United States Coast Guard Captains License Practice Exam

When underway in restricted visibility, which fog signal does not conform to the requirements?

1. One prolonged blast

2. Two prolonged blasts

3. One prolonged and two short blasts

4. Ringing of a bell for five seconds

The correct answer is: Ringing of a bell for five seconds

When operating in restricted visibility, the fog signal that does not conform to the requirements is the ringing of a bell for five seconds. In maritime regulations, specifically the International Regulations for Preventing Collisions at Sea (COLREGS), a vessel underway must follow specific sound signal protocols when visibility is low due to fog or other conditions. A prolonged blast is a common sound signal for power-driven vessels, indicating their presence. Similarly, two prolonged blasts signify that a vessel is at anchor, while the combination of one prolonged and two short blasts is used by vessels making way through the water. Each of these sound signals serves a distinct purpose in informing others of the vessel's status and intentions. In the case of the ringing of a bell, while it may be used by vessels at anchor or for signaling purposes, it does not meet the specific requirements laid out for vessels underway in restricted visibility. Instead, the emphasis in these situations is on sound signals that clearly communicate the movement or status of a vessel to prevent collisions. Thus, the ringing of a bell for a fixed duration does not align with the needed communication standards for vessels operating in restricted visibility.