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megabite
 
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Default Selecting HP for given hull (outboard)

Old proverb: "Where there is loss there exists gain, Where there is gain
there exists loss" I think it's merely a question of hair splitting. Opt.
for the Max. HP. once on plane, back the rpm's off and just cruise. Max HP
might be an edge in the resale side of the equation.
"roy" wrote in message
om...
Am looking at a new boat approx 20-21 ft in length with 15 degree
deadrise, sort of a flats type hull shape for shallow water. The
manufacturer rates the transom for up to 200 HP, the dealer claims
that 150 is plenty and that anything larger is a "waste of money" in
both initital cost and operating costs. He also claims a speed
increase at WOT of only 2-3 MPH.

I have looked over the Yamaha website for performance on specific
power packages but can't seem to find the same hull with two different
HP performance tests.

My previous experience indicated that by having maximum rated HP on
the transom that one could turn a larger prop, say a 21 inch pitch
while the less powerful engine would force the prop pitch down to a 19
or less.

I realize that at WOT a 200 HP will burn more fuel but it is my intent
to operate for the most part in the 30-35 MPH range on a hull that
will offer in excess of 50 MPH. Will the reduction in RPM on the
larger motor to achieve a given cruising speed provide adequate
additional fuel economy and performance increase to justify the
increased initial expense?