I've got a longshaft Nissan 40 TLDI 2-stroke. The motor ventilates at anything above bare planing speed. The problem seems to be affected by weight and weight distribution but not in a simple way. I'm assuming that load and load distribution are levering the planing attitude around - given the high amount of flotation around the periphery of the hull - affecting the bite of the motor. The motor is trimmed down all the way, and the ventilation plate is right about at the transom bottom. Short of notching the transom, any suggestions what to try? I've tried both cupped and uncupped alum props. Would a fin of some sort help? They seem to come in a variety of sizes.