Hear from the experts about changing a cruising yacht to electric propulsion. Nestaway Boats proprietor, Ian Thomson converted his Sadler 29 to electric propulsion. Now he has the advantage of no noise, no vibration, diesel fumes or maintenance to worry about.
Inboard electric motor set up
The boat has been fitted with an ePropulsion 6kW POD drive with 18kW of lithium batteries. These replace the original Bukh DV 20 diesel engine. After a season of sailing Ian found the system gave good results.
“Electric motors are incredibly efficient and you don’t need as much power as a traditional HP engine. “
Here’s the results he monitored:
- 3.3 knots at 1kW output, 54-mile range
4.5 knots at 2kW output, 40-mile range
5/5.5 knots at 3kW output, 30-mile range
3kW equates to about 4.5HP, yet Ian could achieve 5 knots with 3kW. The torque is direct and instantaneous, which means it can turn a much larger propeller at a more efficient angle.
Ian feels that for cruising in the Solent and the occasional cross channel he has chosen the right power supply. He plans to use the motor as auxiliary power and does not intend to motor long distances against full spring tides.
Recharge the batteries using your sails!
The POD drive allows hydrogeneration to recharge the batteries under sail, and Ian says this normally puts in nearly as much charge as used to come in and out of Portsmouth Harbour. After sailing for a few hours it creates a net gain in battery charge.
In additional to solar panel and hydrogeneration, Ian recommends taking a 2kW petrol suitcase generator in a locker for a longer voyages. This would be enough to charge the batteries and get you home from mid Channel at around 4 knots.
Scalable battery power
The two eSeries 9kW batteries, weigh 87 kg each and take up a small amount of space where the engine used to sit. It is possible to add a further 50% battery capacity and still weigh less than the combined weight of the original engine and diesel tank. The additional power would add another 80-100 miles capacity. So if in future Ian decides to sail for much longer offshore voyages using an electric motor this would be an option.
Another advantage of changing a cruising yacht to electric is the additional storage space freed up by removing the engine and the diesel tank.
Ian is a keen sailor who owns Nestaway Boats and is a dealer for both ePropulsion and Torqeedo.
Discover more about changing a cruising yacht to electric propulsion in this Yachting Monthly feature.