What is a RIB or RHIB?

A good question! Wikipedia gives a really good unbiased description on the pros and cons of a RIB.

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.

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.

Hull

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.

Tubes

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.

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 20+ years.

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.