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?

One issue to consider is the engine displacement of the two outboards you
are considering.

Many companies use the same block for many HP configurations. This means
that you might see a 150, 175, and 200 with the same block. In *this* case
both outboards weigh the same so the 200 would give you better performance
and perhaps slightly better gas mileage at throttle settings under WOT, but
prolly get slightly worse mileage up at the top-end.

When comparing outboards check the displacement and weight - those being
equal, I'd opt for the higher output version of the block.

-W




"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?

"Clams Canino" wrote in message
news:iXAfb.677583$Ho3.144064@sccrnsc03...
One issue to consider is the engine displacement of the two outboards you
are considering.

Many companies use the same block for many HP configurations. This means
that you might see a 150, 175, and 200 with the same block. In *this*
case
both outboards weigh the same so the 200 would give you better performance
and perhaps slightly better gas mileage at throttle settings under WOT,
but
prolly get slightly worse mileage up at the top-end.

When comparing outboards check the displacement and weight - those being
equal, I'd opt for the higher output version of the block.

-W


One more thing, I have never heard anyone complain of too much horse power!
Greg

Yanno - actually - I have. sigh

I knew some guy with a '87 115 on a little bass boat - said it was "way too
much motor" for the boat. LOL. Now, I'm using the same basic block on the
PM-II and I could think of a thousand things I wanna do to trick it out to
make about 175hp "when I have the time". LOL

-W



"Greg O" wrote in message
...

"Clams Canino" wrote in message
news:iXAfb.677583$Ho3.144064@sccrnsc03...
One issue to consider is the engine displacement of the two outboards
you
are considering.

Many companies use the same block for many HP configurations. This
means
that you might see a 150, 175, and 200 with the same block. In *this*
case
both outboards weigh the same so the 200 would give you better
performance
and perhaps slightly better gas mileage at throttle settings under WOT,
but
prolly get slightly worse mileage up at the top-end.

When comparing outboards check the displacement and weight - those being
equal, I'd opt for the higher output version of the block.

-W


One more thing, I have never heard anyone complain of too much horse
power!
Greg

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?

"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?

Not on the lightweight hull you are describing. What's the difference in
weight between the two engines, not if you are planning to run the motor
in the 30s...

I'd guess the difference in top end would be between 3 and 5 mph, a
little more than your dealer sez.


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