Rigid Inflatable Rescue Boat

Overview

A rigid inflatable boat combines two older designs: the planing performance of a hard-chine fiberglass hull and the buoyancy, fendering, and low freeboard of an inflatable. The Rigid Hull gives the boat its speed and seakeeping; the Inflatable Collar makes it nearly unsinkable, forgiving alongside other vessels, and easy to pull a casualty over. This combination made the RIB the default craft for lifeboat institutions, coast guards, harbor patrols, and ship-carried fast rescue boats under SOLAS.

The configuration described here is a 6.5 m single-outboard boat with a center Helm Console, the size class typical of lifeguard units and pilot/patrol tenders: small enough to trailer and davit-launch, large enough to work offshore in moderate sea states.

Hull and collar

The Hull Shell is a hand-laid GRP molding with a deep-V section, about 24° of deadrise at the transom, that slices waves rather than slamming over them. A bonded Stringer Grid of foam-cored stiffeners carries slamming loads of several g into the laminate. The Deck Panel above it is self-draining: shipped water runs aft and out through the Drain Plug fittings rather than pooling. A polyurethane Keel Guard takes the abrasion of beach landings.

The collar is a 47 cm tube glued to a flange at the sheerline. Its Tube Skin is polyester cloth coated with chlorosulfonated polyethylene, chosen over PVC for UV, fuel, and abrasion resistance in professional service. Four conical Chamber Baffle diaphragms divide it into five chambers, each with its own Inflation Valve and a Pressure Relief Valve that vents above the 0.24 bar working pressure when the sun heats the tube. A single puncture costs one-fifth of the collar; the boat remains operable. The Rubbing Strake along the tube centerline absorbs contact when coming alongside a casualty vessel, the collar is the fender.

Propulsion and steering

Power is a single outboard of up to 115 hp on the Outboard Interface. The Transom Plate is plywood-cored GRP, through-bolted via the Motor Bracket with backing plates. Two Control Cable runs carry throttle and shift from the console's Throttle Binnacle.

Steering is hydraulic: turning the Helm Wheel strokes the Helm Pump, which displaces fluid through Hydraulic Hose lines to the Steering Cylinder on the engine, linked by a Tie Bar. Hydraulics eliminate propeller-torque feedback at the wheel, which matters when holding station next to a person in the water at low speed in surf.

Rescue equipment

The Rescue Fittings are what distinguish a rescue RIB from a leisure one. A Lifeline loops along the outside of the tube for survivors to grab; six Grab Handle points secure the crew during high-speed turns. Casualty recovery over the low tube is assisted by the fold-down Rescue Ladder. A Towing Post aft is rated for towing disabled craft, and the Bow Eye serves davit lifting and trailer winching. SOLAS fast rescue boat variants add a righting bag on an A-frame so the crew can re-invert the boat after a capsize, plus certified lifting slings for launch and recovery from a ship underway at up to 5 knots.

Systems

The Electrical System system is a conventional 12 V DC installation: an AGM 12 V Battery charged by the engine alternator feeds a Fuse Block, with a tinned Wire Bundle serving the Navigation Light set, the float-switched Bilge Pump, and the console Switch Panel. The VHF Radio, a 25 W DSC set, is the working link to coordination centers and other SAR units.

Fuel lives in a 100 L welded-aluminum Fuel Tank foamed in under the console, feeding the engine through an A1 fire-rated Fuel Line, a Primer Bulb, and a 10 µm water-separating Fuel Filter, water in gasoline being the most common cause of engine failure exactly when the boat is needed. The crew rides Seat Assembly jockey seats astride the console, which protect the spine when the hull launches off waves at speed.