28 pitch to 26 pitch

mystic97z

Recruit
Joined
Jul 25, 2009
Messages
2
hey guys, have a 97 266 crownline ltd, i believe it weighs 4800 lbs. the guy before me went from 26 to 28. if i go back to 26 pitch props (bravo 3) how will my boat behave compared to the 28's it has now

also, kinda new to boating. this boat has a 454 mercruiser that is pretty mechanically sound. sounds great and runs great. but it has 561 hours on it. is that alot? what would be a good "safe" cruising rpm? i have been out at 2800-3000. fuel economy aside, what is a good rpm for me to cruise this boat at and be safe on the engine?
thanks
-Jason
 

junior1113

Senior Chief Petty Officer
Joined
Jan 29, 2009
Messages
763
Re: 28 pitch to 26 pitch

need to know wot rpms. that meens everything when reproping so no lugging or over reving is happening. good cruising speed is betwwen plane speed and top speed. but life of an engine is all about wot rpm.
 

mystic97z

Recruit
Joined
Jul 25, 2009
Messages
2
Re: 28 pitch to 26 pitch

anywhere from 3500-3900 rpms

why do you say engine life is all about wot rpm's , if your at wot and not reaching my 4500 max that is a bad thing?
 

wca_tim

Lieutenant Commander
Joined
May 28, 2007
Messages
1,708
Re: 28 pitch to 26 pitch

anywhere from 3500-3900 rpms

why do you say engine life is all about wot rpm's , if your at wot and not reaching my 4500 max that is a bad thing?

YES!!

You should be propped to hit somewhere around 4200 rpms. overpropping (your current situation assuming that something else like a really dirty hull, poor engine performance, etc... isn't slowing you down) is hard on an engine because it is bearing more of a load than it was designed for at a given rpm.

I would make sure the engine is in good tune and running well and that the hull is relatively clean, then get a fresh read on your rpms at wot. From there you'll have a much better idea of where to change your prop pitch to.

Note that when you're max speed is at wot, it turns out for most engines that your cruising sweet spot just happens to be somewhere near max torque... a good situation.

If you're overpropped with the 28s as I suspect, dropping back to 26s will not only give you a better holeshot and pick up your rpms, but will also increase your top speed... you put the engine nearer to it's max horsepower at wot which is what will yield the highest top speed.
 
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