I have a 1987 Stratos VT180 Ski (VT Rocket) and just replaced the Mariner 150 that it came with a 200 HP EFI Merc. Pushing it with a 24 pitch trophy 4 blade SS prop. I mounted the Merc on the same hole pattern and vertical position on the 4" jackplate, but the boat porpoises almost continually at most any speed short of wide open in anything but totally smooth water. The center of the prop shaft appears to be about 3" beneath the bottom of the keel. I tried jacking the motor up higher on the jackplate but ran out of adjustment room. At that point the center of the prop shaft was just about level with the bottom of the keel.
Any suggestions?:confused: