Yammi prop selection, best choice.

[Marv]

Ok, I've been running a Yamaha F115 since 2000, this summer I am upgrading to a F150! Boat is a 22'x5.5' aluminum skiff. And I have run 19-21 pitch without issues and it goes along very well. And when fishing I tend to load up with up to 3k lbs and can still get up on step easily. I know I should probably run the same pitch or are there any differences.
Oh, and I run the Lower Yukon River with a flat bottom boat. I may also end up going with a slightly wider boat if I find one for cheap in my area. TIA.

Marv

 

[Silvertip]

Re: Yammi prop selection, best choice.

With no wide open throttle and maximum speed data its tough to make a recommendation. If you don't have a tach or speedometer/GPS you have no idea whether the prop you currently have is correct. I suggest you visit the Yamaha web site, click on performance tests, select your engine, choose the boat you have (or one similar to it) and then view the test reports. They have all sorts of data from prop type, speed, fuel consumption data, etc.

 

[Marv]

Re: Yammi prop selection, best choice.

Ok, with a 20 pitch prop and empty/light load I run right about 54-5600 rpm and go about 44-47mph depending on the water conditions. 21 pitch I run at times with an empty boat or very light load and see 5200rpm, low, but see 45-48mph. 19 pitch for more load, and see about the same speed as a 20p but have the rpm's around 57-6000rpm, top of the limit.

 

[Silvertip]

Re: Yammi prop selection, best choice.

If you are changing boats, those numbers mean nothing as you are essentially starting from scratch. For a new bigger engine on the same boat, the engine should pull a 21P with no problem and perhaps even a 23P. For your existing setup, it appears the 19P is the best as it has the engine at the top of the rpm band at WOT. 5200 at WOT is lugging the engine as evidenced by the same speed as a 19 but lower RPM. With outboards, pulling the engine off its max RPM at WOT is not a good thing.