re: Propeller Polarity

Rdement1@aol.com
Wed, 14 Jul 1999 16:19:44 EDT


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West Wight Potter Website at URL
http://www.lesbois.com/wwpotter/
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<< One
concern of mine is the possibility of re-installing the propeller on
backwards. >>

On MOST outboard motors, it would be extrememly difficult to mount the
propeller on backwards. Especially the smaller (3.5 and below) engines. The
prop will usually be smaller on the aft end. Not only that, but most engines
turn the prop 'right-hand', (or clockwise) if looking at it from behind.

<< Obviously the boat will run the opposite of expected, but what
kind of damage is possible? >>

If you are 'lucky' enough to get the prop to go on backwards, it may go
opposite of what is expected. You may also immediately catch the prop on the
skeg (the little fin on the bottom of the O/B) Most smaller engines use a
composite prop, which would tear a blade off.

If by chance you do get your prop on backwards, and the motor runs without
err, you can still cause internal damage to your lower unit. All the guts in
there are designed to have the forces and pressures on certain components.
Even a motor with a reverse gear, wouldn't last all that long going in
reverse all the time. Some motors use a 'thrust bearing', which alleviates
the thrust from the internal parts of the gearcase, and transmits it to the
stronger parts of the outer housing.

If putting a prop on backwards is an issue, use a scratch awl, 'sharpie pen',
or even a dab of white-out on both the prop and the lower unit to mark which
way it goes BEFORE removing the prop....

Cheers,
Russ de Ment
Borrowing Grandpa's P-19
Silverdale, WA