My 89 311 has 454 mags stock depth B1's ( 9000lbs)... I am running 24 Q IV's Top speed about 67-68 mph. While I can get to 5000rpm it takes some adjusting to get there. Seems to plane ok . Question is Porpoise'n problem ...If I am running WOT or maybe even over 60 mph I have no problem ....the Problem is at 35-55 mph "cruising" If drives are almost all the way in 1-2 it is ok but any attempt to trim up seems to bring on the bounce .... While I would like to go 68-70 all day ...not gona happen ...Main factor is Rev limiter poking me in the ribs... ....Just doesnt seem like efficent operation with the drives tucked under the boat .... What would be a happy median ?

Consider a round ear 4blade propeller that will leverage the stern more and carry the bow. The Q4's aren't holding the stern well enough.

That would be the easiest test. Also the CG could be too far forward or worse case scenario, bottom issues. Doubt the last one though since you carry well at all other speeds.

You just have a spot the props may not like.

I would agree with Brett, I think the Bravo I propeller may do very well on your boat. I was surprized to see that you are running the QIV's. Typically non-stepped hulls, perfrom better with round ear props.

Julie