Question 149Navigation General

70% to pass

During daylight hours black double-cone topmarks are the most important feature of cardinal marks. Which of the four topmarks shown in illustration D030NG below indicates the best navigable water lies to the west of the buoy?

Diagram for USCG Navigation General: During daylight hours black double-cone topmarks are the most important feature...
A A
B B
C C
D D
AI Explanation

The correct answer is C. The black double-cone topmark indicates a west cardinal mark, which means the best navigable water lies to the west of the buoy. This is according to the International Association of Lighthouse Authorities (IALA) buoyage system used in the United States. The other topmark options do not represent the west cardinal mark, so they would not indicate the best navigable water is to the west.

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