🔍 Key Concepts

• Trim and draft change due to longitudinal weight shifts (using tons-per-inch immersion and trimming moment per inch/centimeter from the blue pages) • How to find the resultant trimming moment from multiple weights located forward and aft of amidships • Difference between mean draft change (overall sinkage) and trim (difference between forward and aft drafts)

💭 Think About

• First, find the total added weight and use the appropriate displacement/TPI data from Section 1 to estimate the overall change in mean draft. How much should both drafts increase just from extra weight, before considering trim? • Compute each item’s trimming moment by multiplying the weight by its distance from amidships. Use forward moments as one sign and aft moments as the opposite sign, then combine them to get a single net trimming moment. Does the vessel trim by the bow or by the stern? • Use the trimming moment per inch (or centimeter) from the blue pages to convert the net trimming moment into inches of trim. Then, distribute this trim between the forward and aft drafts based on the vessel’s length between perpendiculars (LBP). How much does the forward draft change compared with the aft draft?

✅ Before You Answer

• Make sure you are using the correct displacement/TPI and MCT (moment to change trim) that correspond to the vessel’s starting condition in the blue pages—not a lightship or maximum displacement value unless that matches the question. • Carefully check your sign convention: decide which direction is positive (e.g., moments causing trim by the bow) and stick with it for all three weights. • After you get the new drafts, confirm that the mean of the final drafts matches the initial mean draft plus the expected mean draft increase from the total loaded weight. If it doesn’t, re-check your math.