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 design is stable and seaworthy. 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.
[edit] 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 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 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, making them attractive as leisure craft.
[edit] 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, load, and 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. Certain companies operating out of holiday destinations have designed a wave jumper. This is a standard RIB, of about 10 metres in length with two parallel rows of seating down the centre of the craft. It is propelled by two Johnson 200 Horsepower engines, with the aim being to get the craft to roughly 75 knots before jumping 10 ft off the tops of waves.
[edit] Construction
[edit] Hull
The hull is 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 with a more uncomfortable ride.
[edit] 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. Common materials for the tubes are Polyvinyl chloride, Polyurethane and Hypalon.
[edit] Polyvinyl chloride
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 easily. A PVC tube is the cheapest option and lasts approximately five years.
[edit] Polyurethane
Tubes made of polyurethane (PU) are difficult to manufacture and hard to repair. PU has the great 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.
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.
[edit] Hypalon
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. Tubes made with Hypalon and Neoprene layers can 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, which is why Hypalon/Neoprene tubes are often to be found on RIBs that are owned by commercial and high value leisure users.
[edit] Deck house
Larger RIBs can have hard-tops or deck houses made of GRP or aluminium.
[edit] History
- See Inflatable boat - History for earlier history.
The combination of rigid hull and large inflatable buoyancy tubes seems to have been first introduced in 1967 by Tony Lee-Elliott [1], and patented by Admiral Hoare in 1969 after research and development at Atlantic College in Wales. RIBs then were introduced for the first time [2] as lifeboats on the Solent, England in 1970.
After the Zodiac patent on the inflatable boat expired, the RIB business boomed. Today there are about a thousand manufacturers of RIBs and inflatables. About fifty RIB manufacturers are in the UK.
[edit] See also
- Inflatable boat
- Luxury yacht tender
- Outboard motor
- Subskimmer for a RIB that can transform into a submerged Diver Propulsion Vehicle and back.
