Question 383Navigation General

70% to pass

Illustration D037NG below represents a movable dam. If there is high water and the wickets are down so that there is an unobstructed navigable pass through the dam, what light(s) will be shown at D if the lock walls and piers are not awash?

Diagram for USCG Navigation General: Illustration D037NG below represents a movable dam. If there is high water and...
A Three red lights
B One amber light
C One red light
D Two red lights
AI Explanation

The correct answer is C) One red light. When a movable dam has its wickets down and there is an unobstructed navigable pass through the dam, and the lock walls and piers are not awash, the lights to be shown at the dam are one red light, per the U.S. Aids to Navigation System. The red light indicates that the dam is closed to navigation and the passage is open. The other answer choices are incorrect because they do not match the regulation for the specific scenario described.

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