🔍 Key Concepts

• Use the rolling period – GM formula that relates the natural rolling period (T), beam (B), and metacentric height (GM) for ships in feet and seconds. • Remember that when you solve for GM, you’ll need to square one of the terms, so watch your algebra carefully. • Be sure to plug beam in feet and period in seconds into the correct places in the formula.

💭 Think About

• Which standard stability formula links T, B, and GM for a vessel in salt water? Once you recall it, rearrange it to solve explicitly for GM. • After rearranging, are you correctly applying the square to the right part of the expression (numerator or denominator)? • Once you calculate a numerical value for GM, which of the choices is closest to your computed result?

✅ Before You Answer

• Confirm that you are using beam (21 ft), not length (128 ft), in the rolling period formula. • Confirm that you are using the period T = 6 seconds, not the draft, in the formula. • After computing, double-check that your final GM is in feet and that you didn’t forget to square or take a square root where required.