Thanks for all your replies.

I've cleared things up this much:

The transmission is designed to run equally fine in both directions. Ratios
are almost similar. The transmission has two "modes" - A and B. A is the
"normal" mode where the propeller-shaft runs in opposite direction of the
engine. B is normally reverse - the propeller-shaft runs same way as the
engine.

Here's the funny thing: From the factory, the boat is delivered with a LH
propeller - which means that the transmission has to run in the "B"-position
to have the boat move forward - i.e. reverse of "normal"!

I called the Norwegian factory to ask why. They replied that "the boat liked
the LH propeller the most"! (Don't know what that means.)

So it all narrows down to this: Assuming that transmission is not an issue -
are there any "hull-issues" that should imply that a given hull simply "runs
better" with a LH instead of a RH - or vice versa?

Anders
Denmark



"JAXAshby" skrev i en meddelelse
...
fair winds, guy. As you point out, if the tranny is designed to take a
prop
going either direction things are fine.

ah, you just might wish to remember that the prop MUST push against the
prop
shaft which pushes against the thrust bearing to push the boat forward.
Got
to.

In other words, the thrust bearing takes 100% of the horsepower
developed by
the engine. That is a lot. In forward.

There is also a thrust bearing needed for going in reverse as well.
However,
as the horsepower used in reverse is much less and the time it is used
is
hugely less the reverse thrust bearing need not be anywhere near as big.

Now, change the prop so the former reverse thrust bearing becomes the
new
forward thrust bearing and operates at 100% power over extended time the
potential to trash that bearing becomes very real.

Most people forget that the prop has to push against something to push
the
boat
forward. That something is the thrust bearing.


Yes, all these things are right ones.

Question is: How has been designed (engineered) the Thrust Bearings Box ?

(sorry I don't know its English code-name)

Our ones are designed and manufactured with a couple of Heavy-Duty Taper
Rolling Bearings, # 322xx, a couple of Rubber
Seals for Lube and Water Cooling devices.

Used in Clam Dredgers working in Reverse... they are tailored to be
operating
in both directions.

Heavy-Duty Bearings in Forward and Light-Dutry ones in Reverse were used
times when Bearings were very expensive... but
actually it is a "poor" spare, requiring different machining on both
sides,
double the Stocks of spares on shelves and
aboard.

But they could be till existing...

Glad to have meet someone involved in Technical matter.

I'm a newcomer in this NG but I will visit it at least once a week.

I hope to have some interesting questions to put to NG attention.


Thank you for your time,

WinXP.