Prop Re-visited

[SMURPHY]

Could some help clear up a few things for me???<br />I have 2001 merc 150 XR6, I have two props one is a quick silver Alum 14.25X21 WOT 5600+@65ish mph(would probably go over max RPM) and a michigan wheel 13.75X21 5000rpm@57mph maxed out. I'm not concern with speed I'm concern with max RPM.<br />Why do I get lower RPM with the smaller Prop?? It seems more logical to me that the reverse would be true - smaller diameter higher RPM?? Could it be because the merc prop is flexing alot and the michigan prop is just a better prop??<br /><br />BTW, I tried a michigan wheel 13.50X23 and had a really hard time getting up on plane.<br /><br />I'm trying to prop it for all around use, and I thing I have done that with the 13.75X21. I'm just the curious to this pheonomina(sp?)<br /><br />Thanks<br />Shawn

 

[JB]

Re: Prop Re-visited

Yo, Murph. This is just a guess, but I suspect that your Michigan Wheel prop has thicker blades (more drag), less rake and probably more cup (more bite). If I am right, it is the most dramatic demonstration I have seen of the effects of subtle design features on prop performance.<br /><br />I agree that your Quicksilver is the optimum prop for your package.<br /><br />Red sky at night.<br />JB

 

[sony2001]

Re: Prop Re-visited

Stick with Quicksilver! Its more efficient.Your present size cupped or a 23" are good choices. Probably 21" cupped would be the best.