Question 640 Rules of the Road

90% to pass

BOTH INTERNATIONAL & INLAND You see a vessel displaying three lights in a vertical line. The highest and lowest lights are red and the middle light is white. She is also showing a white light at the stern, which is lower than the forward light. Which vessel could you be observing?

A a vessel not under command
B a pilot vessel with port side to you
C a vessel aground
D a survey vessel
AI Explanation

The correct answer is D) a survey vessel. The display of three vertical lights, with the highest and lowest being red and the middle being white, along with a white light at the stern lower than the forward light, is the navigation light configuration for a survey vessel according to the International and Inland Navigation Rules. The other options are incorrect because: A) A vessel not under command would display two red lights in a vertical line. B) A pilot vessel with port side to you would display a single white light at the masthead. C) A vessel aground would display an all-round white light instead of the specific light configuration described.

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