Mustang delivers a line boat for Briggs Marine

Briggs Marine had Thorney Bay built to replace an existing boat at the Coryton Refinery in Essex UK, where the company has a long term ship handling contract to work the oil tankers of up to 250,000 dwt which arrive at the facility, located on the River Thames some 28 miles from central London.

Mustang Marine worked closely with Briggs Marine in designing the craft, which is derived from earlier line boat designs but updated following input from the local crews, which prefer to work lines over the bow rather than the stern. This has resulted in an aft wheelhouse configuration, providing excellent visibility onto the ample working deck forward.

The first line boat the Pembroke Dock based yard has built in many a year, Thorney Bay features a single chine hull form, with both hull and superstructure of robust steel construction. Scantlings are generally in accordance with the requirements of Lloyds Register Rules and Regulations for the Classification of Special Service Craft. The vessel complies with the Maritime and Coastguard Agency Small Commercial Vessel and Pilot Boat (SCV) Code and is certified to operate in Area category 3, up to 20 miles from safe haven.

Thorney Bay measures 9.95m LOA with a beam of 4.04m, a depth of 1.7m and a draft of 1.44m Displacing 18 tons with a full load, it is powered by twin in-line 6 cylinder Cummins QSB5.9-230 Heavy Duty rated marine diesels, each producing 230mhp at 2,600rpm and driving fixed pitch propellers through close coupled Twin Disc MG5061 reverse reduction gearboxes at 3:1. The direct injected, turbocharged and intercooled engines provide a bollard pull of 4.77 tons ahead, 2.7 tons astern, and deliver a 9 knot maximum speed.

The vessel is designed to have a minimum service life of 15 years, with the duty cycle typically involving an average of some 3,000 operational hours per year. Access for maintenance and servicing is of paramount importance for Briggs Marine and this was taken into account at all stages of the design and build process. An engine removal hatch is fitted at the top of the engine room casing, held in place with fasteners accessed from the engine room.

Crew safety is also important, with bulwarks and handrails fitted around the deck and raked inwards. A substantial tubular frame is fitted over the wheelhouse and bolted to the engine casing forward and the bulwark capping at the transom.

‘D’ section rubber side fendering of 150mm diameter is fitted to port and starboard deck edges over the length of the hull. Additional lengths of 100mm ‘D’ section rubber fender is fitted fitter vertically to the forward part of the bulwark both port and starboard. A robust steel push bow structure is fitted with two vertical lengths of 150mm ‘D’ section rubber fendering and a 150mm ‘D’ section rubber top capping.

At the bow, a single 168mm diameter heavy duty pipe is welded into the structure to act as the forward mooring bollard. A capping plate is fitted and a 30mm diameter pin welded through the tube at the top to form the stag horn. Mooring bits are fitted to the top of the bulwark, two forward and two aft. A heavy duty double bitt is fitted immediately forward of the engine casing. Panama fairleads are fitted into the bulwarks, two forward and two aft, and two heavy duty deck rings are fitted on the foredeck, one port and one starboard of the centreline. These rings are arranged flush with the decks. Four lifting lugs are also integrated into the vessel’s structure.

Access to the wheelhouse is via a half glazed sliding door in the aft bulkhead on the starboard side. Three windows and three overhead skylight windows provide good overall visibility and the front screen is fitted with a single Hepworth 50NM variable speed pantograph screen wiper on the port side.

Engine throttle and gearbox control is operated remotely by a Kobelt 2047 twin lever single station unit mounted on the helm console, where the engine manufacturer’s original instrumentation and control panels are also fitted.

Briggs Marine crews are reportedly happy with their new craft and the goodwill created between Briggs and Mustang Marine has led to the two companies working together on other projects. Mustang Marine is a Seawork 2010 exhibitor and an announcement may be forthcoming on Stand 85 at the show.