The SS AMERICAN MARINER arrived in port with drafts of: FWD 21'-10.6", AFT 22'-11.6". Cargo was loaded and discharged as indicated in table ST-0089 below. Use sheet 2 in the white pages of The Stability Data Reference Book to determine the final drafts.
Discharge 280 tons--200 ft fwd of amidships Load 150 tons--150 ft fwd of amidships Load 150 tons--100 ft fwd of amidships Discharge 90 tons--247 ft aft of amidships
• Use the total weight change to find how much the ship’s mean draft will change (use TPI or tons per inch immersion from the reference sheet). • Use trimming moments: (weight) × (distance from amidships) to find the total trimming moment and then use MT1" (moment to change trim 1 inch). • Remember that distance forward of amidships creates a trimming moment by the bow, and distance aft of amidships creates a trimming moment by the stern.
• Is the ship’s total displacement increasing or decreasing after all loadings/discharges, and should that make the mean draft go deeper or lighter? • When you sum all the trimming moments (bow and stern), is the ship trimming more by the bow or by the stern compared to the initial condition? • After you find the change in mean draft and the change in trim, are you correctly splitting the trim change between the forward and aft drafts using the LCF/LCB guidance from the reference sheet?
• Double‑check the signs of each operation: discharges reduce displacement, loads increase it; distances forward/ aft of amidships must be treated with correct +/‑ convention. • Confirm you are using the correct TPI and MT1" values for the initial mean draft from sheet 2 of the Stability Data Reference Book. • After calculating new drafts, verify that FWD + AFT divided by 2 equals the new mean draft within a small rounding tolerance.
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