🔍 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.