Boating Innovations | Engines Going Green


Electric and Hybrid Boats

By John Adey
Published: April/May 2012

The electric/hybrid boat market is heating up with new models as well as repower options. Should your next boat be a hybrid?

The phrases are familiar now, and promising: "green, smaller carbon footprint, hybrid," and so on. We've seen the growing success of hybrids in the automotive market, and we're starting to see the same trend when it comes to boats. So what are the things a potential buyer should know? Could a hybrid fit the way you boat?

Photo of a Greenline Hybrid
The Greenline Hybrid is equipped with both a VW diesel and electric motor, so it can run silently up to 6 knots, or up to 15 knots on diesel power.

The concept of hybrids at sea isn't new. WWI submarines used a diesel engine by night to charge batteries for electric propulsion underwater by day. Hybrid means anything that supplements a traditional combustion engine, be it gasoline or diesel. The supplement can be done in one of two ways: Parallel or Serial. Let's look at the distinctions:

Serial Hybrid — The prime mover is an electric motor supplied by a substantial battery bank of any type. A generator is optimized purely to charge the battery bank. The generator control can be automatic; starting and operating based on need without the captain's intervention, or manual where the captain decides when he or she would like to begin the charge cycle. These installations typically also include provisions for charging with shore power, solar, or wind.

Parallel Hybrid — The prime mover can be a combustion engine or an electric motor. Both drive the same prop shaft(s). Generally the installation will look like a traditional combustion engine but include an electric motor component between the engine and transmission. The key to this technology is the clutch system. You may be able to shift on the fly, seamlessly changing from combustion to electric with the touch of a button; though some require the engine to come to a complete stop before switching to electric. Charging batteries is carried out by the engine through advanced controllers and in some installations is supplemented by large solar panels.

This option lends itself to planing boats that need power to get out of the hole but can switch to electric while on plane. It's also a popular option in five- to seven-knot boats. These units are also being marketed as direct replacement refits, with additional battery power, of course!

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Unlike Cars…

…where the Hybrid version can cost up to 50% more than the base model, upgrading to an electric motor on a Hunter 36 only adds around 2% to the cost of the boat.

Hybrid Resources:

Greenline Hybrid boats:
Hunter Sailboats:
Mastervolt: batteries, hybrid systems, more;
Frauscher boats: hybrid and electric runabouts
and tenders;
Elco electric motors:
The Electric Propeller Company: hybrid and electric retrofits.


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