🔍 Key Concepts

• Use the Coastal Driller stability data (the drill water capacity and transverse moment for tank 23) • Understand how to compute change in transverse moments when fluid is removed from a tank • Relationship: Change in moment = (Moment per foot of liquid) × (Change in liquid height), with correct sign

💭 Think About

• Locate tank 23 in the drill water section of the stability booklet: what is the transverse moment for a full tank and the increment per foot? • Determine whether discharging (removing) drill water will create a positive or negative change in the transverse moment based on the tank’s location relative to centerline • Calculate the total change for 2.5 feet of water and compare your value’s magnitude and sign with the answer choices

✅ Before You Answer

• Verify you are using the correct tank (23) and the correct table/column for transverse moments, not longitudinal • Check that your units match the answers (ft-kips) and that you multiplied by 2.5 feet, not by the total tank depth • Confirm the sign convention: moments to one side of centerline are positive, the other side negative, and discharging water reverses the sign of the change compared to adding water