Prop Confusion again

[mike1234tampa]

Hello,<br /><br />I have a 1972 231 Crysler Courier hull which is a 18.5 foot tri hull, it is a heavier boat, I just got done restoring it. I hung a 1973 85 hp Johnson on it. The first time out I spun the hub (thank for th help in a previos post). Anyways I dropped the prop of at the repair shop, told me it was a 17 pitch prop, told me I should try a 13 or 15 pitch prop because I pulled to many RPM's and that is what spun the hub. I explained to him the no, sitting for 17 years is what spun the hub. <br /><br />Now am I wrong, but if I had pulled to many RPM wouldn't I go with a 19 or 21 pitch prop? <br /><br />I never was able to see what my RPM was at WOT.

 

[ob]

Re: Prop Confusion again

yeh,That guy got his pitches bass ackwards.Best to get your prop rehubbed and water test rig.Insure that the motor is capable of its recommended WOT operating rpm.On your engine that would be at around 5500.Any lower and I would see about propping down to attain more.Any higher than 6100 which I don't think you will be,and you would want to increase pitch.<br /><br />I'm guessing a 15" is where that motor will want to be propped pushing your boat.Of course that is without knowing the dry hull weight and is just a guess.

 

[Dhadley]

Re: Prop Confusion again

We routinely run props with rubber hubs above 8000 rpm. No problem. And how did he know what rpm's youre turning if you dont? And as OB said, you are correct. Going to higher pitches will decrease rpm's. Not lower pitchs.<br /><br />Spinning hubs has to do with the condition of the rubber and heat.<br /><br />Do we see a new prop shop in your future?

 

[mike1234tampa]

Re: Prop Confusion again

Thanks for the input, I am picking up the prop tommorrow and will see what happens saturday, Sunday is Easter, wife says no boating <br /><br />And a new prop might be in the future, after I see how the 17 pitch does, it is stainless, would hope it works OK