Which fog signal is used when a vessel being tow ed is in fog?

• A. One prolonged followed by three short blasts
• B. One prolonged blast
• C. Three short blasts
• D. Two prolonged blasts

Answer: (A)

In restricted visibility, signals are used to quickly convey a vessel’s status so others can keep clear. When a vessel is towing another vessel, the required fog signal is one prolonged blast followed by three short blasts, repeated as needed. This pattern specifically communicates that there is a tow and that maneuverability is limited, so nearby vessels should give extra room and proceed cautiously. The signal is typically emitted by the towing vessel, not the towed one, because the tow cannot steer or control its own movement. Other fog signals are used for different situations (altering course, stopping, etc.), but they don’t indicate a towing arrangement, so they wouldn’t be appropriate here.