The minimum freeboard in summer for a type B vessel that is 79 ft. or more but less than 500 ft. in length and has enclosed superstructures with an effective length of 25 percent or less of the length of the vessel must be increased by -
0.03 (500 - L) (0.25 - E/L) inches
where:
(L) = length of vessel in feet;
(E) = effective length of superstructure in feet as defined in § 45.59.