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posted to rec.boats.building
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First recorded activity by BoatBanter: Aug 2007
Posts: 383
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Charging
Richard Casady wrote:
On Sun, 30 Sep 2007 00:44:04 -0400, Wayne.B
wrote:
On Sat, 29 Sep 2007 20:10:01 GMT, (Richard
Casady) wrote:
there must be some high output, low rev alternators / generators out there
that can do the job.
High output and low revs just don't go together. Halving the rpm tends
to double the size and weight. There is a reason why they invented
gearing. I think maybe you need a big prop and a gearbox.
Changing drive pulley size can improve alternator output a lot more
easily than props and gear boxes. Another strategy is to install a
high output alternator and run it at a reduced rating that still meets
your needs.
The discussion was about a rope trailing a boat, with a prop on the
end in the water, turning the rope and the generator attached to the
boat end of the rope. Where do you get a pulley? It is a direct drive
we are discussing. Higher output requires either more torque or more
rpm, since power is the product of the two.
torque available is determained by the prop. No diddlin with the
generator can change that. Only a higher output prop can turn a higher
output generator. This means more diameter and /or more blades. There
is no way around it.There is no available energy from 'nowhere'.
Casady
A ROPE???
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