A rigid-hulled inflatable boat, (RHIB) or rigid-inflatable boat (RIB) is a light-weight but high-performance and high-capacity boat constructed with a solid, shaped hull and flexible tubes at the gunwale. The design is stable and seaworthy. The inflatable collar allows the vessel to maintain buoyancy even if a large quantity of water is shipped aboard due to bad sea conditions. The RIB is a development of the inflatable boat.
Uses include work boats (supporting shore facilities or larger ships) in trades that operate on the water, as well as use as lifeboats and military craft, where they are used in patrol roles and to transport troops between vessels or ashore.
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The combination of rigid hull and large inflatable buoyancy tubes seems to have been first introduced in 1967 by Tony and Edward Lee-Elliott of Flatacraft,[1][2] and patented by Admiral Desmond Hoare in 1969 after research and development at Atlantic College in Wales.
In 1964, Rear-Admiral Desmond J. Hoare and his students at Atlantic College in South Wales replaced the torn bottom of their 12-foot-long (3.7 m) sailing club rescue inflatable boat by a plywood sheet glued to the inflatable tubes. This proved a successful modification but was rather uncomfortable at speed offshore and so the floor was rebuilt with a deep-vee bow blending to a nearly flat section stern. This boat was named Atlanta and later that year an Atlantic College RIB was displayed at the London Boat Show.[3]
By 1966 the students had built a further five rigid inflatable boats – Aphrodite (15 ft), Triton (16 ft) and X1–X3. Aphrodite and Triton were for the College’s own use. X1 (16 ft) and X2 (22 ft) were launched in 1965 by Queen Elizabeth II and made under a development agreement with the UK Royal National Lifeboat Institution (RNLI). They were taken by the RNLI for trials at Gorleston (X1) and Great Yarmouth (X2) from which they returned to Atlantic College in spring 1967. X3 was an experimental vortex-lift hull funded by a private developer and was not greatly successful.
By that time Des Hoare had concluded that for the conditions under which they operated a boat of around 18 feet long was optimum which led to X4 (launched 1966), X5 and X6 (launched 1967), and X5 to X8 (launched 1968). These boats were used to support the college's sailing activities and also to fulfil the college's responsibility as an inshore lifeboat station for the RNLI – a responsibility it still discharges to this day. At the same time work started on a smaller series of beach-launchable boats (10 – 12 ft long, designated MX1 – MX6) to support lifeguards on local beaches.
All the above boats’ hulls were built from plywood. In summer 1968, student Paul Jefferies designed and constructed a hull (X10) from fiberglass, which was not a success due to lack of strength. However that development led to the building of Psychedelic Surfer,[4] a twin-engined 21 ft RIB, for John Caulcott, Graeme Dillon and Simon de’Ath to race in the 1969 Round Britain Powerboat Race, in which it was one of the few boats to finish.
From that time, the RNLI transferred development to its research centre in Cowes, who took the Atlantic College designs and developed from them the 21 ft Atlantic 21 class of inshore lifeboats which entered service in 1972 and continued for the next 30 years or so.[5]
The first commercial RIB is believed to be the Avon Rubber Co Searider which was launched at the January 1969 London Boat Show.
In the mid-1970s a hull mold and tubes for 21-foot R-HIBs were sent from Atlantic College to their new sister school being established on the west coast of Canada, the Lester B. Pearson College of the Pacific, at Pedder Bay, British Columbia. 3 graduates of the Atlantic College who were also trained as RNLI inshore lifeboat coxswains worked at the school during its inaugural year and coached some Pacific College students to build a pair of boats, designated X-27, propelled by twin outboard engines and X-28, propelled by inboard-outboard stern drive. These students were also trained by the graduates to operate these craft as safety boats in support of the college's coastal sailing and diving programs.
During summer, the college loaned their fast rescue craft to the Canadian Coast Guard (CCG), which was introducing rigid-hull inflatables into its new summer seasonal inshore rescue boat service operation. Meanwhile, the Great Lakes branch of the CCG introduced 5.4 metre Avon Seariders into its regional inshore rescue boat service in the late 1970s. Both branches hired university students to serve as crew, in part due to the success of the student crews operating these ever-buoyant rescue craft at Atlantic and at Pearson College.
RIBs are commonly 4 to 9 metres (13 to 28 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 one or more outboard motors or an inboard motor turning a water jet or stern drive. Generally the power of the motors is in the range of 5 to 300 horse power (4 to 220 kW).
RIBs are 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 applications.
RIBs up to about 7 metres in length can be towed on trailers on the road; this, coupled with their other properties, is making them increasingly attractive as leisure craft.
RIBs are designed with hydroplaning hulls. Due to their low weight, RIBs often outperform some types of similarly sized and powered boats, although a pure fibreglass speedboat with similar dimensions is typically faster, due to its lighter weight and more arrowlike-shape.
RIBs can also generally cope better with rougher seas, although this may be partially due to an increased level of confidence, in knowing that a RIB is hard to sink, and better absorption of heavy loads by the flexible tubes, which therefore make heavy seas less unpleasant.[6]
The maximum speed of the RIB depends on its gross weight, power, length and profile of hull, and sea conditions. A typical seaborne 6-metre (19 ft 8 in) RIB, with six passengers, 110 horsepower (82 kW) engines, in Beaufort force 2 is very likely to have a top speed of around 30 knots (56 km/h). High-Performance RIBs may operate with a speed between 40 and 70 knots (74 and 130 km/h), depending on the size and weight.
The hull is made of steel, wood, aluminium, or more commonly, a combination of wood for the structure and glass-reinforced plastic (GRP) composite for the shaped and smooth surface. Some manufacturers also weave Kevlar into the GRP sheets for extra strength. 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 with a more uncomfortable ride. As with the design of most boat hulls they represent a compromise of different design characteristics. Modern "all round" RIB hulls combine a deep v hull at the bow which flattens out to present a broad planing pad. This is a flat area on the rear of the hull designed to allow the boat to have a stable surface to plane on.
The tubes are usually constructed in separate sections to reduce the effect of a puncture, each with a valve to add or remove air. Larger boats (7m+) have 6 or more chambers with a valve for each chamber. The more chambers a boat has the more redundancy the boat is considered to have. This is because if only one chamber is damaged then the impact the damage has on the boat is much less. Dark tubes often have pressure relief valves as the air inside them expands when exposed to sunlight. This prevents the tubes bursting from over pressure. Common materials for the tubes are Hypalon and uPVC (Polyvinyl chloride), though some manufacturers use PU (Polyurethane).[7]
Tubes made of Hypalon are easy to manufacture and can be repaired with simple puncture repair kits. Hypalon is not airtight and so must be combined with Neoprene when used to build tubes.[8] Tubes made with Hypalon and Neoprene layers can last 20+ years.[8]
Although early in its life a PU tube will be stronger than a Hypalon/Neoprene tube, by the age of five years they have similar levels of durability, which is why Hypalon/Neoprene tubes are often to be found on RIBs that are owned by commercial and high-value leisure users. Hypalon is probably the most popular material used for the construction of RIBs manufactured in the UK.
As a material for building tubes, polyvinylchloride (PVC) has the disadvantage of lacking 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. A PVC tube is the cheapest option and can last approximately 10–15 years.[8]
Tubes made of polyurethane (PU) are difficult to manufacture and hard to repair and are consequently not often used for RHIB construction. PU has an advantage of being very tough, it can 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.[8]
Larger RIBs can have hard-tops or wheelhouses made of GRP or aluminium. Wheelhouses offer protection from the elements to both the crew and passengers - and can also protect equipment such as suspension seats and navigation equipment. Some RIB manufacturers, particularly those popular in Ireland and the West Coast of Scotland provide optional canopies which form fabric and perspex wheelhouses but can be easily removed in good weather. Increasingly, RIBs are becoming available with small cabins (usually with accommodation for two people and in some cases sea toilets or chemical toilets), widening the application of RIBs as cruising craft.
A flying inflatable boat or FIB is a RIB with microlight-type wings and air propeller.[9]