On Sat, 11 Jan 03 00:31:53 GMT, (Anonymous)
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.

Casady

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.

(Anonymous) wrote:

there must be some high output, low rev alternators / generators out
there
that can do the job.

If you want high output, low RPM, think Leece Neville.

Something like a 4800.

By comparison, almost anything else is a toy.

It WILL require a dual belt drive.

To fully utilize the output, you will need at least an 800AH battery
bank.

Lew

There is a wind and water charger device that has both an air
propellor and a water propellor. Mounts on the transom and either
swung into the air or into the water with the appropriate prop fitted.
I've got Leece Neville alternators on the engine - 24v 95A and 110A -
and changed the pulley size to improve charging at lower revs, but not
exceeeding the max rpm at max engine speed.

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.

There has been no mention of drive belts so far. Where did you even
get a pully? Nothing in the discussion to hint at one's existence. And
there is. in general, no difference in weight and complexity
comparing gears and belts.

Casady

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

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???

On Tue, 02 Oct 2007 15:31:22 GMT, (Richard
Casady) wrote:

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?

I missed the original post and somehow got the idea we were talking
about a conventional alternator, not a towed device. Sorry for the
confusion.

On Tue, 02 Oct 2007 22:08:46 -0400, Wayne.B
wrote:

On Tue, 02 Oct 2007 15:31:22 GMT, (Richard
Casady) wrote:

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?

I missed the original post and somehow got the idea we were talking
about a conventional alternator, not a towed device. Sorry for the
confusion.

I am not laughing, I do that kind of thing regularly.

Casady