On Fri, 25 Jun 2004 10:13:22 -0400, "Marty S."
wrote:

Other than picking up weeds and possibly hitting bottom, then the motor is
as efficiently moving the boat at it lowest mounting point as if it is
raised to be even with the bottom of the stern?

At it's lowest point, force applied to the shaft will "try" to raise
the bow of the boat ( I seem to remember "vectors" from my school
days) and raising the bow with a trolling motor is wasted energy.

I would imagine that the best place to apply a forward force to a boat
would be right at the water line. Imagine pushing a boat in shallow
water. Obviously, with a propeller, this is impractacle.With the top
radius just a few inches below the hull seems the best compromise.

If you have a regular outboard too, you may want to set your trolling
motor skeg slightly lower than your gas engine. This will help prevent
you digging your main prop into the mud in shallow waters and having
to jump out and free it!