A vessel has a maximum allowable draft of 28 feet in salt water and a fresh water allowance of 8 inches. At the loading berth, the water density is 1.011. To what draft can she load in order to be at her marks when she reaches the sea? (The salt water density is 1.025.)
• Fresh water allowance (FWA) and how it relates to changes in water density • The relationship between draft, displacement, and water density (Archimedes' principle) • How to proportionally adjust FWA when the water density is neither full fresh nor full salt
• How does the vessel’s draft change when moving from water of density 1.011 to salt water of density 1.025? Should the draft increase or decrease? • What fraction of the full fresh-to-salt density difference (1.000 to 1.025) is represented by the actual density difference (1.011 to 1.025)? • Once you know that fraction, how can you apply it to the 8-inch fresh water allowance to find the allowable extra immersion at the berth?
• Be sure you are using the correct density difference: compare 1.011 to 1.025, and also 1.000 to 1.025 • Convert all drafts and FWA to the same units (inches or feet) before doing proportional calculations • After calculating the loading draft at the berth, confirm that when the vessel reaches 1.025 density she will be exactly at 28 feet.
No comments yet
Be the first to share your thoughts!