Your vessel's drafts are: FWD 19'-03", AFT 21'-03". The LCG of the forepeak is 200 feet forward of amidships. How many tons of ballast must be pumped into the forepeak in order to have a drag of 1 foot? (Use the reference material in Section 1, the blue pages, of the Stability Data Reference Book)
• Trim and drag: understanding how change in trim affects forward and aft drafts • LCG (Longitudinal Center of Gravity) and its distance from amidships for added ballast • Using the Moment to Change Trim 1 Inch (MCT 1”) or similar data from the Stability Data Reference Book
• How does adding weight at a known distance from amidships create a trimming moment, and how is that related to the desired change in trim (1 foot)? • What reference value from the blue pages links a trimming moment (ton-feet) to a change in trim per inch or per foot? • Once you know the trimming moment required for 1 foot of drag, how do you convert that into the tons of ballast needed at the forepeak LCG?
• Identify the correct MCT (Moment to Change Trim) value from the Stability Data Reference Book for the displacement/condition closest to this problem • Convert drag of 1 foot into inches of trim and verify whether it means the stern draft is 1 foot more than the bow draft, or a 1-foot change from the current condition • Use the correct lever arm (distance in feet from amidships to the forepeak LCG) when calculating the trimming moment: Moment = Weight × Distance
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