Which signal indicates a vessel is being towed by another vessel?

• A. 1 prolonged followed by 3 short
• B. 1 prolonged followed by two short
• C. 1 long blast every two minutes
• D. 2 short blasts

Answer: (A)

When a vessel is being towed, nearby ships need a clear, recognizable signal to understand the situation and give space for maneuvering. The standardized pattern for being towed is one prolonged blast followed by three short blasts. This exact sequence uniquely communicates that the towed vessel cannot maneuver under its own power and is under tow, so other vessels should proceed with caution and keep clear.

The other signals don’t convey towage status, so they wouldn’t inform other mariners of the tow. For example, different blast patterns relate to other crossing, passing, or maneuvering communications, so they aren’t the recognized indication of towage.