🔍 Key Concepts

• Free surface effect and how it changes when a tank goes from slack to empty • How the longitudinal free surface correction (FSC) is read or calculated from the DEEP DRILLER load form • Difference between FS moment of individual tanks vs. the combined correction applied to LCG/trim

💭 Think About

• Look at which tanks contain liquid mud on Sample Load Form #4 and note their dimensions and locations. How does dumping these liquids change the total longitudinal free surface moment? • When tanks are emptied, do they still contribute a free surface moment? Or is that contribution removed completely? How does that affect the total correction value compared with the original condition? • Compare the size and position of the mud tanks to other tanks that still contain liquids. Would removing the mud’s free surface increase or decrease the overall longitudinal FSC, and by roughly how much?

✅ Before You Answer

• Verify on the load form which specific tanks are designated as liquid mud tanks and whether they are slack, full, or empty before and after dumping • Check the table or column that lists longitudinal free surface moments (or equivalent) and recalculate the total after setting the mud tanks’ contents to zero • Confirm how the load form converts total free surface moment into feet of longitudinal correction, and apply that same method to the new total to pick the closest answer