The wheelhouse equipped RIBs can carry up to 12 passengers each at speeds near 30 knots and are successfully deployed for some 2,000 hours per year by each of their operators.

The three boats, all built by Mustang Marine under their wholly owned subsidiary, Ocean Dynamics International Ltd RIBworker© brand. The RIBworker© design has in recent years seen additional models added with the range now extending to four hull types with hull lengths up to 15m. Expanding the vessel type range further Mustang now has cooperation agreements with vessel designer Camarc for pilot boats and Australian design house Incat Crowther for workboats and ferries.

Having already observed the effectiveness of the RIBworkers in local conditions, Captain Covell’s decision to purchase a similar D Class sparked the decision to re-appraise the design especially as the vessel had to comply with the Pilot Boat requirements under the workboat code. Subtle changes to the hull and a redesign of the wheelhouse ensured the code requirements could be meet. The hull structure is now fully compliant with Lloyds Special Service Craft rules. Additional space in the engine bay ensures ease of maintenance without compromising passenger comfort.

The RIBworker D Class is an 11.5m aluminium hull RIB with a single marine diesel driving a waterjet, but equipped and coded to also perform in the pilot boat role when the larger vessels, usually small cruise ships, call at the islands.

The new boat, ‘Pegasus’, was delivered last month and replaces a Nelson 44, which the customer, the Duchy of Cornwall, had purchased some years ago from Harwich Haven Authority. Apart from the requirements for pilot duties, the biggest differences from the earlier Scillies RIBworkers are the choice of a Caterpillar C9 ACERT engine, a redesigned wheelhouse giving greater width for the side decks to meet MCA pilotage regulations, a redesigned console arrangement with radar and plotter screens and the first time a wet exhaust silencer unit by Manuflex was used, greatly reducing airborne sound levels. As water taxi duties are not this vessel’s primary purpose, there is a different seating arrangement, with positions for cox, crewman and six passengers internally and a removable seating module which mounts atop the aft deck engine cover providing six external seats when required.

Pegasus has been built in compliance with the MCA Workboat Code category 3 with a Pilot Boat endorsement. Featuring a hard chine deep ‘V’ hull in marine grade 5803 aluminium, the vessel displaces 6.7 tons fully loaded, has a beam overall of 3.81m, a laden draft of 0.65m and will run light at 29 knots.

The hull is divided into three longitudinal compartments for excellent longitudinal stiffness and structural continuity. Further subdivision gives seven watertight compartments allowing large safety margins in the event of damage. A push bow complete with a unique compressor deck is fitted as an additional restraint on the inflatable collar at the bow when hitting the heavy weather common around the Scillies. An under-deck store is provided aft of the collision bulkhead and the fuel tank is located amidships under the main wheelhouse sole. A capacity of .55m3 provides for five hours running at cruising power with a 10% margin.

The inflatable collar is 1850 Dernier Tex heavy duty Hypalon coated Neoprene with a protective fender bonded to the outside at three levels along the length. At the bow a single heavy duty pipe is welded into the structure to act as the forward mooring bollard, with a capping plate and pin welded through the tube at the top to form the stag horn. At the stern platform, a single mooring post is fitted port and starboard. Two single post mooring platforms are fitted amidships port and starboard, arranged integral with the vessel’s structure.

The Hamilton HJ322 waterjet unit is bolted to the cast mounting plate which is integrated and welded into the ship’s structure and hull. A bolted flanged sealing ring is fitted in the transom to prevent the entry of water. A transom mounted stern platform is fabricated and welded in place to provide a convenient boarding platform and protection for the jet unit. A Volvo ‘QL Boat System’ trim control is fitted, comprising two 450mm electronically actuated interceptor plates at the transom, with a control panel fitted at the helm station, including a position indictor.

The propulsion system is arranged with the engine mounted in the engine compartment in such a way that it can be removed and replaced through the engine hatchway.

The in line, six cylinder, Caterpillar C9 ACERT produces 503bhp at 2,500rpm. A hydraulic reversing gearbox fitted close coupled to the engine provides the necessary reduction ratio to optimise jet performance and also acts as a clutch mechanism, with an option to reverse the jet impellor for back flushing.

Kobelt engine control levers are fitted to the wheelhouse console, along with a digital engine monitoring panel and start/stop key and switch.

Power is transmitted to the Hamilton waterjet unit via a constant velocity Carden shaft arrangement, fitted between the gearbox output and jet unit input half couplings. The jet intake is fitted with a weed rake for cleaning whilst afloat, with the rake operated by a foot pedal attached to the side of the jet intake. The reversing bucket is hydraulically controlled and activated by a lever at the helm position. A combined hydraulic pump/reservoir is belt driven from the jet half coupling, with a follow up control valve and cooling ducts built into the jet casing.

Steering is by means of a hydraulic ram attached to the vector nozzle link arm at the jets.

The wheelhouse is naturally ventilated by a low profile Vetus UFO unit and heated by a Webasto Airtop 2000 system. Toughened safety glass windows give good all round vision out of the wheelhouse whilst an aluminium access door at the rear has its own window and runs on nylon slides. The coxswain and crewman enjoy KAB 301 suspension seats complete with armrests whilst wheelhouse passengers ride on  KAB 11T1 models fitted on aluminium plinths with footrests and lifejacket storage below.

The NavComms package includes twin Icom IC603 VHF GMDS compliant radios. A Raymarine Pathfinder Smart Heading Sensor gyro stabilised compass system is designed for use with Pathfinder Plus range of radars and chart plotters, in this instance a compact 18” high performance Pathfinder which interfaces with two E120 multi-function navigation displays and also integrates an Echo Pilot FLS fish finder.

Underwater parts of the hull have cathodic zinc anode protection whilst the hull’s wetted surfaces are coated with anti-foul paint. The decks are uncoated and left with a rough blast non-slip finish. The external superstructure is coated in a marine epoxy paint system finished in the bright colours of the Duchy of Cornwall.

Photos L - R

1) A bare bones shot of ‘Pegasus’ reveals impressive structure early in the build. Photo by Jack Gaston.

2) Mustang Marine MD Kevin Lewis hands the craft over to St Mary’s Harbour Master Captain Glen Covell, with the vessel’s cox looking on.

3) Impressive performance and handling during trials.

4) All controls and screens are well placed at the helm.

5) The Caterpillar C9 ACERT is mounted so as to expedite easy removal.