Your vessel is limited to a maximum draft of 26'-03". The present drafts are: FWD 22'-10", AFT 23'-08". How much more cargo can be loaded and where should it be located if a drag of 18 inches is desired? (Use the reference material in Section 1, the blue pages, of the Stability Data Reference Book)
• Maximum allowable draft versus present mean draft and desired drag (difference between aft and forward drafts) • Using the Stability Data Reference Book (blue pages, Section 1) to find tons per inch immersion (TPI) and the trimming moment per inch (MTI/MT1) at the relevant draft • Relationship between trimming moment = weight × distance from tipping center and resulting change in forward and aft drafts
• First, determine how many inches of draft you can still take on before reaching the maximum draft at the deeper end once the desired drag of 18 inches is achieved. How does this limit the final mean draft? • Figure out whether you need the aft or forward draft to reach the maximum allowable value when you have 18 inches of drag, then compute the final forward and aft drafts and the new mean draft. • Using the blue pages, find the TPI at the new mean draft to get the total tons you can add overall, then use the trimming tables (or MTI/MT1) to see what trimming moment is required to create 18 inches of drag from the original condition. From that, work out how far the added weight must be from the tipping center.
• Carefully confirm the initial drag from the given forward and aft drafts before doing any trim calculations. • Verify you are using the correct TPI and MTI/MT1 values from the Stability Data Reference Book corresponding to the proper drafts. • Before choosing an answer, check that both the amount of cargo (tons) and the location (distance and direction from amidships or tipping center) are consistent with the trimming moment you calculated.
No comments yet
Be the first to share your thoughts!