Another Prop Question

[Silvertip]

Your assumption is correct. Stainless props are indeed more efficient than aluminum hence the rise in RPM. Diameter is not as much of a factor on RPM as is pitch. The 15-pitch stainless would have probably been the better choice.

 

[Navigator]

Another Prop Question

Since we seem to be in another round of Prop questions, I thought I'd add one too.<br /><br />I've got a 16 ft Aluminum Mod "V" Welded John boat with a 40 HP Honda. I've had a rash of bad luck over the last 2 years and I've destroyed 2 props (high speed prop strikes). Anyways, I started out with an 11 1/8 x 13 Alum prop which easily hit the redline with a lightly loaded boat. When it bought the farm, I replaced it with a 11x15 alum prop. It would bring me near the Redline when lightly loaded, but when I had a fully loaded boat, it barely made it to the recommended WOT range. When that one went to davie jone's locker, I figured I'd go back to the 13 but swith to Stainless. I ended up with a 10.5 x 13 Stainless. This prop now lets me hit the Redline even with a fully loaded boat. GPS Speed on both the 13's is still around 32 mph lightly loaded and 27 with full load.<br /><br />My question, should a 5/8" reduction in diameter cause me to get an additional 300 RPM or is it just the fact that the Stainless is much more efficient since the blade thickness is that much thinner. I'm now thinking I should have searched out a 15 in stainless?<br /><br />Anyone ever have this type of experience?<br /><br />Thanks,<br />Nav

 

[Dhadley]

Re: Another Prop Question

Youre not in a bad position though. You can send the 13 out to have some "bite" added. Whether they do it with additional cup or add a slight amount (1") of pitch. <br /><br />Youre much better off trying to improve efficiency on the 13 than to decrease efficiency on a 15.

 

[walleyehed]

Re: Another Prop Question

Stay with the 13...As Dhadley said, you can add some bite if needed, but don't give the 15 a second thought if thinking about reducing the pitch...It just doesn't work well going that route.

 

[Navigator]

Re: Another Prop Question

Any Idea as to where I can have some "bite" added to the prop. Maybe additional Cup or even have pitch changed up to 14?<br /><br />Nav

 

[Dhadley]

Re: Another Prop Question

Any decent prop shop can do it. Just take it to any marine dealer and they'll send it off for you. The prop shops usually stop in twice a week to dealers.