Braket build

[martin]

Calculating bouyancy and size of bracket with 30" set back and getting something like 525lbs of boyancygive or take.. But with moter and 40 gallon livewellabout 12" in front of transom.. I am negative about 475... I do have trim tabs.. Shoukd i build bracket with max lift and then start placing tank console and coffin box in... Or maybe put some weights in the hull and see where things need to be.. Thanks for the reply bushwacker

[Bushwacker]

The flotation at rest isn't nearly as important as balance and performance up on plane. When you're up on plane with the tank out of the water, the boat will still know you shifted it's CG aft by about 18" or so! A 40 gallon livewell near the transom doesn't help either. I'd suggest putting it forward of the CC.

When I repowered from a 300 lb motor on the transom to a ~420 lb motor sitting 30" further back, my min planing speed went from 12-13 mph to the low 20's and that's with trim tabs! And the Seafari has more weight forward than the CC to begin with. I finally got it back down to 12-13 mph by going to a 4B prop and a fin. Don't know how fast you want to run or what sort of seas you run in, but if you're running offshore in seas of 3' or so, 120 hp is plenty of power for a 20. Ran mine for over 30 years with a 1975 "115" (crankshaft hp) that really only put out about 90 hp at the prop. Cruise speed on Bahama trips with very heavy load was about 20 kts, but it rode very well and I could hold that speed in seas up to about 3'. I couldn't use much more power in those conditions, so you might want to try it with the 120 first!