A real puzzler. I've sailed the 39 and 46, but never heard of this before. What could be causing your main to overpower that big
genoa? Does this happen on all points of sail? I would check the tensions on the standing
rigging, and especially the forestay. If slack, might it be allowing the
mast (and both sails) to rake aft, say on close reaches or beats? Perhaps a consultion with a rigger might help. You have a great
boat. Good luck.