docmanrich37

What do I need to do to my props to get less slip.I'm running 1.30 bmaxs and turning a semi worked 28s 4 blade mercs.I'm going to try a new set of 26s.Tried a set of 26 test props that looked used and worked and all i got was 200 more rpms and no speed.It looks like i have 19 % slip when putting the #s in the calulator.Should I try a set of merc 5 blades like 26s or something.Herrings are out of the ? wife would kill me.unless someone has a set just laying around that needed demoed.28s are turning about 54-5500 rpms and the 26s where turning a few more.

zt260

5 blades should reduce the slip by about 5%. Just remember slip isn't always a bad thing. How deep is the propshaft?

docmanrich37

I think it was 5 1/2" from the bottom.

throttleup

If you use 25 instead of 26 for the pitch your slip drops to 15%. That's on the high end of where you should be. 25 is a more accurate pitch for 26 Bravo 1's than 26.

Any issues getting on plane?
Is there a rooster tail? How high?
Do you need to use a lot of positive drive trim on the drives to get max speed?

docmanrich37

It looks like i need to turn a set of 28/27 5600rpms and be at 12% slip to get to 96.7 mph.Would like to turn it upto 58 rpms.
Having no issues getting on plane at all.
There is a rooster tail about 3'-4' tall when i trim up about halfway.
Postive trim i think i'm fine but i'll have too check when i go to FL next month.

Kidnova

Not to hijack doc's thread, but what does needing allot of positive trim to get max speed "say" about the prop ? Mine seems to be just that way....likes lots of pos trim.

Thanks

throttleup

Excessive positive trim, amoung other factors, may indicate the drive is mounted too high.

When a drive is too high it's common to have to trim higher than normal in an attempt to get the bow up. The deeper the drive the greater the leverage it has to lift the bow. As the drive is raised this leverage decreases and excessive positive drive trim is commonly used. This can lead to a rooster tail.