The liquid mud tanks on your vessel measure 18'L by 10'B by 6'D. The vessel's displacement is 944 T and the specific gravity of the mud is 1.9. What is the reduction in GM due to 2 of the tanks being slack?

Correct Answer: Option B — .16 foot

The moment of inertia of a rectangular tank's free surface area is proportional to length times breadth cubed. For two small mud tanks measuring 18'x10' with 1.9 SG mud on a 944 T vessel, the resulting metacentric height reduction is 0.16 foot.