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Shine, In my case, a 79 jackshafted diesel that has been converted to a closed transom bracketed outboard) I have no reference to what existed before and where the cg of the boat should be.
My question is how did you design your boat and where did you find the information to arrive at your calculations?
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Please understand below is an approximate way to do this....
If you moving weights around and you want to get the boat to sit
close to her original lines, then you can make a simple spreadsheet of moments (length of arm x weight of object). You have to make 2 columns, one with the weights and locations of an original boat's major parts, and the second column will be the new boat with proposed weights/locations.
The "measure from" location, needs to be the same on each boat (not always easy to do since thicknesses and layouts are different, but using the outside of the transom is a good place becasue its the same). Its not so important where you measure from, but it is important that the be the same spot on each boat. So you will have distances from that spot (+ numbers forward, - numbers to the rear) and the weight of the object multiplied together. The sum of all these numbers should be close to matching on each boat. Weights are measured from their center (center of gas tank, or center of baitwell, center of motor,etc.
In my case, I found a person who had a 23CC with motor mounted on the transom and big bait well in the floor. My boat is set up very differently, but floats right where it should.
Of course this really only works if you keep the total weight of the new boat close to that of the original. If you changing the weight dramatically, then you will need to find the CG and go from there
Joel