162. On a vessel of 12,000 tons displacement, a tank 60 feet long, 50 feet wide, and 20 feet deep is half filled with fresh water (SG 1.000) while the vessel is floating in saltwater (SG 1.026) What is the reduction in metacentric height due to free surface?

The free-surface correction, calculated as the density ratio of fresh water to saltwater multiplied by the second moment of area divided by the underwater volume, is 1.44 ft. This reduction in metacentric height is determined by the tank's dimensions and the density difference, not the fill level.