The SS AMERICAN MARINER arrived in port with drafts of: FWD 28'-04", AFT 29'- 10". Cargo was loaded and discharged as indicated in table ST-0102 below. Use sheet 2 in the white pages of the Stability Data Reference Book to determine the final drafts.
Discharge 240 tons---155 feet fwd of amidships Discharge 160 tons---38 feet fwd of amidships Load 115 tons---35 feet aft of amidships Discharge 170 tons---205 feet aft of amidships
• Use moments about amidships: weight (tons) × distance (feet) and keep careful track of forward vs aft signs. • Relate the total trimming moment to the change in trim using the vessel’s MT1" (moment to change trim 1 inch) from Sheet 2 of the Stability Data Reference Book. • Once you know the total change in trim, split it between the bow and stern according to the vessel’s length between perpendiculars (LBP) to find individual draft changes.
• For each load/discharge, should the trimming moment tend to push the bow down or up? How will that affect the forward draft? • After summing all trimming moments, is the ship finally trimmed more by the bow, more by the stern, or closer to even? How does that guide which answer choices are possible? • When you distribute the change in trim between the ends, how do you calculate how many inches the forward draft and aft draft each change from the original condition?
• Be consistent with signs: choose forward moments as plus and aft as minus (or the reverse) and stick with it for all four weights. • Verify you are using the correct MT1" and LBP values from Sheet 2 for the SS AMERICAN MARINER, not a different vessel or sheet. • Before picking an option, add your computed draft changes to the original drafts (FWD 28'-04", AFT 29'-10") and check that the difference between FWD and AFT drafts matches your calculated final trim.
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