I doubt that they would be interested in your turn fin.
Check to see that the turn fin is straight to the sponson sides, or ride pads, if you use them. Often a "bent" boat will hook badly from 2 surfaces conflicting with each other.
i'm trying to figure the optimum turn fin placement, and i know that if it's either to far forward or backward it will hook. i just can't remember which way will cause this...
i'll start with the fin trailing edge just forward of the cg.
from Advanced boat modeler turn fin should be jus ahea of CG if its to far forward then it will spin out and if it is to far back it will need more rudder to turn. Scott