Frizz, you have a very interesting problem; wish I had the technical skills to answer, but I think Blue Heron does.
You are going to like 400 hp. Mine is 300 and I'd like a bit more.
CG and roll is the big issues. If you know the weight of the new engines(and bracket?) and how far back from the transom they will be, Dave can calculate the for and aft CG effects. Putting in a water ballast should be able to remedy any issues fore and aft and he should be able to calculate the ballast needed, as well. Vertical CG might be tougher, especially since the engine weight will be both higher and farther outboard than an I/0. Still, having a bunch of water weight low in the bow will help the vertical CG, damping down the roll. How all that will play out in the real world might be pretty different from what the calculations say, just have to try it.
The worst possible result would be for the boat to develop a snap roll. Mine rolls, (how could it be otherwise?), but it doesn't snap. A friend of mine owned one years ago with twin outboards, and a hard top and a tower (I kid you not). It had a viscous snap on top of a extremely wide roll, even after they took the tower off. His wife, who was a pretty good boater, refused to set foot on the boat after her first experience.
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11-30-2014, 08:50 PM
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