Question 412General Subjects - 1st Asst/Chief

70% to pass

Suppose a water-lubricated stern tube bearing is being evaluated for wear where the propulsion machinery is located amidship. If the tailshaft diameter is 10.5 inches, according to 46 CFR regulations pertaining to periodic tests and inspections as related to machinery and equipment, what would be the maximum clearance diameter permissible before the bearing must be re-bushed?

A0.125 inches
B0.25 inches
C0.3125 inches
D0.375 inches
AI Explanation

The correct answer is C) 0.3125 inches. According to 46 CFR 61.20-15, which covers periodic tests and inspections of machinery and equipment, the maximum clearance permitted for a 10.5-inch diameter tailshaft is 0.3125 inches. This regulation specifies the maximum allowable bearing clearance for various shaft diameters, with the 0.3125-inch limit applying to shafts between 10 and 11 inches in diameter. The other options are incorrect because A) 0.125 inches is too small, B) 0.25 inches is too small, and D) 0.375 inches is too large, as they do not match the regulatory requirement for a 10.5-inch shaft diameter.

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