Choosing and Fine Tuning Your Prop |
I have seen a lot of questions on this and other sites about picking the correct prop for your boat and fine tuning it once it's on the boat. Let me assure everyone it's a very simple task. You need three things.
Here is the fun part. Run the boat across the lake at Wide Open Throttle. Note your rpm rate. Let's say your turning 5000-rpm and you have a 23 pitch prop and your redline is 6000. That means you are 1000 rpm short. Here you have a couple of options. One is try a 22 pitch prop. Another is find a good prop shop. They will be able to adjust or tune the pitch of your prop. They may not be able to find you a 1000 RPM from your particular prop. If that's the case you may have to trade your prop in for a 22. For conversation sake, lets say that's what you have to do. You put it on your boat and take off. At WOT you find your running 6400.
No you don't have to buy another prop. A good prop man can do wonders with a prop.
He should be able to reshape or tune your prop. This is called adding cup to
your prop. They do this to reduce the RPM and to raise the RPM he will remove cup.
There are limits as to what they can do. These skilled craftsmen can only do so much. Just
listen to their recommendations.
The key is consistent boat operation. Weight and operating conditions have to be identical
when testing props.
However let me caution you. If you test your prop in the dead of the summer heat shoot for a few 100 PRM LESS than redline. In the spring and fall the cool weather will let your motor run better and your RPM will go up. Accordingly in the summer max RPM will go down.
I hope my feeble attempt at writing takes some of the mystery out of choosing and tuning the correct prop for your boat.
Drop me a line if you have any questions.
John
Johnduke@edge.net