As I sat here many nights reading through this site (great site by the way) I have noticed many newbies so I don't feel too bad. I am new to boating this season. I got a good deal on a 19' Sunbird Cudy, I/O, 4.3l OMC set-up. Everything had been working great until I ran into something in Lake Erie. I know BIG shock someone ran into something in Lake Erie! I busted up the prop, it was a Michigan Wheel 011008 14.5X19. It ran good, I was running about 40mhp, at 4000rpm which was WOT, typically 2 adults 2 medium size kids. Not knowing what the manufacturers recomendation on WOT is I read through this site and found that a typical 4.3 should run 4500-4800 WOT. So I decided when I bought my new prop I would drop the pitch to get a little more RPM. I went to a Michigan Wheel Vortex prop 992003 15X17. I also decided on this size because there was a spare prop inside the boat (eaten up but usable) that was that size also but us was a P/N 387180 (I think was hard to read) but it was a 15X17.
So I take it out yesturday and the RPM went up over 5000! Close to 6000 at WOT! :/ Speed was only about 30 maybe 35... So I spent the ride crusing around 25MPH! I am confused that there was such a huge difference. Is the Vortex a much more efficent prop or did I calculate wrong or?....
Next thing is what prop do I try next?
So I take it out yesturday and the RPM went up over 5000! Close to 6000 at WOT! :/ Speed was only about 30 maybe 35... So I spent the ride crusing around 25MPH! I am confused that there was such a huge difference. Is the Vortex a much more efficent prop or did I calculate wrong or?....
Next thing is what prop do I try next?