74’ Seacraft 23 CC Rebuild

[Capt Terry]

Sorry I am responding at a disadvantage from only my cell phone while out of town. I would expect the combined CG of your 900 lb inboard and outdrive to be several inches to a foot forward of your transom. Bushwacker’s CG moved about a foot aft when he moved his ETEC 150 from his transom to a Hermco bracket. Therefore when you put two ETEC 150s on a bracket I would expect a bigger change than the 1.15’ you quoted. My 20” G1 ETEC 150 weighs 418 lb. The G2 must weigh more than that with power steering.
I agree with those recommending a large single instead of twins which I suppose opens up more space on the bracket for climbing onto when in the water.
The bracket floatation will not help your CG when underway.

[Glosta23]

Capt. Terry -

Checked my math again, and my distances from transom measurements and things seem accurate. Double checked ETEC weight as listed on Evinrude spec sheet and confirmed weight of my old engine and outdrive. Things look good.

Also received quote from Armstrong. Bracket weighs approx. 170 lbs and setback will be 30" not 36", so that should help me a little bit as well.

All interesting stuff to play around with in the hopes of getting the correct CG before actually bolting anything to the boat!! Fingers crossed...

[Capt Terry]

Looks like you probably did it correctly. I will examine it again next week when I am home. And you may tinker with the calc more as you have other items to consider to minimize the cg change. Best wishes.