motor hight
 

I know this is been road to death, but I just want some thing to show my dealer so he gets the idea. The boat is a 20 SF 1979 Redon with 25 in. trans. I carry 50 gal. fuel , 4 crew, & gear. I am installing a F115 Yamaha . Please tell me how the motor needs to be. If more info. is needed let me know. Thanks PS. it has a Birdsall T top.

These hulls seem to like the ventilation plate 1 1/2" above the bottom of the transom. When I first got my 18 it was about an inch and half below the transom. Moving it up made a huge difference and now the boat runs as it should.
Rod

Rod is right on! Have the dealer place a straight edge along the bottom of the keel out to the cavatation plate with the plate and straight edge parallel. The 1 1/2" number is a good start. My engine was 3/8" above and was a dog spraying water everywhere, I installed a 6" manual jack plate and moved the plate to almost 3" above the keel, major performance improvement. Good luck.

My 20 is at highest setting At least 1 1/2" high

Thanks to all , very helpful. Fritz