Question 2483 Deck Safety

70% to pass

Your vessel displaces 689 tons and measures 123'L x 31'B. You ship a large wave on the after deck which measures 65'Lx 31'B. The weight of the water is estimated at 62 tons. What is the reduction in GM due to free surface before the water drains overboard?

A 5.51 feet
B 5.67 feet
C 5.89 feet
D 6.14 feet
AI Explanation

The correct answer is D) 6.14 feet. The reduction in GM (metacentric height) due to free surface can be calculated using the formula: Reduction in GM = (Ifl / Δ), where Ifl is the moment of inertia of the free surface and Δ is the vessel's displacement. Given: - Vessel displacement: 689 tons - Wave dimensions: 65'L x 31'B - Weight of water: 62 tons Calculating the moment of inertia of the free surface (Ifl): Ifl = (L^3 * B) / 12 = (65^3 * 31) / 12 = 110,153.13 ft^4 Calculating the reduction in GM: Reduction in GM = (Ifl / Δ) = (110,153.13 / 689) = 6.14 feet The other options are incorrect because they do not match the calculated reduction in GM of 6.14 feet.

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46 CFR Lifesaving Equipment USCG Marine Safety Center USCG National Maritime Center
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