Under the Rules, what is the requirement for a vessel that sees another vessel approaching in a narrow channel?

The requirement for a vessel that sees another vessel approaching in a narrow channel is to reduce speed and be prepared to take evasive action. This is essential for ensuring safety in narrow channels where the maneuvering space is limited. When two vessels are navigating a narrow channel, there is an increased risk of collision due to restricted space, and maintaining awareness of other vessels and potential hazards is crucial.

By reducing speed, the vessel has more time to assess the situation and make informed decisions. Additionally, the ability to take evasive action is critical in preventing accidents and ensuring that both vessels can safely navigate. This response aligns with the principles laid out in the Navigation Rules, specifically those dealing with vessel conduct in restricted visibility and confined waterways.

The other options do not align with the best practices for navigation in narrow channels. Maintaining course and speed at all times would increase the risk of collision and does not take into account the need for adjusting to other vessels’ maneuvers. Ignoring the other vessel would violate the duties of vigilance and safe navigation required under the Rules. Sounding the horn frequently is not a requirement for communication in this context; rather, it should be used as a signal when necessary, but it does not replace the need for prudent navigation.