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Old 14 October 2013, 23:05   #21
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Country: USA
Town: Pooler, Georgia
Boat name: not applicable
Make: Avon
Length: 3m +
Engine: Outboard
Join Date: Aug 2011
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The difference was 1 MPH. Not worth the purchase except that the 9 inch is better for a loaded boat.

People overestimate what a few horsepower does for speed and also what difference a prop makes as long as the motor is running in the proper RPM range. Cupping or stainless can make a bigger difference, but that is in expensive trial and error territory.

On my old 18, a 1/2 in pitch difference with a cupped blade made a tiger out of the engine and was the only prop we would use. It ran as fast as the boat did when fitted with a 25 HP 33 cu in. Had Evinrude continued to make their 22 cu in engine, one of those engines would be on the boat today.
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Old 14 October 2013, 23:20   #22
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Country: UK - England
Town: Looe/Fowey
Make: Honwave 4.0
Length: 4m +
Engine: mariner 20 4 stroke
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This was a lot simpler with my 90 2 stroke on bumpy days the 19p would go on and on flat days the 21
Power for every occasion
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Old 15 October 2013, 01:30   #23
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Country: USA
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Length: 3m +
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Loco, if I could have found a 2 stroke 18 HP Tohatsu or Nisson motor, I would not have bought the 15 Yamaha. It was one of the last 2 strokes available in the area at the time it was purchased and they were taken off the market that year.

We slow troll a lot for fish, so the 15 works well. I generally lean out the carb for lower trolling speed, but the needle is protected from adjustment for emissions on the newer 2 strokes

We are on the same page about props, but I admit I do like to play with performance on my fishing boats. Guess that is from hanging around engineering folks for so long

The motors are used on several different boats, but I have culled the herd over the past few years. Heart attack, so the canoe was given away; too old for duck hunting, so the Geenoe type was sold; gas prices got so high that the big boat was given to a friend. Along the way a 9.8 Nisson joined the family and is one nice motor for the inflatables. Can't help it, but I love the water and am blessed by a wife who shares my love of the outdoors. People say she spoils me you know.
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Old 15 October 2013, 20:02   #24
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Country: UK - England
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Make: Honwave 4.0
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Engine: mariner 20 4 stroke
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thanks for your advice i will post on this subject again after i have bought a new prop
just to decide weather to get 9.5 x 11 or 11.5
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