Dover Gets a New Pilot and Patrol Vessel
On the 11th of October the Dover Harbour Board formally introduced and christened their new pilot and harbour patrol launch. The vessel was named 'Dovorian' by the wife of Dover Harbour Board's current chairman, Mrs Dibble, at a short ceremony in the port.
Both roles are demanding. With 135 cruise vessels scheduled to use the port in 2007 and cargo ships using the harbour, pilots are often transported to meet ships 3 to 5 miles outside the port in almost all weather conditions. The extremely busy port, with its virtually continuous succession of ferry movement, places a heavy responsibility on the harbour patrol launches to monitor traffic movements and keep other users safe, particularly during the summer months.
With those demanding roles in mind an exacting specification was drawn up for a vessel meeting all of the required criteria for seakeeping, manoeuvrability, durability, performance and reliability. The design chosen from among many on offer was the new Aquastar Nelson 42, incorporating a moulded chine beneath the waterline, proving greater dynamic stability and a drier ride. A well rounded and balanced transom is an important feature when alongside and manoeuvring away from moving ships. An added benefit is a reduction in fuel consumption, quoted as 'up to 20 percent' using the new hull design.
The task of designing and constructing the new vessel was entrusted to Goodchild Marine Services Ltd of Burgh Castle, near Great Yarmouth. With over 25 years of experience in building workboats, lifeboats and pilot vessels behind them, the company offers a wide range of design and construction services and has a close working relationship with Aquastar Limited in Guernsey. The final design is based on the well proven Aqua Star 42 Nelson hull, known for its exceptional seakeeping qualities and good handling characteristics, was mated with a wheelhouse and accommodation custom designed and built by Goodchild to meet the owner's exact requirements.
Dovorian is a twin screw launch of 12.80m in length, with a moulded beam of 3.98m, a draft of 1.08m and displacement (approximate) of 13 tons. Some 1,300 litres of fuel and 30 litres of fresh water can be accommodated. Provision is made for a maximum complement of seven persons. The hull and superstructure is moulded in accordance with Lloyds Register of Shipping SSC rules appropriate to Pilot Vessels and complies with the requirements of the MCA Harmonized Workboat Code of Practice for Pilot Vessels - category 3.
The Glass Reinforced Plastic (GRP) hull is a one piece moulding manufactured by Aquastar Guernsey at their own yard and delivered to Godchild as a complete hull, incorporating girders, stringers, transverse frames and bulkheads. A one piece GRP deck moulding manufactured on the premises by Goodchild is bonded to the hull with mechanical fastenings, adhesive and over-bonding. The bilges are finished in gel coat and the machinery compartment and exposed internal surface coated with a fire retardent. Wheelhouse and superstructure were also produced on site and constructed as a balsa cored, one piece moulding bonded to the main deck. The forward coach style roof has a bolted, removable section to enable the engines to be removed.
Internal space is divided into five compartments; the forepeak and forward accommodation (used for stowage and as a watertight void space), the machinery compartment, wheelhouse and after-peak, all of which have watertight doors or hatches. All hatches, doors and windows were selected from the 'Seaglaze' range. The wheelhouse features seating for the helmsman to port and crewman to starboard, and in all five KAB 301K adjustable suspension seats with armrests and lap belts. All seats are mounted on base units, forming stowage lockers. An additional bench seat on the portside is also provided with lap belts.
Dovorian is powered by two Scania D19 46M main engines rated 352 bhp (259kW) at 2,200 rpm. Power is transmitted to a pair of heavy duty propellers via Twin Disc MGX 5114A close coupled, down angle, 'Quickshift' gearboxes with a 2.04:1 ratio. Clements Engineering has supplied stern gear and propellers for Goodchild boats for many years and do so again for Dovorian.
The gearboxes are controlled through a Twin Disc TDEC-400 electronic control system incorporating the latest full authority micro-processor technology, now available for Twin Disc transmission systems. The shift system integrates the gearbox controls and engine throttles,
allowing faster shifts, rapid acceleration and precise control of vessel speeds. Three 'selectable' modes of operation are available; Cruise, Express, and Troll and a synchronising facility. The system offers the operator a 'soft clutch take-up' while manoeuvring, and modes of operation ideal for the main roles undertaken by the launch, including pilotage duties, harbour patrol and survey work.
The vessel is fitted with twin rudders controlled by hydraulic steering gear incorporating a diverter valve for emergency changeover to manual operation if required.
'Wet' engine exhaust systems comprise Halyard silencer /mixer boxes, reinforced marine grade exhaust hose and GRP connectors. The system is designed to prevent 'back-flushing' and expel the exhaust emissions well clear of the transom. HMI temperature sensors are incorporated with visual and audible alarms located at the control position.
Two fuel tanks, each with a capacity of 140 gallons (650 litres approx), are of stainless steel construction and located beneath the wheelhouse.
Dovorian's hull was treated after completion with Seajet 033 Shogun anti-fouling, supplied by UK distributor Marine and Industrial Ltd. 033 Shogun is an advanced self-polishing anti-foul that relies upon a sophisticated method of biocide release to create a chemical reaction with the water immediately upon immersion, but does not leave a residual crust to inhibit further biocide release.
The vessel's 24 volt DC electrical system is based on two banks of batteries, each with a capacity of 200 amp/hours. One bank is exclusively for engine starting and the other for services and equipment. An alternator on the port engine charges the starting batteries and a twin-alternator arrangement on the starboard engine serves the second battery bank. Power for navigational equipment, radios and other equipment requiring a 12 volt supply are fed via a converter.
Two bilge pumps are provided, both connected to a central bilge manifold system. One pump is a manual 'Henderson' double diaphragm pump, with a minimum rating of 70 litres/minute and the other an engine driven JABSCO 1.25 inch pump. The latter is fitted with a vacuum switch and operated by an electro-magnetic clutch operated by a switch in the wheelhouse.
Dovorian is a well appointed launch, fitted out to a high standard. A portside helmsman position was chosen and the controls fall easily to hand. In addition to the engine and gearbox controls and instrumentation the boat is equipped with a Simrad CA44CRT radar with a 10inch display and Simrad GPS. The magnetic compass is a Plastimo Offshore 135 instrument and Raymarine supplied an ST 60 speed log and depth sounder. Radio communication is provided by an Icom IC-M601 DSC waterproof VHF set and an ICOM IC-M1 Euro V waterproof handset.
Also fitted is a Sea Marshal 'man overboard' location system designed to work in conjunction with transponders carried within the pilots' clothing. On deck, the statutory handrails and 'Hadrian' safety line attachments are provided for pilotage duties and a recovery platform and boarding ladder is installed in a moulded recess in the transom. A stainless steel 'swing-out' gantry is installed aft, complete with a floodlight for night use.
Dovorian has been well accepted by the crews who readily confirm the excellent performance and handling of the new launch. The vessel it has replaced will now be sold and Dovorian will work alongside the Director, a vessel built to an earlier Aquatar design and one that continues to give excellent service.
By JACK GASTON
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