After Marking Datum Line on the plan, next is to figure where to put the JIG....

Since the Jig Board is 3 1/2" wide - selected 5" from the keel to give me ample spaces to cut the slots for the bulkheads. (Pic 1)

Using the Jig Board itself and line it up with the Jig line that I just made to mark the top of the Jig on the plan. (Pic 2)

Plan showing three lines to use as reference point on building Jig, Bottom line is Keel line (Datum), Middle line is top of the Jig, Top line is bottom of the Jig. (Pic 3)

Last check to see if the Jig is acceptable before cutting the Jig Board. Placed Keel and Bulkhead #3 and #8 on the plan. (Pic 4)

Looks good to me so far...