Under the International Rules, which vessel is not permitted to display yellow lights?

Under the International Rules, which vessel is not permitted to display yellow lights?

• A. U.S. submarines
• B. All submarines
• C. Sailing vessels
• D. Vessels not under command

Answer: (A)

Yellow lights are reserved for specific, limited uses as an extra signal beyond the standard red, green, and white navigation lights. They are not part of the ordinary signaling for most vessels, and using them can mislead other mariners about a vessel’s status or maneuvering intentions. Submarines—including U.S. submarines—are not authorized to display this amber signal under the International Rules. They must use the regular navigation lights when on the surface, so a yellow light would create confusion rather than convey a clear status.

Yellow lights are reserved for specific, limited uses as an extra signal beyond the standard red, green, and white navigation lights. They are not part of the ordinary signaling for most vessels, and using them can mislead other mariners about a vessel’s status or maneuvering intentions. Submarines—including U.S. submarines—are not authorized to display this amber signal under the International Rules. They must use the regular navigation lights when on the surface, so a yellow light would create confusion rather than convey a clear status.