Steve,
I completely agree with you. My drive system is regen capable and I certainly won't disable that feature, any "free" power is welcome on my boat. But I will not count on any significant contribution to my charge from regen, it will be a present from Poseidon. Unfortunately, with my boat (a Herrschoff H-28 knockoff), 5kts is just about all I can count on, a 120 mile day would be stretching the boundaries. But like you have stated, 100W x 24 hours will deliver 2.4kWh a day and that will easily cover all but the most wasteful house loads. Now I just hope I can get 100W out of my drive....
On the trimaran, the outboard comes out of the water less than a minute after being shut down, so the only thing that I'm suffering is the weight. My offshore racing org's safety requirements is "Sufficient power and fuel for the boat to achieve a speed equal to the square root of her waterline (5kts for me), for a distance of 30 nautical miles in flat water without a headwind." 3 gallons of gas is technically enough, although I generally carry between 4 and 6 gallons for long races (that extra 20 pounds is worth my peace of mind). Electric is not yet feasible to meet this requirement.
BTW, in the last 3 years, I've spent more on new sails for the trimaran than my entire drive conversion with LiFePO4 batteries in the ketch. Don't let my wife find out.... :)
Fair winds,
Eric
--- In electricboats@yahoogroups.com, Steve Dolan <sdolan@...> wrote:
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> Eric,
> I would suggest that the regen may not be practical on a 2 or 3 hour 5 knot sail but what if you sail for a distance and use power for the stereo or a few gauges? What if the total usage of power during an overnight run equaled your regeneration rate? "Anything that is free is for me" so any power I can get is good thing. It may not be able to fully charge your batteries but it's better than nothing unless the drag exceeds the benefit. What if you're on the back of a 20 foot wave heading down and can get 6 amps (or more) all the way down and half the way up the next wave? You could run your motors at 2 knots and gain 50 miles in a 24 hour period at no cost. I didn't do the math but should be close. Anyway even a little regen is better than no regen. But then again the majority of boats here are smaller and don't travel as far. I think if I had a smaller boat and it was free or included in the package I would think of it as a plus. Now if I had a tri (I do have a MR2 spyder) for nothing but speed the weight would definitely be a consideration. I'm surprised you don't just have a couple of paddles! You could probably still get up to 5 knots :o)
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> Steve in Solomons
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> I know that my 30' ketch has only touched 6kts a couple of times in over 10 years. 5kts takes a solid breeze for my old boat. So I don't expect much from regen from my electric drive, even when headed offshore to our local islands.
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> Alternatively, my 27' trimaran has hit 6kts boat speed in only 5kts true wind. If I converted that boat to electric, that kind of performance would no longer be possible. I'm not willing to sacrifice my good runs at 15kts+ boat speed to go electric. The 9.8hp outboard is auxilliary power that works for me.
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