Correct Propeller

[tommiez]

I am new to the board. I live in Vancleave Mississippi on a bayou off the Pascagoula River. I have a 2003 21SV. I put on a Stryker T Top 5 years ago. The boat came with a 150 Carbed Yamaha. It would run 44  MPH but burn about a gallon a mile. I repowered it with a 2004 Honda BF150.  It would run 40 mph, which is 4 mph slower than the 2 stroke. I have been messing with trying to get the correct prop on it. I had a 15 pitch prop on it, tried a 17. still only 40 but higher rpm. I tried a 19, still pretty much the same. I put on a jack plate, that helped but only 1 mph . Now I have a 21 pich and only turns 5600 rpm, still only goes 40 but now if I am running 4200 rpm I can go 32mph. With the 19 pitch at 4200 I am only going 25. Do yall have any suggestions. I would love to get back to 44. Thanks Tommy

[gnrphil]

Firt off what different props did you try, diameter, cupping and rake all make a difference. How is the motor height ?, can you see the AV plate while up on plane ?.
From your numbers above it looks like a 19 is where you need to be, it's possible the 150 Honda hasn't quite got the power the Yamaha had.
 Aboard

[tommiez]

First prop was a Solas 15, then 17, then 19.. I am dealing with a prop shop in Woolmarket. Then he gave me a 21 pitch to try. The 21 pitch doesn't give me much top end. Just 39-40 mpg but at slower speeds I like it.. at 4500 rpm I am doing 32mph.. which is a good cruising speed for me in the river. I put a jack plate on it and am messing with raising the  motor some each time I go out. seems to me there is a lot of spray that comes off the back of the boat when your running making it hard to see the bottom of the motor. right now I am about an inch higher then the highest point where it would be mounted without the jack plate. Not sure if that makes sense or not..the rpm with the 21 is 52-5500. According to Hondas website it makes 150hp at 5500 rpm..