The DEEP DRILLER is loaded as shown in the Sample Load form #3 (Preparing to Drill). If the liquid mud in mud pit #4 (see table 8) is dumped, what would be the new metacentric height corrected for longitudinal free surface effects?
• Metacentric height (GM) and how dumping a tank affects stability • How to apply free surface correction using the data from Table 8 and the Sample Load Form • Difference between initial GM and GM corrected for longitudinal free surface effects
• First, think about what happens to the vessel’s overall KG (center of gravity height) if you remove the weight of liquid mud from pit #4. Does KG go up, down, or stay the same? • Next, consider how the free surface effect from mud pit #4 contributes to the total free surface correction. If that tank is now empty (or pressed up), how does that change the free surface correction term? • After adjusting both KG and free surface correction, how will that change the corrected GM value compared to the original condition in Sample Load Form #3?
• Verify the original GM (uncorrected) and original GM corrected for longitudinal free surface from Sample Load Form #3 before any changes. • Use the correct moment to change KG formula for adding/removing a weight: ( , \Delta KG = \frac{w \times (dKG)}{\text{Displacement}} , ) and track the sign carefully. • Recalculate the total free surface correction with mud pit #4 empty and ensure you apply it in the right direction (subtracting from GM).
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