i need some help i have a bernico with a 125 optimax, when i first bolted the engine on the transom the cav plate was between 3 4 inches above the bottom of the boat which i thought was pefect, i took it out and when i hit 60 ish mph it starts to cavitave just for a second then grips again it does it over and over again the boat will slip to the left at the back when its happening, so i thought i would put a jack plate on with a 6inch setback to give the prop abit more grip bit it still does it, im running a 23 laser iv had a 4 blade trophy on and makes no differance, has anyone got any ideas on this what i can try ?