Tugboat designer Robert Allan has created an all-electric pilot vessel design for zero-emission transfers in ports. Its RAlly 1600-E design is an aluminium version of a steel predecessor with a range of 5 nautical miles.
It has a fully electric twin-screw drivetrain and a bank of high energy-density batteries that would be recharged from shore power, as well as two small auxiliary generators for times when the pilot vessel has sailed beyond the range of its batteries and needs to return to a charging point.
RAlly 1600-E has been designed with a top speed of 20 knots. Robert Allan said a fully electric propulsion has “significantly reduced” operating costs and could complete a typical pilot transfer with 30% of nominal battery capacity to spare.
With an aluminium hull, this 16 m vessel has a similar weight to a steel diesel-electric pilot vessel as the weight saved from the hull and removal of diesel engines and fuel compensates for the mass of the electric drive and batteries.
It has been designed with two 500 kW propulsion motors with permanent magnets and 750 V AC electric motors controlled by frequency convertors.
These motors drive through standard ZF or Twin Disc 3:1 reverse/reduction gears to conventional shafting and 840 mm propellers.
Battery systems consist of 70 modules of Spear SMAR-11N-224 units providing a capacity of 815 kWh. These are arranged in a separate compartment which is located in the middle of the vessel between the accommodation and the machinery space.
These batteries are liquid cooled and the entire space is air ventilated and fitted with a FirePro fire extinguishing system. The batteries also power the boat’s normal electrical load of lighting and auxiliaries. The entire design is eligible for class approval from with Lloyd’s Register, ABS, or Bureau Veritas for example.