🔍 Key Concepts

• Vertical moments (ft-kips) and how they relate to a change in liquid weight in a tank • How to use the stability data booklet or loading manual table for drill water tank 23 on the Coastal Driller • The relationship: change in moment = weight removed × its vertical distance (VCG)

💭 Think About

• Look up the data for drill water tank 23 when full and when the level is reduced by 2.5 feet. What values in the table change? • When water is discharged, is the vertical moment increasing or decreasing, and by approximately how much compared to the full-tank moment? • Estimate the weight of 2.5 feet of drill water removed from that tank and combine it with the tank’s vertical center to approximate the change in vertical moment. Which choice is closest?

✅ Before You Answer

• Confirm you are using the correct density (specific weight) for drill water given in the problem or booklet, not fresh water unless specified • Verify you are using the incremental change (2.5 ft) in tank level, not the total tank height or total capacity • Double-check that you are reading the moment units (ft-kips) correctly from the tables and not confusing them with weight or volume units