uncupped to a cupped prop

[2000Fisherman]

I have a 2001 Yamaha Vmax 150 hp with a 14 1/2'x17p uncupped prop. Im looking at moving into a cupped stainless steel 17p. Just by going to a cupped prop will that decrease my RPM's slightly? The thing is now im running on the upper limits of my engine rpm's and sometimes over. I believe im running at around 5500-5700. I dont really want to drop the rpm's by 400 which would occur if i went to a 19p. <br />The rpm's i m running at are also with just 2 people in the boat and half tank of gas. So i know when i load it up with 3-4 i will get an rpm drop also. Thanks, Jason

 

[Kenny Bush]

Re: uncupped to a cupped prop

Cupping will not make that much of a difference in RPM's, but it will make the prop hold the water a little better. Similar to a rear spoiler adding a little extra downforce. If it were me, I would switch to a 19p prop due to your RPM range being at the high end. I think you will like difference in speed. It will raise your speed at the optimum fuel efficeincy.

 

[2000Fisherman]

Re: uncupped to a cupped prop

Thanks for your advice bushcat. A little extra speed would be nice also.<br />Is there a brand of Stainless steel that allows a better "rooster tail"? Its not a real important thing but its kinda cool to watch.

 

[Boatist]

Re: uncupped to a cupped prop

Fisherman<br />I agree with Bushcat, the 19 pitch will gain you some speed and reduce fuel cost with a little slower hole shot. If you are going from aluminum to stainless with cupping the cupping will decrease your rpms a tiny amount but the thinner blades of the stainless will cause more rpms gain than the cupping looses. Keep the old prop for when you are draging skiers or toys with a boat full of people.