BOTH INTERNATIONAL & INLAND In illustration D005RR below, vessel "A", which is pushing ahead, and vessel "B" are crossing. Which is the stand-on vessel?

Correct Answer: Option B — Vessel "B" is the stand-on vessel because she is to starboard of vessel "A".

Rule 15 mandates that the vessel having the other on her starboard side is the give-way vessel. Since Vessel B is to the starboard of Vessel A, Vessel B is the stand-on vessel and Vessel A must take early and substantial action to keep well clear.