You are providing onboard training to your engineers on the factors affecting trim and stability. What instructions do you give your engineers to stabilize the ship should it experience an unstable rolling behavior?
• Metacentric height (GM) and its effect on roll period (stiff vs tender ship) • How adding or removing ballast low in the ship on the centerline affects GM and stability • Difference between correcting list (angle of heel at rest) and correcting unstable rolling (too quick or violent roll)
• Think about whether you want to make the ship "stiffer" (quick, violent roll) or "tender" (slow, easy roll) to reduce uncomfortable, unstable motion. • Ask yourself which action will raise the center of gravity (G) and which will lower it, and how that changes GM. • Consider whether using wing tanks on one side or dealing with list actually addresses the problem of unstable rolling when the ship is otherwise upright.
• Before choosing, decide whether unstable, snappy rolling means GM is too large or too small. • Check which option changes weight low on the centerline versus high or off-center, and how that affects GM. • Verify which choice is about correcting list rather than directly improving the ship's overall stability characteristics.
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