chage in power

[boating dave]

Hello,
what I am having a proublem with is my 1980 chris craft, there was a single engine inboard at one time and someone changed it to a in/out board. what I am having a hard time with is that when I get it up on plane it rolls side to side and will not stay flat over 20 knots. I was told that is has to do with the shape of the hull, because it was designed for an inboard. what I am doing is trying to find out a little info about it and maybe try to play with the bottom a little. I can build just about anything but have no ideal about hulls. If anyone has any advase I would really apreciate it. thanks
Dave

[gonzo]

Sounds like dynamic instability. How do you know the boat didn't always do that?

[boating dave]

I am not sure if it always did that or not to tell you the truth, anyone out there every have a 1980 chriscraft 26 express before that knows

[gonzo]

If it was originally an inboard, the hull is designed for a Center of Gravity much more forward. The easiest solution is to go back to the original design. It is possible to modifiy a hull, but more expensive than a new one.

[cyclops]

How did you get the sterndrive boat to balance at a somewhat normal waterline without putting 1500#-2000# of ballast where the old engine sat or less further up in the bow?