but I'll give it a try.. is your bulk head 1 piece all the way across the boat or 2 pieces starboard and port with a companion way to the forward end? if two this will work easier but it can be done on a one piece also...temporarally fasten a 1x6 vertically from the keel to the cabin top in the same place the bulkhead goes. then sharpen the end of a 1x2 stick that is a little longer than half the beam of the boat at the bulkhead location..now lay the pointed stick across the 2x6 and place the pointed end against the hull. draw a line on the 2x6 where the 1x2 crosses it and put a mark on the 1x2 where it intersects the edge of the 1x6.. and label them both 1.. move down the hull and 1x6 about an inch and repeat the process and label it 2. keep doing this until you have gone down to the keel.. you can now remove the 1x6 and transfer the tic marks to a sheet of plywood (or cardboard if you dont trust yourself the first time).. anyway I hope you get the process, it really works well and it is easy to do...