T-Pain Is On A Boat: Re: [Electric Boats] Re: hydro generator

Hi Dave,

Its really difficult to tell what it is. I've tried to do some tests sometimes but its really a guessing game. I've rarely been able to keep my bat sailing at a really steady speed—I find that the speed is always fluctuating just slightly by a fraction of a knot, up 0.2 here , down 0.3 and so on. And so when I do raise or lower the motor, its not clear whether changes that I see have come from drag, or from slight changes in wind, or boat directional changes and so on. It could be half to one knot.

But this difficulty of measuring raises an interesting point. If its so difficult to tell how much drag there is, what does it matter?

I'm mostly never in a hurry to get anywhere, after all it is a sailing boat, and for me the enjoyment is as much in the trip as in getting there.

And another aspect of this is the advantage of this in fickle winds, such around Pittwater (Australia) where I have the boat, and where the waterways are fiord-like and can generate fickle winds on the narrow creeks. When the prevailing wind is say 10 knots, the wind at water level can be 5 to 15 knots and changing from moment to moment. Then by running the Torqeedo at a low speed, say 150 watts, it is enough to help her through lulls and knocks, and to keep her going through a tack, especially with just the jib up. Then when the wind picks up to over 10 knots it will be regenerating. So this kind of sailing is "for free" in that the power used in the lulls can be won back in the gusts. As well as being much easier to sail cos she doesn't keep stalling, and just as quiet :)

Cheers

Chris

On 20/04/2011, at 11:24 PM, Dave Kellogg wrote:

Chris,
I'm wondering about drag while you were making the 18 amps. On your tri that speed isn't much of a problem and the size/weight of your boat shouldn't give you much of an indication of slow down, I'm just curious if you noticed.. Dave K

From: "chris@currentsunshine.com" <chris@currentsunshine.com>
To: electricboats@yahoogroups.com
Sent: Tue, April 19, 2011 11:14:40 PM
Subject: Re: [Electric Boats] Re: hydro generator

Hi Erik,

I've seen some regen on Current Sunhsine which has a Cruise 4. Its
not recommended by Torqeedo, so keep that in mind if you want
experiment with this. If you do it you may lose warranty.

If I set the throttle at around 50 watts or some other low number,
then when the boat is sailing the power requirement quickly drops back
to zero, and then from around 5 or 6 knots I begin to see 1 or 2 amps
coming in. I've seen as high as 18 amps when she was doing about 13
knots. And it has been regenerating when I've had her at 25 knots and
the motor was screaming but I did not get a chance to see what the
amps was. That was accidental :) But it didn't blow up the motor, so
I think they could be robust enough for more genatle use.

This regen is at 48 volts so at 18 amps that was a respectable 900
watts coming in. But even at 2 amps, thats 100 watts and is enough to
easily meet my house load requirements and a bit more besides.

Cheers

Chris