Under what condition can a vessel cross a narrow channel or fairway?

Vessels can cross a narrow channel or fairway only if they do not impede the passage of another vessel that must navigate safely within that channel. This principle is crucial for maintaining safe navigation and preventing collisions, as narrow channels typically have limited space and predictable traffic flows. The regulations emphasize the responsibility of mariners to ensure that their actions do not obstruct vessels that are constrained by their draft or other navigational limitations within the channel.

The guidance provided by the COLREGs highlights the importance of prioritizing the safe transit of vessels that may lack the maneuverability to change course or speed effectively. By adhering to this condition, vessels can contribute to the overall safety and efficiency of maritime navigation in confined waters.

While the presence of other vessels (as referenced in one of the other answer choices) may impact a vessel's decision-making, it is not sufficient reasoning to justify crossing the channel unless it is ensured that passage is not hindered for those vessels required to navigate within. Similarly, the size of the vessel or maintaining speed does not take precedence over the obligation to avoid impeding other vessels that have a specific need to use that channel safely.