On a vessel of 5,000 tons displacement there are two slack tanks of acid (SG 1.8). Each tank is 30 feet long and 20 feet wide. What is the reduction in metacentric height due to free surface with the vessel in sea water (SG 1.025)?
• Free surface effect and how it reduces metacentric height (GM) • Correct formula for free surface moment (FSM) in feet-tons for a slack tank • Effect of specific gravity (SG) of both the liquid in the tank and the surrounding seawater on the GM correction
• How do you compute the free surface moment for a rectangular tank, and how does the breadth of the tank factor into that formula? • Once you have the total free surface moment for both tanks, what do you divide it by to convert that moment into a reduction of GM for the whole vessel? • How does the difference between the liquid’s SG (1.8) and seawater SG (1.025) change the value of the GM correction compared with the case where the liquid and seawater have the same SG?
• Confirm you are using the correct free surface moment formula for a rectangular slack tank and not confusing it with a second-moment-of-area formula unrelated to stability. • Be sure you convert the vessel’s displacement (5,000 tons) and any moments into compatible units before dividing to get GM in feet. • Double-check how to apply the SG ratio (liquid vs. seawater) to adjust the free surface correction before comparing to the multiple-choice answers.
No comments yet
Be the first to share your thoughts!