The liquid mud tanks on your vessel measure 30'L by 15'B by 6'D. The vessel's displacement is 968 T and the specific gravity of the mud is 1.8. What is the reduction in GM due to a pair of these tanks (p/s) being slack?

Correct Answer: Option D — .87 foot

Free surface moments generated by slack P/S tanks degrade ship stability. Applying the standard fluid transfer formula using tank geometry (30' × 15' × 6') and 1.8 SG mud divided by 968 tons displacement computes a virtual center of gravity rise and a 0.87-foot reduction in GM.