Can New Hydro-generators Serve Cruisers?

Can New Hydro-generators Serve Cruisers?

If the recent Velux 5 Oceans Race yielded one breakthrough, it would have to be the hydrogenerators from Watt & Sea. Racers Brad Van Liew and Zbigniew Gutkowski both used these devices. The sailors not only found themselves reliant upon the units, but were impressed by their capability and reliability as well.

Based in La Rochelle, France, Watt & Sea ( was founded by Yannick Besthaven, a former long-distance solo sailor who developed the product for his participation in the 2008 Vendee Globe race. Besthavens company currently manufactures two models: a carbon-fiber racing version that retails for $19,700 and an anodized aluminum cruising version that lists for $7,200 (a pair runs $12,455).

According to the makers specs, the cruising version begins generating power at just 3 knots of boatspeed. At 5 knots, the hydrogenerator reportedly produces enough juice to run all of the electronics (computer, instruments, autopilot, etc.) on a typical cruising boat. At 6 knots, the company claims, users can switch on water pressure and refrigeration. At 8 knots and above, the device reportedly generates 500 watts.

Gutkowski said his experience with Watt & Seas 17.6-pound cruising model was entirely positive. He noticed negligible drag from it and said: When the boat goes over 10 knots, that thing runs all of the electrical equipment on board: radar, navigation gear, electronics, and autopilots.

The racing version that Van Liew tested is even more efficient because its slightly lighter (14.6 pounds) and its variable-pitch propeller blades cause less drag. This model requires a minimum of 7 knots of boatspeed to begin generating power, and Watt & Seas literature claims that it will generate 500 watts at 12 knots.

The company claims that the cruising model will recharge a 200-amp, 12-volt battery to 50 percent of its capacity after 10 hours with a 5-knot boatspeed, and after only three hours at 8 knots. Van Liew experienced some overcharging problems with the prototypes he initially tested, but ultimately learned to extract the units from the water after his battery bank had been sufficiently charged. (The manufacturer said it has added a freewheeling feature to the system, which engages once the batteries are fully charged.)

Once Watt & Sea assembles the units, theyre pressurized with oil to prevent water seepage. The alternator is encased in resin, and ceramic-carbon gaskets are used between the main housing and the propeller unit. Each model is sold with a lifting bracket (intended to be mounted on the transom) and comes with a one-year warranty. The company also sells replacement props, converter units, and brackets.

Darrell Nicholson
Practical Sailor has been independently testing and reporting on sailboats and sailing gear for more than 50 years. Supported entirely by subscribers, Practical Sailor accepts no advertising. Its independent tests are carried out by experienced sailors and marine industry professionals dedicated to providing objective evaluation and reporting about boats, gear, and the skills required to cross oceans. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser who has been director of Belvoir Media Group's marine division since 2005. He holds a U.S. Coast Guard 100-ton Master license, has logged tens of thousands of miles in three oceans, and has skippered everything from pilot boats to day charter cats. His weekly blog Inside Practical Sailor offers an inside look at current research and gear tests at Practical Sailor, while his award-winning column,"Rhumb Lines," tracks boating trends and reflects upon the sailing life. He sails a Sparkman & Stephens-designed Yankee 30 out of St. Petersburg, Florida. You can reach him at