An new electric design from naval architects Robert Allan could be an ideal solution for the short, near-shore missions performed by pilot boats
Canada’s Robert Allan has developed a new all-electric pilot boat for short trips of 5 nautical miles (9.26 km) or less.
The RAlly 1600-E is an aluminium version of its steel predecessor, the RAlly 1600 class. The fully electric twin screw drivetrain is powered by an 815-kWh bank of batteries.
There are twin small auxiliary generators, usually not running, which provide range extension capability. The 16-m vessel’s top speed is 20 knots (37.04 km/h) and it can transport 2 crew and 4 passengers in total.
The boat can complete a full cycle of 5 nautical miles entirely on batteries, leaving 30% spare battery capacity. The propulsion motors are 500 kW 2,800 rpm permanent magnet 750 volt AC electric motors controlled by frequency converters providing a full range of speed. The motors drive through standard ZF or Twin Disc 3:1 reverse/reduction gears to conventional shafting and 840 mm propellers.
The battery system consists of 70 modules of Spear SMAR-11N-224 units providing a capacity of 815 kWh. These are arranged in a separate compartment located in the middle of the boat between the accommodation and the machinery space. The batteries are liquid cooled and the entire space is well ventilated and secured with a FirePro fire extinguishing system.
The same batteries also power the boat’s normal electrical demands. The recharging process is completed while docked, with power from shore. The entire design is eligible for Class approval such a Lloyd’s, ABS, or Bureau Veritas.
In some regions, various legislation on noise emissions means that accommodation areas must be far enough away from machinery to limit exposure to loud noise. In this case however, the two modules can be right next to each other because of the low noise and smooth running of the electric equipment.
The architects note that “the cost of the electric pilot boat is determined by construction location and the type of electrical system,” but say that the added capital cost of the electric propulsion system would be offset by eliminating fuel costs and reduced maintenance costs. The payback period is dependent on diesel and electricity costs and the number of operating hours per year.