Which light configuration is used for towing astern on both international and inland waters?

• A. Yellow Over Yellow
• B. White Over White
• C. Red Over Red
• D. Yellow Over White

Answer: (D)

When a vessel is towing another vessel astern, it carries a special two-light signal to alert others. The configuration is a yellow light above a white light. The yellow light identifies the tow, while the white light is the normal stern light, together signaling that towing is in progress. This standard appears in both international and inland rules, so mariners on either waterway recognize it consistently.

Other patterns don’t signal towing astern. Two white lights wouldn’t convey the towing action, two yellows aren’t the required signal, and red patterns aren’t used for this purpose. The yellow-over-white arrangement uniquely communicates “towing astern.”