An important decision you have to make when you get an electric sailboat is whether you get a pure electric boat or hybrid electric that has a DC marine generator on board.
In a pure electric sailboat, Green Yachts typically recommends a 30kW battery bank. This gives a boat a 30 to 80 nautical mile range depending on your boat speed, boat displacement and length of your waterline. When you add solar onboard and use an Oceanvolt electric propulsion system that allows you to hydroregenerate energy back into the battery, you should have all the range you need if you primarily sail.
In a typical sunny day, if one motors in the morning at 5 knots from 0800 to 1200 when there isn’t much wind and sails from 1200 to 1700 at 8 knots, a speed that Arcona and Salona sailboats are more than capable of doing, a sailboat with a 1200 watt solar system and a 30kW battery bank would use ~14kW of power motoring in the morning and generate (at 75% efficiency given shading/morning light), 3.6kW of energy back into the battery bank for a net negative of 10.4kW. In the afternoon, the solar provides 4.5kW of energy and hydroregeneration provides 5kW. If you start the day with 30kW in your battery bank, at the end of the day, you have 29.1kW. That means you could do 30 days in a row like this and not deplete your battery bank. If you take any day off or sail more, it means you are completely energy independent. As long as your are sailing more than motoring, you have all the power you need even in weeks of cloudy weather.
However, many sailors depend on their engine as a primary means of getting somewhere, which leads us to looking at how a diesel engine compares to a hybrid electric system. If a sailor wants to go 300 nautical miles in light wind and doesn’t want to sail as slow as the wind will take them, then the best option is to turn on the engine to get from point A to point B faster. Most sailboats can motor 300 or more nautical miles with a diesel engine whereas with pure electric, this is not possible.
But, this is where a hybrid system significantly outperforms a diesel engine and makes buying a new boat with a diesel engine not as good an option.
Take a Beneteau 41.1 with a 53 gallon fuel tank and a 45 HP Yanmar engine vs a Salona S41 with an Oceanvolt 10kW Servoprop system, an 11kW marine diesel generator and a 25 gallon fuel tank for the generator. The Beneteau 41.1 can go about 400 nautical miles at 5 knots on one fuel tank. The Salona S41 can go 575 miles motoring at 5 knots with half the fuel! This is based on the marine generator burning ½ a gallon of fuel per hour and creating 11 kW of energy, the Oceanvolt motor using 5.5kW to go 5 knots per hour and starting with 22kW in your battery bank. That means a hybrid electric sailboat has 43% more range motoring with half the fuel compared to a traditional boat with a diesel engine!
When you go pure electric, you have less range than a diesel engine, but less maintenance and less noise. When you go hybrid electric, you have more range than a diesel engine, but similar maintenance and noise to a diesel engine.
In the end, there is no right or wrong answer about going pure electric or hybrid electric. It really depends on your needs and how you sail. The good news is that regardless of what style of sailing you enjoy, an electric system is superior to a diesel engine. This is why Sail Magazine said in 2018 that the future of sailing is electric. Green Yachts can help you design your electric system to best fit your needs and we look forward to talking with you about it!
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