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Did I break some kind of rule with that last
post?<br><br>If I state it more generally is the following
OK?<br><br>How much energy is generated during regeneration by a
4KW motor?<br>If you have, oh lets say, a 13 inch
three blade prop for example, how much energy(lets say
in Watts) is created at 1 knot, 2 knots, 3 knots, 4
knots, 5 knots, and 6 knots?

Regeneration depends on the air, hull speed of
vessel, prop size and where the prop is located in
reference to hull form. With a 13" prop i am guessing that
the vessel is only 25 to 28 feet with a slim hull.
There will be no regeneration until about 4 knots and
at that time I will guess(and I do mean guess) 400
watts. At 6 knots which sounds to be 1 knott or so over
the projected hull speed of a 25-28 foot boat...I
will guess about 700-900 watts. If you are three foot
or better seas the wave action will add an aditional
300-500 watts. Truth is...every prop and hull form is
different and it is hard to really estimate it without
further information. Going the other way....with a 19"
prop in heavy air at 5 knots you can expect 2-3 KW.The
key to boating efficiency is prop size...the bigger
the better...it also follows Newton's laws that this
would stand for regeneration as well.

Like was previously stated prop sizing is the all
important factor. In regernation and also in propulsion. If
you haven't read it I suggest you get a copy of Dave
Gerr's "Propeller Handbook". It is well worth the time
it takes to read it. I have an excel spread sheet
that I have developed that will also aid you in you
propeller sizing. All realy did is take the known propeller
formulas that are in Mr. Gerr's book and matched them to
some Physics formulas and came up with a way of
modeling performance. of course like any model the results
are only theoretical but at least it will allow you
to play some what if games. It also is useful for
tuning your boats performance. If you would like I'll
send you a copy. Just E Mail me at Donaldbaer@...
and I will send it to you.<br><br>Regards<br>Don Baer