re power

[pianewman]

Okay, now it's beginning to make sense to me. I thought I had been cured of the "Seacraft" addiction since 1989, when my dad sold his 1974 Tsunami. We wondered at the time why there were so many Seacraft owners that were adding trimtabs, as we found the concept unnecessary.
Fast forward to 2010. My dad, at 87, has a relapse, buys a 1973 20' CC, with a heavy Johnson, repowers with a 2008 Merc 150 (I think 450lbs. +), and we wonder why the aft of the boat sits so low in the water!
Thanks for the clarification. Now I know why the move toward trimtabs to assist getting on plane, etc.
Are the fins that attach to the cavitation plate of any value? Sure would be a lot less fuss than installing trimtabs.

Carl Moesly designed the 20' hull for the I-6 Merc, which weighed less than 300 lbs! Think about it. The further you go above that, the more you screw up the CG, which means the boat won't ride as well as designed, and your min planning speed will increase, which is a big deal if you plan to run offshore in rough seas. Also keep in mind that the SeaCraft hull is lighter, narrower and much more efficient than the average modern deep V, which means it doesn't NEED as much power as most modern 20' boats. The 20' hull will start to go airborne in seas over 3' at speeds over 20 kts, so unless you're into racing on flat water, a 150 is more than enough power for a 20 if you run offshore very much!