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"?

Correct Answer: Option B — 81.6 tons

Tons per inch immersion in salt water is calculated using the formula: TPI = (Length * Beam * Waterplane Coefficient) / 42. Substituting the given values: (680 * 60 * 0.84) / 42 = 81.6 long tons per inch.