When power-driven vessels meet in a narrow channel with a tidal stream, which vessel is the stand-on vessel?

In a narrow channel with a tidal stream, the vessel traveling with the current is considered the stand-on vessel. This is due to the principle that the vessel benefiting from the current has a reduced ability to maneuver because of the influence of the water flow on its navigation. The stand-on vessel must maintain course and speed, allowing the give-way vessel to take appropriate action to avoid a collision.

The rationale behind this is that the vessel moving with the current, while perhaps in a more advantageous position in terms of speed and momentum, needs to comply with the navigational rules that dictate that it should not alter its course unnecessarily. Thus, the vessel going against the current is typically expected to yield to the vessel moving with it to prevent a hazardous situation in the constrained space of a narrow channel. This establishes a clear guideline for safe navigation under these specific circumstances.