The Port of London Authority (PLA) has nominated a hybrid power system for a newly ordered pilot boat. Described as a parallel hybrid craft, combining both diesel and electric power, the 14m x 4.8m cutter is intended to be completely emission-free when operating in electric mode.
Contracted domestically from Norfolk boatbuilder Goodchild Marine, the craft will be the first of its kind in the UK ports industry, and will be based on the ORC 136 design developed by French naval architecture consultancy Pantocarene. The order ties in with the PLA's current air quality initiative for the tidal Thames, the first such scheme in the UK, which has been launched as a five-year action plan, aimed at reducing harmful marine emissions along the tideway while facilitating the growth of the port and the capital.
Designated the ORC 136.HY type, the new hybrid vessel is due for delivery in spring 2019 and will supersede the PLA's1982-built, 16.4m-long Patrol. The ORC hull, characterised by a beak-like bow form designed to enhance all-weather capability, typically uses 40% less diesel fuel per nautical mile (nm) than a conventional hull, such as that of Patrol. Fuel consumption is further reduced as the ORC is only half the weight.
The duty cycle of a service craft such as a pilot cutter, with its widely varying operating profile, is a fundamental determinant of the propulsion arrangements, taking into account factors including range, cruising speed, idling speed, time alongside and time between deployments. The new craft is expected to make up to 15knots on hybrid power and will be used by the PLA for pilot transfers on the lower tideway in Gravesend Reach.
Twin Yanmar 6LY400 diesels, which have an output of 294kW at 3,300rpm at the standard, maximum rating, will be customised and supplied by UK firm E.P.Barrus, while the Italian-produced Transfluid plug-and-play electric/hybrid system will be delivered by Kent-based driveline specialist Marine & Industrial Transmissions (MIT). The battery system will ensure a minimum 50% charge level in just 30 minutes and complete recharge in two hours. The pack is DNV GL-approved and is rated for more than 3,000 cycles.
The batteries will be charged from the shoreside grid when the boat is at her regular berth alongside Royal Terrace Pier in Gravesend, or from the engines when under way in diesel propulsion mode.The craft will run on batteries for approximately 40nm on a single charge, at speeds up to 15knots. The diesels will provide boost power, taking top speed to 19knots, and will ensure back-up to electric propulsion for longer duty cycles.
PLA chief executive Robin Mortimer has commented: “We expect that through the power train, hull design and lower weight, the hybrid cutter will use less than 10% of the fuel used by our current vessel, with carbon dioxide emissions similarly reduced. That should see us going from using 86,000litres of fuel for our pilot cutter operations a year to around 7,000 litres.”
For the skipper in the wheelhouse, shifting between electric mode and diesel mode is accomplished simply by pressing a button with the lever in any position. Booster and regeneration modes are activated by a side button on the control lever. The cutter will have the capacity for two crewmen and three pilot passengers.