On Mon, 7 Jun 2004 23:03:19 +0200, "Anders Lassen" anders.lassenNEJTILSPAM (at)adr.dk wrote:

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


Yes, it is.

Venetian Gondola is operated by a "single" oar in the RH side: to go straight it is shaped asymmetrical.

The LH side is more curved than the RH side.

Oar turns to left... shaped side turns to right... = straight line.

Same thing happens to a single propeller boat: the reaction to propeller rotation tries to turn boat to right or to lift
direction.

To go straight forward you have to compensate time by time.

To avoid this any Boat Designer has an its own "trick"... maybe a different shape of the hull... maybe a slight
"off-center" centerline... maybe a different tank in one side... maybe battery pack.. maybe something else...

It could be "calculated" or it could have been found during the first tests of the boat...

Right now we are "blueprinting" several propellers for an all new power boat that doesn't wish to plane...

Of course for the Boat Manufacturer is cheaper to replace several propellers than get away a full set of boat moulds...

This is the way: Test... no good... modify... test... no good... replace... test... maybe... adjust a bit.. test... go!

Cheer!

WinXP