Displacement is the weight of the boat measured in long tons. True or false?

• A. True
• B. False
• C. Only if wooden hull
• D. Only if full load

Answer: (A)

Displacement is the weight of the water the hull must displace to float, which equals the weight of the vessel itself. This follows Archimedes’ principle: at float, the weight of the ship is exactly balanced by the weight of the water it displaces. In naval practice, this weight is expressed in tons, and traditionally long tons (1 long ton = 2240 pounds) are used for displacement. So the statement that displacement is the weight of the boat measured in long tons is correct in the common convention. (Keep in mind that in other regions or contexts you might also see metric tons or short tons used, but the fundamental idea remains the same.)