Sunday, 20 July 2008

Sailboat Towed Generator for More Onboard Power

The debate between wind generators, towed generators, solar power and the so called 'gensets' has been raging for years.
The fact is that in these days with all of the environmental issues surrounding us, installing a genset is just a non issue. A combination of air, solar and water power generation is the only solution for most cruising sailboats. By most we are referring to yachts up to 50ft. approximately which would comprise 90% of cruisers sailing our oceans.
All these options draw their energy from the natural elements we are passing through whilst sailing - with a nil carbon footprint. They take up little room and are silent - perfect!
Stack this up against the diesel generator which is noisy, requires a lot of inboard space, uses diesel fuel, needs constant attention(servicing), and with a poor power output - you do not want a diesel generator running all day!
I personally used a combination of a wind generator and a water towed generator. The wind generator is fine when sailing to windward, but output drops off a lot when sailing downwind. So the back up was a towed generator which produced 9 - 11 amps constantly when sailing downwind at 8 - 9 knots.

This pumped in enough power that would run all the boats' power needs effortlessly, including the refrigerator and water maker, which enabled us to arrive at every port with full water tanks.
I ran it during the day, retrieving it onboard again at sunset.
Technology has moved on and the units you can now purchase are even more efficient.
Here is an extract from the website The Green Blue in which the benefits of towed power are discussed.
The Green Blue - Energy Saving Tips - Towed Power
‘Another way to charge your battery while cruising is by a towed water generator. These devices are easy to use and are powered through a rotor towed on the end of a 33 metre line. An example showed that 3 Amps/hour was produced at 4 knots and 5 Amps/hour at 5 knots.’
As discussed in the May energy saving tip on wind turbines, the average yacht these days, is more often than not fitted out with a wide range of electrical equipment to help make navigation simpler, safer and more enjoyable for the skipper and crews onboard.
Anyone who owns a yacht actually already owns a large wind energy generator, and that is the yacht itself. The average wind turbine suitable for mounting on a yacht may span 7 - 10 square feet of air stream, whereas the sail of a typical cruising yacht will of course intercept an area far greater than this.
As a result an easy and efficient way to maximise power generation for your battery whilst cruising is by drawing energy from the yacht's movement through the water rather than directly from the wind.
This is where a towed generator comes into its own. Many yachtsmen consider towed water generators too much trouble, but this is an efficient way to get a lot of energy out of the wind, particularly when on long passages.
Originally the generators we designed just for towing but since the first was developed things have changed and there are all sorts of varieties available to choose to suit your needs. The most modern designs can be used as a towed generator whilst moving and can then be adapted to work as a wind generator when anchored and stationary.
Article reproduced courtesy 'The Blue Green' with image from Ampair.
You can read more about power generation and towed generators in my ebook 'Voyage of the Little Ship 'Tere Moana' downloadable from my website


Anonymous said...

Hi Vincent,
So can you tell me how the towed generator works at 14 knots? I wondering how they would work on a multihull and have read that at 7 to 8 knots, they come to the surface and "walk" back and forth - port to starboard. I think they are a great idea, but fear that they would not work out well on a faster boat.
Rick Emmet

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