45. A bulk freighter 680 ft. in length, 60 ft. beam, with a waterplane coefficient of .84, is floating in salt water at a draft of 21'. How many long tons would it take to increase the mean draft by 1″?

The waterplane area is calculated, and the volume displaced by a 1-inch draft increase is determined. This volume is then divided by the salt water displacement of 35 ft3/long ton to find the required weight, resulting in 81.6 long tons.