On a vessel of 34,000 tons displacement, a tank 80 ft. long, 60 ft. wide and 30 ft. deep is half filled with fresh water (SG 1.000) while the vessel is floating in saltwater (SG 1.026). What is the free surface constant for this tank?

Correct Answer: Option C — 40100

Free surface constant is determined by multiplying the uncorrected inertia moment (length times breadth cubed over twelve) by the specific gravity ratio of the fluid to saltwater (1.000 / 1.026). For an 80x60x30 ft tank, this results in 40100.