The SS AMERICAN MARINER has drafts of: FWD 15'-06", AFT 18'-06". Use the white pages of the Stability Data Reference Book to determine the drafts if you ballast the forepeak with 62 tons of seawater.
• Trim and draft change due to added weight in the forepeak on a vessel with known hydrostatic data • Using the Stability Data Reference Book (white pages) for the SS AMERICAN MARINER to find the trimming effects per ton at the forward and after perpendiculars • Converting tons of ballast into a draft change at the forward and aft drafts
• How does adding weight at the extreme forward end (forepeak) affect the forward draft compared to the after draft? Should the bow go deeper or shallower? • When you consult the white pages, what specific table or column tells you the change in trim per ton and how do you use the vessel’s length to distribute that trim between FWD and AFT? • After finding the total trim change, how do you split it into a change at the bow and stern to get the new drafts, starting from 15'-06" FWD and 18'-06" AFT?
• Be sure you are using the correct displacement/trim data for the ship’s present condition (near the current mean draft/displacement). • Double-check your signs: is the trim change by the bow (forward going down) or by the stern (aft going down)? • After calculating the new drafts, confirm that the mean draft change is consistent with adding 62 tons (i.e., the average of the new FWD and AFT drafts should reflect the added displacement).
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