Sport hydro turning issues

[bigriggr]

Here's what I got, need your advice.... An old 40" glass Claim Jumper sport hydro, w/stock OPS 67 and an Irwin pipe. Fun boat to run but cannot get it to turn under full throttle. Had no turn fin when I got this boat, have tried straight fins, angled fins and even have had no luck with this Top Secret cupped fin. I've tried light, to heavy positve angle's to try to cup the water agressively, but I still have to back off to half throttle in order to turn, then she turns fine. Anything more than half throttle the right front sponson lifts very high and you loose all and any speed you had, and it washes way out of the turn. OR, it is hopping the front sponsons around the corner, and I have to back the throttle off to lay it flat again. I've also been trying slight to heavy negative (I'd say 1 to 5 degrees) on the strut hoping to push the front end down.

Another issue is cannot hammer the throttle or the boat will swerve to the right drastically, have to ease the throttle to full then she's fine.

Any advice would be appreciated,

Bill