Crossing

Rule 15

When two power-driven vessels are crossing with risk of collision:

the vessel that has the other on its starboard side must keep out of the way

where circumstances admit, the give-way vessel should avoid crossing ahead

Inland nuance

Special provisions apply on certain rivers where vessels are crossing a river.

Do not teach "boat on the right always wins." Rules 9, 10, 13 and special circumstances can change the analysis.