You are on a Mariner class cargo vessel. Your drafts are: FWD 26'-06", AFT 28'-02". You wish to increase the calculated GM of 2.7' to 2.9'. What tanks should you ballast? (Use the white pages in the Stability Data Reference Book.)
• Metacentric height (GM) and how adding weight low in the ship affects stability • Using the white pages stability tables for the Mariner class to see each tank’s effect on GM for a given displacement/trim • The difference between forward and after double bottoms (DB) and deep tanks (DT) on GM and trim
• Based on the given drafts, estimate the vessel’s displacement/trim in the Stability Data Reference Book, then find the table that lists how filling each tank changes GM. • Compare how much each listed tank (DB1, DB2, DT1, DT6) changes GM at that displacement. Which combination gets you closest to an increase of about 0.2 feet in GM? • Think about whether adding ballast forward or aft will significantly change trim and whether that matters for the GM change requested in the question.
• Identify the correct displacement and trim page in the white pages that matches (or is closest to) FWD 26'-06" and AFT 28'-02". • Verify the ΔGM (change in GM) values for each candidate tank on that page; add the effects for combinations listed in each answer choice. • Confirm that the selected combination both increases GM (not decreases it) and gives a total ΔGM closest to +0.2' without relying on tanks not listed in the choices.
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