Deck General · Metacentric Height (GM)
A vessel's rolling period is measured at 18 seconds. Compared to the same vessel with a period of 10 seconds, the 18-second ship has:
- AA larger GM and is more stable
- BA smaller GM and is more tender✓ Correct
- CThe same GM but a wider beam
- DA negative GM
Explanation
Longer rolling period means smaller GM. A small GM means less righting moment — the vessel is tender. The 18-second roll is a warning sign of reduced initial stability; investigation and corrective action may be required.
Authority: Stability & Trim (USCG deck topic)
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