I made my first try at casting an IOM bulb today with pretty fair results. Now I need to find the center of gravity, the way I understand it the mass in front of the CG is the same as the mass in back of the CG. In other words if I was to take the bulb and balance it on the edge of a knife the point where it balances is the CG. Am I right or wrong. If I'm wrong let me know the right way to find the CG

Army Dad ,
You're right. Depending on the shape, the 'curve' of the bulb, another way is just sit it on a flat surface. Where it rests is the CG. Is that exact? Not by a long shot, but it's usually close enough, sort of.
- 'Doc

The error in estimating the center of boyancy for the boat will probably be way worse than that for estimating your keel weight, but if you want to get more precise, you can do it by hanging the bulb and a plumb bob from the same point... the CG is on the line defined by the plumb bob and for a symmetrical bulb, It's right where that line crosses the bulb's line of symmetry.

You will never balance it on a edge knife edge.
The easiest way is to hang it like a plum bob. Move the string back and forth until it balances level.

Don M.