单项选择题 （）measured at midship section and taken from inside the ship’s shell on one side to inside the ship’s side shell on the other side.

单项选择题 （）measured at the midship section and taken from outside of the ship’s side shell plating on one side to the outside of ship’side shell plating on the other side.

单项选择题 （）is a point midway between the forward and the after perpendicular.