Modified V-bottom, prop recommendations!

MartinH2 · Jul 11, 2014

I have a 29' Cobra Performance 290SXT (4400lbs) modified V a with Mercury 525, Bravo One XR 1.5:1, and Bravo 1 28P propeller. Originally with the Bravo 1 bouncing off the rev-limiter at 5400rpm I could achieve 89-91mph depending on cargo. I purchased a 5 blade 28P Mercury Maximus (15 5/8 diameter) in efforts to achieve better hole shot and all around performance. With the Maximus I can only reach 78mph at 4900rpm. In order to gain open throttle 5200-5400rmp and regain top end, should I drop to a 26P Maximus or go back to the Bravo? What would a change in diameter (decrease to 15 1/4) do?

HALLETT BOY · Jul 20, 2014

You can have the Maximus turned down a little , that should do it . I had my diameter trimmed down to 15 1/4 I think . A good prop shop should be able to help you.

skav · Jul 20, 2014

MartinH2 said:
View attachment 350762

I have a 29' Cobra Performance 290SXT (4400lbs) modified V a with Mercury 525, Bravo One XR 1.5:1, and Bravo 1 28P propeller. Originally with the Bravo 1 bouncing off the rev-limiter at 5400rpm I could achieve 89-91mph depending on cargo. I purchased a 5 blade 28P Mercury Maximus (15 5/8 diameter) in efforts to achieve better hole shot and all around performance. With the Maximus I can only reach 78mph at 4900rpm. In order to gain open throttle 5200-5400rmp and regain top end, should I drop to a 26P Maximus or go back to the Bravo? What would a change in diameter (decrease to 15 1/4) do?

I would have gone w a 26p 15 1/4" factory labbed Maximus. The 15 5/8" Maximus is not labbed.

Did you check your slip w the B1? The 28p B1 was slipping a lot more than the Maximus, which is why you were gutting the limiter.

HavaToon · Jul 21, 2014

Trade it out for the brand new Pro Finish Maximus ST.

http://www.mercuryracing.com/blog/new-props-for-summer/

BigSteve · Jul 21, 2014

Its really hard to say what prop will work best, without doing more on water testing

Putting together data on how different props react on your boat is key

The Wizard has been doing his homework, filling it with important data.

Taking notes on hole shot time to plane, how does the boat carry itself at cruse to wfo,including the trim setting, overall control and wfo.

Brent over at BBlades might have a couple props for you to try, the more baseline #s you have to work with, the better the ability to contrast effects of differing prop geometry on your hull.

Modified V-bottom, prop recommendations!

MartinH2

Member

HALLETT BOY

Well-Known Member

skav

Well-Known Member

HavaToon

Well-Known Member

BigSteve

Well-Known Member