A bell is used to sound a fog signal for a _____________.

A bell is used to sound a fog signal specifically for a sailing vessel at anchor. This convention is grounded in maritime navigation rules, which dictate that vessels must signal their presence in foggy conditions to prevent collisions.

For a sailing vessel at anchor, utilizing a bell as a fog signal serves as a means of communication to other vessels, alerting them to the anchored vessel's location. The sound of a bell can carry over distances in foggy weather, making it an effective auditory signal. Additionally, this practice is part of the International Regulations for Preventing Collisions at Sea (COLREGS), which outlines specific sound signaling requirements for different types of vessels under varying conditions.

Other types of vessels, such as power-driven vessels underway or vessels not under command, have different signaling methods prescribed by these regulations. Each category of vessel has unique requirements tailored to their operational status and maneuverability during poor visibility. In summary, the bell is an established signal for anchored sailing vessels in fog, highlighting their presence and thus enhancing safety on the water.