You are on watch in fog. Which vessel is "in sight"?

In the context of navigating in fog, the term "in sight" refers specifically to a vessel that is visible from the bridge of your vessel. This principle is critical for ensuring safe navigation and communication with other vessels in reduced visibility conditions. When a watchstanding officer can see another vessel, they are able to assess its position, course, and speed, which are essential for making informed navigational decisions.

While a vessel that you can hear or that is sounding its horn may indeed be present nearby, auditory signals alone do not confirm its location or ensure safe maneuvering. Similarly, while a vessel displaying lights is providing visual cues, these may not be sufficient for determining if the vessel is "in sight" unless it can be clearly seen from the bridge. Thus, the key factor that defines a vessel as being "in sight" is the ability to visually identify it, which is why the correct answer emphasizes the visual aspect from the bridge.