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Old 11-17-2002
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Electric Motors and Sailing Vessels


Charleston Boatworks' flagship Troika has been repowered with an electric motor and technology that may mean the future has finally arrived.
When it comes to onboard propulsion systems, there hasn’t been  much thinking-outside-the-box over the last century or so. Variously shaped pieces of steel or aluminum lubricated by oil interact rapidly and repeatedly to produce heat and a controlled explosion fueled by gas or diesel. Energy from this is transferred via the transmission and shaft to a propeller and the boat moves. However, on an abandoned Navy base just north of Charleston, SC, an alternative approach to propulsion for the future of boating is being tested. The size, shape, and capabilities of this new electric device are markedly quieter, cleaner, and more efficient than propulsion systems of the past.

I’d heard a little bit about electric engines. But having relied on our 350-pound trusty 1969 Volvo MD2B iron genny for close to two years on a cruise from San Francisco to Charleston, I admit to being among the naysayers when it came to the idea. Despite a long litany of mechanical misadventures—an oil change that had inadvertently shot out hot oil over sail bags in California, a blown head gasket in Mexico, and an extensive repair in Florida that involved my cradling the piston in my hands—when the wind dies, for me that's always meant turning to internal combustion engines (oars aside), simply because there hasn’t been too much of a choice.

As I pulled into the abandoned navy base in North Charleston that Charleston Boatworks now calls it home, a small fleet of derelict 40-foot Navy service vessels lay rafted up in a forgotten heap at one end of the yard as a gigantic crane on rails (actually the yard’s travel lift) stood watch. The illbruck Challenge's Volvo Ocean 60 made an impressive backdrop for a score of other cruising and racing boats undergoing various refits and bottom jobs. Nearby, Teddy Turner Jr.’s 40-foot Condor trimaran Troika sat moored next to a floating steam plant on a barge.


Yard manager John Spence inside the 40-foot trimaran was intimately involved with the electrical system now powering the boat.
Yard manager John Spence was on hand to show me around and give me a tour of Troika. The sleek, high-floating trimaran I now saw seemed to be an entirely different vessel than the abandoned orphan that had been in my marina a year or so earlier. The vessel had raced in the last Charleston to Bermuda Race. "They hit a whale on the way there," said Spence. "Basically, the few things on the boat that didn’t break on the way to Bermuda broke on the way back." The generator also caught on fire during that trip, so the need for reliable systems on the upcoming voyage was well understood.

The trimaran had been essentially disassembled into five pieces, rebuilt, reassembled, painted, and now stood ready for her first voyage. "It was an expensive way to get a new boat, although in the end it was actually cheaper than buying new," said Ted Turner Jr. of the refitted vessel that is now the flagship of his new boatyard. Originally designed for transatlantic races, Troika is 14 years old, and the major work done to her—reinforced floats and bulkheads, new sails, and power plant—are likely to see her through plenty of sailing seasons to come.


All of 98 pounds, the Electric Wheel generates more torque than diesel engines. A six-horsepower electric motor can replace a 20 to 30-horsepower diesel engine. As an added bonus, allowing the prop to spin underway generates electricity.
The Electric Wheel—Troika's new power plant—is a 20-hp motor made by Solomon Technologies that can move the boat at five-and-a-half knots, Spence explained, although the team thinks it will be able to get to six knots once they find the right prop pitch. Ten Lifeline Group 20 batteries are connected in sequence to achieve 120 volts. The 120 volts are then run through a converter to step the electricity down to 12 volts in order to run the ship's power, which includes a 12-volt cold plate, a microwave, lights, autopilot, and instruments. The biggest power draw had formerly been the SSB HF radio, but this has been replaced with a satellite phone, which when connected to a laptop, allows e-mail capabilities while underway.

So what powers the batteries, you ask? A variety of things can serve to keep the batteries up to charge. On cruising boats, solar panels and a wind generator can contribute to keeping the motor running if need be. On Troika, a performance-oriented trimaran, a Panda 4KW generator ensures that the voltage never falls below a critical level. The generator uses a quart of diesel an hour, and automatically kicks should the voltage fall below 11.4 and shuts off after charging. The generator also has its own starting battery.


For yard and boat owner Ted Turner Jr., the system is a big improvement over the two outboards that formerly powered his craft.
Turner reckons that the system is a vast improvement over the boat's previous means of propulsion—two Honda four-stroke 9.9-horsepower outboards on brackets. The gas engines meant two different fuels had to be used on board, diesel and gas, and the extra weight of two 12-gallon tanks, fuel lines, fittings, and brackets, to say nothing of the dousing the engines received mounted on the cross beams. The generator also has an automatic shut off, meaning that if it senses there’s a problem with oil, fuel, or water, it will shut down.

"In theory, you can keep the boat at the dock and it should take care of itself," said Spence. Additionally, since the configuration of the batteries means there is no need for a shorepower plug, you can just plug it into a 110 volts. "We think if we were motoring for 24 hours, the generator would run for about half that time."


And although the diesel generator is an integral part of the system on Troika, its quart an hour burn rate means a long cruising range for the trimaran.
The engine itself weighs a mere 98 pounds. One of the advantages of the system, especially for racing boats and performance orientated cruisers, is that the weight of the batteries can be placed wherever the ballast is best served, over the keel, say, and not necessarily aft near the engine. But the engine also has something conventional arrangements lack—self generative energy. When sailing, the prop can be allowed to spin, causing the engine to turn, producing energy, and which can recharge the batteries. While the amount of energy this produces depends on conditions, one reviewer of the Electric Wheel found three hours of sailing time recharged one hour of motoring.

Even when motorsailing, the system can discern the difference between motoring up a wave and surfing down it, and transfer energy to the battery banks. The engine is also more efficient when it comes to horsepower ratings. Inboard combustion engines usually have all sorts of horsepower-robbing pumps, compressors, and alternators connected to the fly wheel by belts. The Electric Wheel side-steps these parasites, and with less energy lost via these and the transmission, the torque is directed where you want it, at the propeller. A 98-lb six-horsepower motor can replace a 20-to-30 horsepower motor, and a 10-horsepower electric model can replace a 30-to-40 horsepower engine.

"When it’s on you hear things you’ve never heard before," said Spence, who’s company is looking forward to installing more of these units in the future, "like the shaft in the cutless bearing, and the prop spinning, which is ordinarily drowned out by the engine." And with no transmission, one can shift from full forward to full reverse without a pause.

The Electrical Wheel is available to fit the engine mounts of several types of engines. But it’s not something the average person would be able to drop in themselves. There’s a lot more circuitry, according to Spence, and alignment concerns remain the same, although vibration is more of a whirring nature and less of a chunk-chunking. You’re not likely to be able to take it apart and repair it, if some kind of glitch in its 80,000 to 100,000 maintenance-free design life does crop up while you’re marooned on a South Pacific island. So how much for one of these gizmos? Spence estimates about $5,000 in labor, $9,200 for the generator, $8,000 for the electric motor. And while those numbers might initially seem daunting, you could expect to drop something in that neighborhood for a diesel engine and generator if you were repowering your boat, and still have exhaust fumes, noise, and a fossil fuel mentality.

Going to the Source

The Electric Wheel was first patented in 1991 by Solomon Technologies, and the Benedict, MD-based company has gone on to work with NASA in getting the Mars Rover Sojourner rolling across that planet’s forbidding terrain and in its inhospitable conditions on its mission in 1997. If the technology is good enough for martians, it may just be good enough for you too.

The manufacturer of the Electric Wheel claims a lifespan three times greater than that of the average diesel engine. Twenty-three electric wheels are currently (no pun intended) whirring along in mono and multihulls ranging from 24 feet to 50 feet. Optimum performance of the Electric Wheel is achieved with a 144-volt system, typically fueled by twelve 12-volt batteries. Currently Group 27, 31 or 4D batteries are being used. The life cycle of batteries is dependent on their use, and when properly maintained, the life cycles of the batteries exceeding five years can be achieved, according to the company’s website. The average installation takes about five days, not including a day or two to remove the old engine and spruce up the engine room, and silent power is warranted for five years. For more information see www.solomontechnologies.com.




Suggested Reading:

Electrical Work Rules by Don Casey

A Little Help from the Sun by Don Casey

Choosing and Installing Solar Panels by Sue and Larry

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