Hi Mike, Does the comple building board have to change, or the top 1/4 inch where the cut out section is rubber cemented for ct out, for me I would just like to do it right and get the new top cut out plan, and not modify the keel drrawings as happens many time to us intermediate modelers the easier fix does not work most of the times better just a revised top sheet the 1/4 inch plywood to rubber cement the cut out pattern too,, just my opion. Don Farr