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The Second Gamechanger for Electric Boats

Graham Balch
Posted by Graham Balch on Dec 7, 2020 8:41:39 AM

Oh my.

Twin electric motors is most definitely a game changer for the electric revolution on the water.

This blog explains why.

We at Green Yachts often think about what factors will accelerate the transition from boats with diesel and gas engines to electric. In our minds, there are four and we have in 2020, for the first time, checked off two of the four on the list.

We believe the four factors are:

  1. Hydroregeneration
  2. Twin electric motors
  3. Increased range from sustainable sources (better batteries, solar, hydrogen, etc)
  4. Boat redesign around electric propulsion

Oceanvolt has permanently changed the field of electric propulsion with its ServoProp, launched in 2020 after several years of testing prototypes. The boat with Oceanvolt’s first production ServoProp is the electric Arcona 435Z available from Green Yachts that is currently in Annapolis, Maryland.

Also in 2020, the first production monohulls with twin electric motors were produced. The first twin hybrid electric motor is a 2020 Arcona 465 delivered to a private buyer in the UK. Also, the first twin pure electric boat, the 2021 Salona S460 that has twin 10kW Oceanvolt Servoprops, is, at the writing of this blog post, going through the final stages of development and commissioning in Croatia before coming to the United States in early 2021.

Green Yachts got to sail this new S460 as we helped Salona with the development and commissioning.


Not only was the S460 a joy to sail as we cracked 10 knots of boat speed (while sailing in calm seas so that is not inflated by surfing), but the twin motors were incredible in three ways.

First, with two motors, the hydroregeneration doubles. This cuts in half the time it takes to regenerate energy while sailing. Instead of sailing 4-5 hours to regenerate an hour of motoring on a single motor, twin electric motors can regenerate an hour of motoring in 2-3 hours. It was fun to see each motor regenerating 400 to 1100 watts as we sailed around the beautiful islands of Croatia. And, since the two motors are outboard to the keel instead of centered behind it, the water stream past each motor is cleaner. We noticed better hydroregeneration on each Oceanvolt ServoProp motor than we have on a single Oceanvolt ServoProp centered behind the keel on other sailboats.

Second, the maneuvering in marinas is significantly easier. Twin electric motors will make the bow thruster the equivalent of the landline phone. I docked the Salona S460 in ~20 knots of wind. I wasn’t sure I could do it. In hindsight, I could have gone stern first down the slipway and used my momentum to back into the slip and maybe been okay. But I went bow first down the slipway and without the twin electric motors, I most certainly would have crashed into other boats as I went past the slip, stopped, reversed and turned my stern into the slip fighting a 20 knot wind on my beam.

Marin Donadini, the CEO of Salona Yachts who was on board, said, “If I had tried to do that maneuver in my sailboat that has a single engine, I would have crashed for sure.” And then, all of us on board talked about how bowthrusters fail after moderate use because they deplete the battery bank quickly and that a bowthruster would have failed in this situation and that twin electric motors was more reliable.

With twin electric motors, just like on a twin screw in a catamaran or a powerboat, you can use forward and reverse to steer. In fact, on a monohull sailboat, which pivots around the keel, the turning is better than any catamaran or powerboat I have ever maneuvered. By putting the port motor in reverse and the starboard motor in forward, one can pivot on a dime in a monohull with a keel. Diesel engines will never be able to be used in this way on a monohull sailboat. Never. Diesel engines are too big. Electric motors are small and can easily be placed under the aft cabin berths and this is why twin motors on a monohull sailboat are possible and such an advantage that they are a big nail in the coffin of the diesel engine on sailboats.

The third value of twin electric motors is redundancy. Electric motors don’t usually require more than 30 minutes of annual maintenance and they last so long (over 100,000 hours) that hours on the motor aren’t even tracked. Thus, it is unlikely you would need redundancy with an electric motor. But, every sailor knows how important redundancy of all boat systems are for safety and peace of mind so that if something breaks or gets damaged, you have a backup. With a twin electric motor, if one somehow got damaged or breaks, you have a backup. No sailboat with a diesel engine has an option for redundancy like this.


Topics: Electric Boats, Oceanvolt, Electric Propulsion

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