Howard --
FYI - the transom is flat, not curved. It appears to be bowed from the plan view(s) because the top of the transom is curved and it is angled with the bottom of the transom further forward than the top (see side view). Because of this angle, in the plan views(s) the top of the transom is farther aft than the outside edges giving the impression that the transom is bowed. This visual is only the result of the CAD.
Bill