Humm….. this gets more curious as time goes on.
Just taken the published plan out of the magazine and found that the hull side pieces are infact the correct size. Clearly the magazine employs a very skilled designer to redraw plans for publication and correct any mistakes in the original draft.
Ah!……. I now have the answer. The second bulkhead should be glued to the hull base ahead of the 1/4″ square cross piece. The published plans show it behind this cross piece which accounts for the 1/2″ apparently missing. My original draft did show the correct bulkhead position but was not perhaps as clear as it might have been.
The answer to your problem is to remove the second bulkhead. I guess it is firmly glued in place so cutting it off at the level of the cross piece might be the best thing to do. Then make another bulkhead and glue it ahead of the cross piece.
Sorry about this problem, I promise to check and double check all the damn lines on my next plan.
Glynn Guest