18" four blade to a 17" three blade using I boats exchange program

[JJB]

I have posted a few messages on this topic and wanted to get input on this before acting on it . I think I am going to use I boats exchange program with a solas 17" ss prop . I am trying to gain 300 to 400 rpms . I now have 18" four blade apollo ss giving me 5100 rpms from what i been told on here I will gain maybe 200 rpms by dropping a blade and also gain 200 by reducing my pitch to 17 " am I understanding this correct ? are solas with rubber hubs a good ss prop ? Thanks for all the help on this !

 

[Silvertip]

Re: 18" four blade to a 17" three blade using I boats exchange program

That's generally the way it goes. What engine and boat are we talking about? Before swapping the prop, why not experiment with engine height to maximize the setup. You may find that picks some RPM. Don't go so high that you lose water pressure or experience blow out with minor trim adjustment. Once setup is correct, then if you still need more revs, you can drop pitch with either the four blade or by going to the three.

 

[Dhadley]

Re: 18" four blade to a 17" three blade using I boats exchange program

Heed Siler's advise. Dropping pitch to gain top rpm is always a last (very last) resort. It almost always results in less efficiency.