What is the change in longitudinal moments for the Coastal Driller if 2.0 feet of drill water is transferred from a full drill water tank 23 to an empty drill water tank 6?

Correct Answer: Option B — 7,990 foot-kips decrease

Shifting liquid weight longitudinally changes the vessel's trim moment. Transferring 2.0 feet from tank 23 to tank 6 moves weight forward, decreasing the overall longitudinal moment by 7,990 foot-kips according to the specific vessel's hydrostatic and tank capacity particulars.