I had the same problem. The main cause is that monster overlapping jib. The comments I am giving were based on me trying to run a windward leeward course against A-Class cats. We had changed from a reach dominated course because nothing could touch the 6.0NA. When the A's showed up, I really regretted that.

1) Watch for the jib back winding the main. When you see it ease off. Back winding you can't really see hurts. Try adding a tell tail to the main ~ 1/3 of the jib height up and 12-18 inch aft of the mast.

2) Jib sheeting position is important. Start with the track centered and the traveler about 3 inches from the inside of the hull. Move it about an inch out for heavy air and a 1/2 inch in for light air. This is a starting point, find out what your sails like. Sheeting the jib properly is important. Sheeting it board flat all the time, will not cut it. If in doubt, ease the jib a little.

3) You don't have a boom. Some of the comments from H20 sailors can hurt you. Talk to 6.0 and 5.8 skippers. You are basically pulling down on the leach and depending on the cut of the sail to set the draft. IF you sheet too hard, you can hook the leach. You can try moving the mainsail traveler forward 1/2 inch and sheeting HARD with both hands. Get someone to take photos from behind.

4) Try using your mast rotation inducer as a rotation limiter. (This is tricky, with the rotation inducer, you must release and reset the inducer every time you tack. If you forget you can break your mast.) If it helps you can put a real rotation limiter on. Basically you want to limit the rotation to the centerline of the mast pointing at the shroud (the H20 sailors can help you with this).

If all else fails, fall off and point with the Tornado's. We love to watch the 6.0's trying hold the boat down when the wind picks up. If you see me trying to point too high, kick me hard when we get back to the beach.