Safety & Environmental Protection (Deck) USCG Question #2416 (Set 74)

Your vessel displaces 869 tons and measures 136'L x33'B. You ship a large wave on the after deck which measures 52'Lx 33'B. The weight of the water is estimated at 52.8 tons. What is the reduction in GM due to free surface before the water drains overboard?

Official USCG Answer & Rule Citation

Correct Answer: Option A — 4.83 feet

Uncontained water on an after deck reduces effective GM based on the moment of inertia of the free surface area. Applying FSC = (l * b^3) / (12 * V) for 52.8 tons of water on a 52' by 33' deck gives 4.83 feet.

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