Towed Water Generators: Are They Worth It?
Posted by Darrell Nicholson at 04:56PM - Comments: (7)
July 14, 2013
The fact that two out of 10 cruising boats I saw docked here in Bergen, Norway, have towed water generators made me wonder whether the Scandinavians have had better luck with these devices than we have. My guess is that the units I saw on the sterns of two Swedish boats have had very little use over their lifetime. Most owners of towed water generators that I have spoken with, even those who take long passages when the generators would seem most useful, seem unenthusiastic about the devices.
It has been a long time since Practical Sailor tested towed water generators, and the number of choices remains extremely limited. (As I mentioned in the July 2013 editorial, the ocean cruising sailor is a small and fickle market.) The last towed water generator we reviewed was the Hamilton-Ferris towed water generator.
The units I saw in Bergen looked like they were the Aquair 100 made by the British manufacturer Ampair. In our article on Choosing a Wind Generator, we mention Ampair, and we describe its wind generator in greater detail our marine wind generator test (available only to subscribers). We have not yet had a chance to test the Aquair 100, but it operates in a similar way to the Hamilton Ferris unit. Both tow a small impeller that looks—and this is one of the problems—like a big fishing lure with propeller blades. As the impeller spins, it turns the generator fixed to the boat’s stern. Old-timers may remember how much the fish seemed to like those pricey impellers for the Walker Knot Log, even though they were painted black.
One thing I noticed in Bergen was that one of the towed water generators had what looked to be a homemade impeller, and it is quite probable that the original one was lost. This is one of several problems with towed water generators; they get tangled, fouled in weed, snagged, and lost—sometimes eaten by big fish or sharks. I suppose one reason there might be more of these units here in the north country is the waters don’t have as many surface-feeding pelagic species as we have in warmer climates.
Towing isn’t the only option, though. While I was in South Africa a few years ago, I spoke with the local representative for Duogen to try to arrange a test of this product, a combination wind and water generator. At the time, the company was fairly early in the product development, and I was not impressed with the fabrication. One thing I did like was the apparent ease (the key word is “apparent,” because I did not try this at sea) with which the Duogen deployed: It is suspended over the stern like an electric outboard. In its water-gen mode, it looked very similar to the Watt & Sea hydrogenerators that Practical Sailor contributor Dan Dickison examined during the Velux 5 Ocean Race. These are now available in a cruising version, but they are expensive units, and again we have not tested them.
All of these products have another problem in that they add drag underway. Some owners report speed losses of a quarter- to a half-knot. This isn’t a big deal if they can help keep the ship’s systems running on a long passage, but it’s one more strike against them.
Call me a skeptic, but when I look at the prices for hydrogenerators and consider how much time they will actually be delivering power to the boat, I think there are much better ways to spend my money. If an efficient and convenient dual-purpose generator comes on the market, I may change my tune. But right now, I think solar, then wind still reign in the world of ship-board alternative energy.
We’ll continue our efforts to get a water-generator test going, but in the meantime, I’d like to hear from owners about their own experiences. I’m sure other readers would greatly appreciate the input.