a PU tube will be stronger than a hypalon/neoprene tube, by the age of 5 years they have similar levels of durability and that is why hypalon/neoprene tubes are often to be found on RIBs that are owned by commercial and high value leisure users.
Other materials
RIB-shaped boats made from aluminium have been built, but these are not technically inflatable boats.Deck house
Larger RIBs are also available with hard-top or even deck houses made of GRP or aluminium.History
Early days
According to All Inflatables [link] the first modern inflatable rafts were made in the 1830s and 1840s.More recently, inflatable boats where built by the US rubber manufacturer Goodyear and the English rubber manufacturer Dunlop, in the first decade the 1900s. Both companies tried using rubber to make a wide variety of items to explore the possibilities of rubber as a manufacturing material.
Those early inflatables looked like big ring with one thick sheet-rubber floor. They were not engine powered. The material was heavy and did not last long when deflated and not in use. After a short while of storing, the rubber tended to crack and fail at the folds. These were no more than rubber-made, inflated rafts. The idea went back onto their designers' shelves.
Motivation
All this changed due to three major historical events: the loss of RMS Titanic, World War I and World War II.One major cause of the huge loss of life in the sinking of 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 approximately half of all the people on board. The first SOLAS treaty was designed to avoid such a disaster happening again. One of its main provisions was to ensure vessels had enough lifeboats to provide every person aboard the vessel with a place in case the vessel had to be abandoned. Putting this rule into effect was not difficult with cargo ship: 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.
With the First World War and its submarine war, the lifeboats again became more important.
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 inflatable. 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.
In WW2 changed everything. Submarine warfare, in the form of the Battle of the Atlantic, lead to many casualties among warships and merchant ships. US warships began using rubber life rafts. Since the rubber was on a much higher quality then 35 years before, the inflatable returned but this time it was boat-shapes.
The Inflatable
Inflatable liferafts were also used successfully to save crews of aicraft 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 made by Catalina 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 orally. A wire connected to the plane opened the cylinder valve in the inflatable after the liferaft was thrown into the water.Until now inflatables were still rafts: other than paddles, no one had put a means of propulsion on an inflatable boat. The engine issue rapidly changed when the outboard motor, which was invented in 1909 by Ole Evinrude, became more widespread in the early 1950s.
Also in the 1950s, the French Navy officer and biologist Dr. 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 Dr. 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. "Zodiac" became the word commonly used in French for inflatable boats and RIBs.
The success of the boat was such that Zodiac lacked the manufacturing capacity to satisfy demand. In the early 1960s, Zodiak licenced production to a dozen companies in other countries. In the 1960s, the British company Humber was the first to built Zodiac inflatables in the UK.
At this stage, to achieve better performanence through the water and a more comfortable ride, some inflatables had underwater, inflated, shaped hulls.
The RIB
The combination of rigid hull and large inflatable buoyancy tubes seems to have been first introduced in 1967 by Tony Lee-Elliott [link], and patented by Admiral Hoare in 1969 after research and development at Atlantic College in Wales. RIBs then were introduced for the first time [link] as lifeboats on the Solent, England in 1970.After the Zodiac patent on this invention expired, the RIB-business took another boom. Today there are some thousand manufacturers of RIBs and inflatables in the world. About fifty RIB manufacturers are accommodated in the UK.
See also
External links
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