Question 694 Rules of the Road

90% to pass

BOTH INTERNATIONAL & INLAND A white masthead light shows through an arc of how many degrees?

A 90°
B 112.5°
C 225°
D 360°
AI Explanation

The correct answer is C) 225°. According to the requirements for masthead lights on vessels, a white masthead light must show an unbroken light over an arc of the horizon of not less than 225 degrees, and so that it is visible from dead ahead to 22.5 degrees abaft the beam on either side of the vessel. This applies to both international and inland navigation rules. The other options are incorrect because: A) 90° is too narrow of an arc, B) 112.5° is also too narrow, and D) 360° would be a full, unbroken circle, which is not the requirement.

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Official Resources
USCG Navigation Rules (COLREGS) 33 CFR Navigation Rules USCG Navigation Center
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