Which vessel would NOT sound a fog signal of one prolonged blast and two short blasts?

• A. A vessel being towed
• B. A power-driven vessel underway in fog
• C. A sailing vessel under sail
• D. A vessel at anchor in fog

Answer: (A)

In restricted visibility, ships use standardized fog signals to convey their status. The pattern of one prolonged blast followed by two short blasts is the signal that a power-driven vessel is underway or making way through the water.

A vessel being towed is not under its own power, so it does not use that same signal to indicate its status. The towed vessel’s movement is controlled by the towing vessel, and its signaling differs to reflect that it is being pulled rather than propelled. Therefore, that one-long, two-short pattern would not be appropriate for a vessel being towed.

The other scenarios involve vessels that would typically emit the standard underway signal or other signals appropriate to their status (a power-driven vessel underway would use the same pattern; a sailing vessel or a vessel at anchor has their own distinct signals in fog).