Re: porpusing problem
 

What Wobble said. Try a couple props with more or less cup. Some dealerships will have "loaner props" for you to try before buying. Also try a 4 blade. Do the simple stuff first

Re: porpusing problem
 

Thankyou. I tried a 4 blade 22 pitch b1 and lost all my top end as a matter of fact I lost about 8mph, Man I was extremely bummed, the prop guy said he could cup it some more but really wasnt happy about that. With the 4 blade the boat did alot better it still hopped a little and came out of the like it was nobody business I called throttle up and they did not do the loaner program with 22 pitch props so again back to the old drawing board. thanks again guys

Re: porpusing problem
 

did you ck to see how much hook is there? I agree that most pleasuer boats have a little hook or rocker in the hull to make them user friendly.Having worked for a Baja dealer and driveing alot of them and seeing what they do to the bottoms it generaly inxs of what you want there for higher speed running. I have sean them be as much as over 2 inchs at the transom but only go forward 6 inchs :eek: . just my 2cts :cool:

Re: porpusing problem
 

When you lost your 8mph, did you lose rpm also? If your rpms were up near max, then you could try a 24p b1 to pick the speed back up.

Re: porpusing problem
 

swaaby, read this thread on the subject...good info in there.

Re: porpusing problem
 

HOOK And ROCKER
The bottom is referred to having a ”hook” if it is concave in the fore-and-aft direction. A hook causes more lift on the bottom near the transom and forces the bow to drop. This increases wetted surface and reduces boat speed. A hook, however, aids in planing and reduces any porpoising (rhythmical bouncing) tendency. A slight hook is often built in by the manufacturer. A hook also can be caused by incorrect trailering or storing the boat with support directly under the transom.

The opposite of a hook is a Rocker. The bottom is convex or bulged in a fore-and-aft direction. It can cause a boat to porpoise.

This from Mercury Racing Manual.

Re: porpusing problem
 

Now, Hydrolift has gotten to the point! "Hook" makes your boat plow, not porpoise. "Rocker" causes porpoise. The Mirage and Mirage+ props (what you run) are terrific "bow lifters", and that is NOT what you need. Try a known "stern lifting" prop (such as a Hydromotive O-IV) in your pitch range before messing with the hull. The folks at Throttle-Up can point you in the right direction if you can give them all the proper info. --- Jer

Re: porpusing problem
 

ECeptor, If I remember right I think I was maxed on RPM's. :drool:

Re: porpusing problem
 

jpclear, Thanks alot I will call them today with my specs again, The only thing is they do not have the prop program for a 22 pitch, However they said if I bought one they would exchange it for what I need. To me that is the same thing except you pay for it ?

Re: porpusing problem
 

Then try the 24p.