Prop size

[wireguy]

How do I find out the correct prop diameter and pitch?
I just bought a 1987 Sylvan 17.5' Bowrider (Fibreglass) with a 2.3L 4cyl. Ford engine and OMC Cobra outdrive. I think all the previous owners have strayed too far from what should be on the boat but am not sure how to go back?

[timgoz]

Dave Gerr wrote "The Propeller Handbook". Though I have not read it, his other book "The Nature of Boats" was quite good, and I've heard the prop book is very informative & well written.

Hope this helps.

Welcome to the forum Wireguy.

Take care.

Tim

[switlikbob]

Originally Posted by wireguy

How do I find out the correct prop diameter and pitch?
I just bought a 1987 Sylvan 17.5' Bowrider (Fibreglass) with a 2.3L 4cyl. Ford engine and OMC Cobra outdrive. I think all the previous owners have strayed too far from what should be on the boat but am not sure how to go back?

Maybe you can tell us your speed, correlating RPM and what the max rated RPM is as well as the current prop you are using...

[PAR]

Find out what the proper operating WOT (Wide Open Throttle) RPM is for your engine and check this against the actual RPM's you do pull at WOT. If you're off by more then a couple of hundred RPM, you could benefit from a new prop. The idea is to size the prop so your engine can pull full RPM at WOT.