Where are pieces 5b on creatology aircraft carrier?

5B refers to the central notch in the keel of the ship which is the long diagonal piece on the first sheet of wood and 5B refers to the notch in the end of the first bulkhead. This is the piece directly below the keel on sheet one that looks a little like home plate and also contains notches 40,42,46, 47,49,50, 57, slot 6, and tab154.