The plan says "cut the upper portion of bulkhead No 2 and fit that section last". I forgot to trim the bulkhead and realised it only now. the reason for leaving the section empty initially is to allow the beam to come in and be fitted.
So now it is the difficult task of "destroying" part of the bulkhead !
Finally this is how it should be. as I go along I find bits of mistakes here and there...nothing major yet so far . I am sure if I ever build another boat I would know how to read and interpret the plans more accurately!