Electric Yachts – The Future is Here
Imagine being able to cruise the far corners of the Earth without ever having to search for a cylinder of cooking gas, or a refill of diesel. Nowadays, this is quite feasible, because your galley and powerful main engine can be entirely electric, and the modern lithium-ion battery bank can be quickly recharged by a combination of solar panels, wind generators, and a freewheeling propeller under sail.
We’ve always had yachts capable of generating their own electricity from renewables, of course, and as the domestic appliances on board have multiplied, so have the demands for off-grid energy. But the ultimate goal of reliably replacing the diesel engine with an equivalent electric motor has so far proved elusive. Although a yacht requires very little horsepower to achieve hull speed in calm conditions, it will still need about 3hp per ton when bashing into a heavy sea. Many yachtsmen also prefer to have plenty of grunt in reserve, so a modern 40ft (12m) yacht will usually pack anywhere between 55hp and 80hp (72–104kW).
Feeding a relatively meaty (10kW/13hp+) electric motor for any length of time requires a large bank of batteries, and high loads can quickly drain them. To date, the problem with dedicated electric propulsion has been one of range, so a practical compromise has been reached with a hybrid installation. A small-to-medium-sized combustion engine takes over the propulsion duty in periods of high demand, or when the batteries are depleted. The engine also spins the electric motor as a generator. Once the batteries are topped off, the electrics are once again available for silent running. Because of the need for an additional ‘range extender’, electric propulsion has usually been an add-on for a cruising yacht, and not the sole provider.