The DEEP DRILLER, at 60.0 feet draft in sea water, has VM = 974,441 foot-long tons, LM = 40,301 foot-long tons, TM = 3 foot-long tons, FSML = 30,572 foot-long tons, and FSMT = 18,732 foot-long tons. What is the uncorrected height of the center of gravity?
• Relationship between vertical moments (VM) and the height of center of gravity (KG) • Meaning of uncorrected KG versus KG corrected for free surface effect • Which of the listed values (VM, LM, TM, FSML, FSMT) actually enter the basic KG calculation
• Start by recalling the basic formula that links total vertical moment to KG when you already know the vessel’s displacement in long tons. • Ask yourself: does "uncorrected" KG include or exclude the free surface moments (FSML, FSMT)? Which terms should you leave out at this stage? • Think about which quantities are just moments and which are corrections applied after you have an initial KG.
• Be sure you are using only VM and the vessel’s displacement to get the uncorrected KG value. • Do not mix in free surface (FSML, FSMT) when finding the uncorrected KG; those are used later as corrections. • After you compute KG, check if the magnitude (around a few dozen feet above keel) is reasonable for a unit with a 60 ft draft.
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