My 1997 Baja i92 islander runs great at speed but between 25-40 mph the boat sometimes porpoises despite adjusting the trim.The problem increases the more people in the boat and the only way out of this is to accelerate past 40 (not ideal when towing a skier). The boat has a Merc 5.7 LX and Alpha 1 drive. I run 21" Mirage & Laser 2 props.
I have seen alloy/stainless cavitation plate extentions (would this help?)while on vacation in Florida but stuff like that is in limited supply here in the UK.
All help appreciated.
David