Rigid Inflatable Boat

Overview

A rigid inflatable boat, or RIB, combines a solid moulded hull with an inflatable tube running around its upper edge. The rigid hull gives the boat a true planing shape that cuts through waves and holds course at speed, while the inflatable collar adds buoyancy, soaks up impacts against docks and other vessels, and makes the boat almost impossible to sink. This pairing is why RIBs are the standard choice for rescue craft, military boarding boats, dive boats, and yacht tenders: they are fast, stable, hard to capsize, and forgiving in a seaway.

The boat is built from a hull and tube together with a propulsion and systems package. The Hull is the rigid deep-V bottom, and the Tube Assembly is the inflatable collar bonded around it. The Deck & Console gives the crew a working platform and helm, the Outboard Engine drives the boat, and the Steering System, Fuel System and Electrical System systems run it. The Deck Hardware covers mooring, anchoring and safety gear.

Hull

The Hull is what makes a RIB different from a soft inflatable. The Hull Shell is a laminated GRP deep-V, with around 20 to 24 degrees of deadrise at the transom so the sharp bottom slices into waves rather than slamming flat onto them. Inside, bonded Stringer stringers run fore and aft along a central Keel to stiffen the hull against the heavy pounding loads of running fast in a chop. A reinforced Transom carries the weight and thrust of the outboard, and Foam Fill foam packed into the hull cavities adds buoyancy and stiffness.

The deep-V shape is a deliberate trade. It needs more power to get onto the plane than a flatter hull, but once up it gives a soft, dry ride through waves and tracks straight at high speed. Combined with the buoyant tube above it, the hull also gives the boat enormous reserve stability: pushed hard in a turn or hit by a wave, the boat leans onto the tube rather than rolling over.

Tube assembly

The Tube Assembly is the inflatable collar that defines the boat's character. The Tube Fabric is a coated cloth, either Hypalon, a synthetic rubber that resists ultraviolet light and abrasion for decades, or PVC, which is cheaper and easier to weld but less durable. The tube is not a single bag: it is divided into several Air Chamber chambers, each sealed off and fed by its own Inflation Valve, so a puncture in one section deflates only that part and the boat stays afloat and usable. The seams are joined with Tube Seam Tape, the ends close in tapered Tube Cone cones at the stern, and a Rubbing Strake strip along the tube takes the wear of coming alongside docks.

The tube does three jobs at once. It adds reserve buoyancy high on the boat so the craft floats level even when swamped, it acts as a continuous fender that lets the boat lie against a ship or quay without damage, and it provides a wide, soft, grippy edge that crew sit on and that makes the boat hard to flip. For rescue work the low, soft tube also makes it easy to pull a person out of the water over the side.

Deck, console and outboard

The Deck & Console is the working area. A bonded Deck Sole forms a self-draining floor with Scupper drains that clear boarding seas and rain straight overboard. The moulded Console Shell houses the helm, instruments and steering, and crew ride on Jockey Seat straddle seats that absorb the shock of slamming through waves, holding onto stainless Grab Rail rails.

Propulsion is almost always an outboard. The Outboard Engine mounts on the transom on a Tilt Bracket with power trim and tilt so it can be lifted clear in the shallows. Its Powerhead is a four-stroke engine, with a cast Engine Block, Piston pistons, a Crankshaft, a Cylinder Head, a Flywheel carrying the alternator, and a Spark Plug per cylinder, all under a Engine Cowling. Drive runs down a Driveshaft through the Lower Unit, where a Helical Gear Pair and Propeller Shaft turn the Propeller, all supported on Ball Bearing bearings and sealed by an Oil Seal. A Water Pump draws seawater up to cool the engine.

Steering, systems and deck hardware

Steering uses a Steering System hydraulic helm: a Helm Pump behind the Steering Wheel pushes fluid through a Hydraulic Hose to a Steering Cylinder that swings the outboard, giving light, fingertip control even at speed. The Fuel System feeds the engine from an under-deck Fuel Tank through a Fuel Filter that separates out water, a Fuel Line and a Primer Bulb, with a Fuel Sender reading the level. The Electrical System system runs off a marine Battery through a Switch Panel and powers a Chartplotter Display chartplotter, a VHF Radio for safety traffic, and the Navigation Light.

The Deck Hardware is the working and safety kit. Cleat cleats secure dock and tow lines, a Bow Eye takes the trailer winch and tow load, and a Anchor on a Anchor Rode holds the boat at rest. A Lifeline runs around the tube as a continuous handhold, and a Bilge Pump clears any water that reaches the bilge. RIBs serve as lifeboats and rescue craft, naval and patrol boats, commercial dive and survey platforms, and tenders for larger yachts.