IMCO or Sportmaster
 

I've been thinking about putting a shorty on my Fountain because I’m getting way to much slip (20%) and I'm thinking it's because my prop is to deep. I've been getting mixed reviews on whether to use the IMCO SC lower or Mercuiser Sportmaster lower and how short I should go. To give you a little history, my 2006 29 Fever originally came with a Merc 525 with a standard length Bravo 1XR. I've since replaced the 525 with and Ilmor 625 which is about 300 pound lighter than the 525 and I replaced the XR with a standard length IMCO SC. My X dimension from the factory was at 19 inches which I believe puts my prop shaft about 4 inches below the hull. I’m still kind of new to performance boating so any input would be helpful.

http://i1215.photobucket.com/albums/...o/IMG_0271.jpg

http://i1215.photobucket.com/albums/...o/IMG_0270.jpg

If you decide on a Sportmaster -2, I have one over in the classifieds.
http://www.offshoreonly.com/forums/s...-only-acc.html

A deep prop would cause less slip not more. Your bad slip number is probably coming from raising your drive way up to get more rpm. A shorty will get you some more mph for sure and you will need to re prop probably. They increase slip by reducing the drag on the prop by bringing it closer to the surface.
Better to test your slip by running drive neutral and getting your numbers from there. I would def try the shorty I picked up 5 mph and better handling.

Bravo 1 props are typically about 1" less than stated. Did you take that in consideration calculating your slip?

Try a different prop.
When I had 4 blade clever style hydromotives, I had 28% SLIP at cruise 3500rpm. When I went to 5 blade Maximus, I had 13% SLIP at cruise.

At 25 it's still at 18% slip.

update to this thread?

+1 on prop selection