One boat, two kinds of structure
A rigid inflatable boat combines a solid hull with an inflated tube, called a collar, running round the edge. Each part does a different job. The hull provides shape, strength and the ability to be driven at speed, while the collar supplies buoyancy, stability and protection from impact. The idea emerged in the early 1960s, a story told in the article on RIB origins, and this article looks at how the structure developed and at the uses it found.
The hull
The earliest rigid inflatables used simple wooden or glass-reinforced plastic hulls. Glass-reinforced plastic (GRP, often called fibreglass) became the usual choice for production boats because it could be moulded into complex shapes and repaired relatively easily. Aluminium hulls came into use in later decades, particularly for boats meant to take heavy use. Some builders moved to composite constructions that used foam cores and fibre laminates to save weight.
Hull shape matters as much as material. Most RIBs use a deep-V form at the bow, which cuts into waves, flattening toward the stern so that the boat can plane. Many designs add steps or strakes, which are ridges along the underside, to help control spray and improve handling. These are the same hydrodynamic ideas used in other planing powerboats, and the RIB’s contribution was to pair them with a soft, forgiving collar.
The collar
The collar is made from fabric coated with synthetic rubber or plastic. Early collars used materials descended from those described in the history of the inflatable boat, and successive generations used tougher coated fabrics. Among the best-known coatings are Hypalon, a synthetic rubber, and polyurethane and PVC, which can be welded as well as glued. Different builders favour different materials, and each has advantages in resisting sunlight, abrasion and chemicals.
The tube is divided into several separate compartments, so that damage to one does not deflate the whole collar. Valves allow each section to be inflated, and the collar is attached to the hull by gluing or bonding a flange or by mechanical fixing. Handholds, grab lines and sometimes seating are attached to the tube. Because the collar sits outside the hull, it also acts as a fender, which is useful when working alongside another vessel.
Engines and propulsion
RIBs were powered at first by outboard motors, and many still are, sometimes in pairs for redundancy. Larger and faster boats often use inboard diesel engines coupled to propellers, sterndrives or waterjets. Waterjets have no exposed propeller, which can make a boat safer for work close to swimmers and shallow water. The choice of engine depends on the job, and has shifted over time as engines became lighter and more reliable.
Military uses
Navies and special forces saw the RIB’s value for fast, shallow-draft work. A ship can carry RIBs on davits or in a stern ramp or a bay, and use them to put boarding teams or small landing parties ashore. Patrol RIBs are used to check vessels in harbours and coastal waters, and the same craft have been adopted by customs and police services. Specially built military RIBs may carry weapons mounts, armour and navigation equipment, but a typical naval RIB remains a small, relatively simple boat. The British Royal Navy, the US Navy and many other forces use the type, and a number of manufacturers specialise in military versions. Naval warship history shows a long tradition of ships’ boats, and the RIB is the modern descendant of the cutter and the pinnace in that role.
Research and polar work
Scientific parties use RIBs for landings and for work close to ships. Oceanographic research vessels carry small boats of this kind for inshore sampling and personnel transfers, while expedition ships in polar regions often use them for shore landings. Icebreaker ships and cruise vessels in cold waters sometimes carry RIBs for the same purpose. Their soft collars cope well with floating ice at the edge of shore, but they are not a substitute for caution, and operators have long needed to account for the effects of cold on crews and equipment.
Commercial uses
In commercial work the RIB has found many roles. Pilot boats, crew-transfer craft serving offshore wind farms and harbour workboats are common examples, and some places use larger RIBs for passenger trips. In sport, RIBs support sailing and diving events as safety and course boats. Because production boats are widely available in sizes from a few metres to well over ten, the type has become a general-purpose utility boat rather than only a rescue craft.
Strengths and limitations
The RIB’s main strengths are stability, speed for its size and tolerance of contact. It has limits as well. A fast open boat exposes its crew to spray and cold, and its collar can be damaged by sharp objects or prolonged sunlight. These are part of the reason that larger lifeboats and patrol vessels remain in use alongside it. In history terms, the RIB represents a successful combination of two older technologies, and its spread across military, scientific and commercial fields shows how adaptable that combination proved to be.