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Outboard upgrade
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Wayne.B
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Outboard upgrade
On 21 Feb 2004 07:21:17 -0800,
(nfisherman)
wrote:
I have an 18 ft. Lund Fisherman with a Yamaha F115 motor. I'm
thinking of upgrading to the new Yamaha F150, the maximum rated hp for
my boat. My boat's top speed now is approximately 40 mph w/2 people
and gear. I mostly use the boat for fishing, but there's some
occasional waterskiing.
What kind of performance increase could I expect by adding 35 hp,
assuming comparable props?
================================================== ==
Since speed varies approximately in proportion to the square root of
horsepower in a planing boat, I would estimate a new top speed of 45
to 46 mph. (Doubling the horsepower will increase speed by about 41
percent since the sqrt of 2 is 1.414).
Cruising speed at 75% of WOT will increase by 3 or 4 mph which is not
a big enough difference to be worthwhile in my opinion unless you have
a difficult time staying on plane when heavily loaded.
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Outboard upgrade