Saturday, March 6, 2010

Re: [Electric Boats] propellers

 

Kevin,
 
Do you know how many watts are required to match the prop speed to the boat speed? 
 
If you had a readout for motor rpm you could have a little chart telling the "0 slip" rpm vs. boat speed so you could know exactly how much throttle to apply.
 
Hmmm...
 
Denny
 
----- Original Message -----
Sent: Saturday, March 06, 2010 12:49 AM
Subject: Re: [Electric Boats] propellers

 

I believe, but can't yet prove, that the one area where "regeneration" might actually be practical is in what Kevin P calls "electrosailing" - matching the prop rotation to the boat speed so that it's regenerating about 50% of the time (very low wattage mind you) The point of this is not really regen, but rather nullifying the prop drag and getting the extra 1/2 to 3/4 knot of speed. Over a sufficient distance, this extra speed is the practical equivalent of a feathering prop (without the drawbacks) and nearly net zero energy use.

I currently have a 3-blade, so the above is more necessity than choice.

-K

--- In electricboats@yahoogroups.com, "dennis wolfe" <dwolfe@...> wrote:
> I bet a large diameter, high aspect ratio 2 blade prop would give excellent performance as a sail aux drive, especially if a method could be devised to lock the prop in the vertical position hiding in the wake of the skeg. A folding prop that would work in reverse would be even better.
>
> Denny Wolfe
> www.wolfEboats.com
>

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