Joe wrote:
(N1EE) wrote in message . com...

(Joe) wrote


(N1EE) wrote



Joe,

Have you considered that the previous owner of a
boat might bave screwed up and put the wrong prop on?

Yes

Then you as the new owner might make the false assumption
that replacing the prop, with an indentical one, would be
a solution.

No, if it slipping as defined by cavitating then its pitch is to
great.
And if I put another opposite rotating prop on it would not be
IDENTICAL.

Joe, you've been drinking TOO, not "to" much.



And I can not think of any marine transmission that does not have the
same ratio forward and reverse.

It shows how limited your experience is then doesnt' it?



Name one marine transmission that has a diffrent ratio in recerse than
it has in forward.

I already posted a link to one of the most common small marine engines.
Their transmission uses different ratios for all options, except the
saildrive.
http://www.yanmarmarine.com/products...0_TechData.pdf




That would be a big mistake by the mfg. Can you guess why?


So I checked the bigger Yanmar, such as the one used by the PDQ
Powercat. This is offered with the Hurth ZF30 which uses different
ratios for fwd/asn, but is clockwise only. If you want a
counter-rotating pair, there are several with the same ratios, including
the ZF25, which is what PDQ uses. Of course, this is of little interest
to most sailors - even catamarans don't usually use counter-rotating props.

http://www.yanmarmarine.com/products...E_TechData.pdf