View Single Post
Old 04-26-2012, 12:13 PM
EJ OJPROP's Avatar
MC Fanatic
Join Date: Mar 2005
Location: East Tennessee
Posts: 751
Originally Posted by TRBenj View Post
I have seen worn out props that act like youre describing. They turn consistent speed vs. rpm at skiing speeds, but flex at WOT, causing extra RPM's that dont translate to speed. I consider props like that to be either worn out (if old and springy) or simply inefficient (meaning they dont turn RPM's into speed very well at the top end).

I have little experience with the newer XMP OJ's out of the few Ive tried for the 1.23's (lower prop RPM), but I know someone who saw the exact same behavior youre describing with a new XMP on a 1:1 boat. The last few hundred RPM didnt speed the boat up.

In his opinion, the Acmes arent as susceptible to this phenomenon... they turn RPM's into speed a bit better. You may want to try a comparable sized Acme... my guess is that it will turn similar RPM's at skiing speeds, but will drop your revs slightly at WOT, if it bites and pushes the boat instead of flexing.

I would not expect a steeper prop of the same design youre using now to help performance in any way.
Tim - Our blades are thicker than that of the other brand. They will not however flex to the point of loosing enough pitch to change MPH. A thinner prop will run a bit better top end, 1-2 MPH, than a prop with a heavier root. While I understand the need for speed, we have always defered to durability and longevity and had thicker blade sections. I can thin a prop down for MPH but it will bend at the slightest impact, which most guys do not prefer to gain 1-2 MPH.

As I said earlier, a higher pitch prop will not help the overall performance, no matter who makes it.
Eric Johnson
Johnson Propeller Co., Inc

Reply With Quote