A vessel is limited to a maximum draft of 26'-03". The present drafts are: FWD 21'- 04", AFT 24'-06". How much more cargo can be loaded and where should it be located if a drag of 1 foot is desired? (Use the reference material in Section 1, the blue pages, of the Stability Data Reference Book)
• Maximum allowable draft and desired drag (difference between forward and aft drafts) • Using the Stability Data Reference Book to find TPI (tons per inch immersion) and LCF or tipping center data • Relationship between trimming moment = weight × distance and change of trim = trimming moment ÷ MTC (moment to change trim)
• First, figure out how many more inches you can load at the forward and aft drafts to reach the maximum draft and desired drag. What will the final forward and aft drafts be? • Then, using those final drafts, determine how much the mean draft must increase and how much trim must change to reach the target condition. • From the reference book, identify which data you need to convert: (1) the total extra immersion at the mean draft into tons, and (2) the change of trim into a trimming moment. How does that trimming moment tell you where the weight must act relative to the ship’s tipping center or amidships?
• Compute the final forward and aft drafts that give a 1-foot drag with maximum draft not exceeding 26'-03". • From the Stability Data Reference Book, confirm the correct TPI and MTC values for the appropriate mean draft range. • Check whether the calculated lever arm for the added weight is measured from amidships or from the tipping center (LCF) before matching it with the choices.
No comments yet
Be the first to share your thoughts!