1982 Howard whaler prop size

Slo Ro

Recruit
Joined
Oct 3, 2012
Messages
2
I have a 1982 Howard whaler with the 5.7 mercruiser not sure the ratio of the drive , and it currently has a 15.25 x 15p aluminium prop on it , i can get it to turn 4500 -4600 rpm and thats about 41 mph (per gps ) and cruises about 31- 33 mph at about 3600 rpm , seems a little high to me , should i go down in size to a 14.5 and more pitch maybe 17 , for better cruising speeds , or just leave well enough alone

thanks
 

Bifflefan

Commander
Joined
May 27, 2009
Messages
2,933
Re: 1982 Howard whaler prop size

17p and 19p are the most common pitch of prop. I'm a little amazed that you have a 15p on there, unless your boat is a larger one.
The ratio is stamped on the out drive and is probably a 1.50.
Is you 4500 to 4600 at WOT, or are you holding back some?
Your numbers look fine so you should be good to go.
Also dont worry about the diameter, as long as it will bolt on the drive, let the manufacture worry about that part. "P" is what you need to look at.
 

Slo Ro

Recruit
Joined
Oct 3, 2012
Messages
2
Re: 1982 Howard whaler prop size

Thank you for the rsponse , and the boat is 22 foot and im thinking about maybe 3500 to 3800lbs with full tanks and the typical STUFF thats carried , and yes that was at WOT , and i get the same RPMs with the bimini up or down , i asked about the prop diameter , only because when i mentioned that size to the person at the marine shop by me he had a surprised look on his face , well maybe i will try and find a 17p and see what happens

thanks again
 
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