Yamaha

[Wuggyboy]

Hi everyone I've s thirty horsepower yam 4 stroke which is only putting out 5200 rpms wot. I've been advised to change the prop to a 12.2 x 6 pitch prop. Has anyone done some thing similar. I've been told I'll gain 400 rpms. Will this affect top speed.
Cheers
Willie

[boscoe99]

What brand, model and pitch propeller are installed now? What is the size of the boat? How is the boat loaded?

[Jason2tpa]

After answering boscoe's questions, you can use prop pitch rule of thumb....1" of pitch = 150-200 rpms. Increasing pitch decreases rpms, decreasing pitch increases rpms. This rule of thumb is not exact, more of a guide to help you narrow pitch selection.