Your vessel has a displacement of 19,800 tons. It is 464 feet long, and has a beam of 64 feet. You have timed its rolling period to be 21.0 seconds in still water. What is your vessel's approximate GM?

Correct Answer: Option D — 1.8 ft

Transposing the rolling period formula to solve for metacentric height yields GM = (0.35 * B / T)^2. Using a 64-foot beam and a 21.0-second roll period calculates to an approximate GM of 1.8 feet.