[MHml] Stern shape

[Allied]

I have been adding 700 mm and deepening my sterns (changing transom, for 
boarding platform) and I am about to glass over the foam I have added. I 
have shaped the sterns to be square (port to starboard), at the end of the 
boarding platforms, but I have a 500 mm radius, forward to aft, going down 
to the almost flat bottom of the hulls. No one has commented on this until a 
friend saw it last week and he said that was not good and I should have a 
flat, or even slopping the opposite way to my radius small transom, to give 
the best (least) drag through the water. Help please!

Colin