1. (a)When two power-driven vessels are meeting on reciprocal or nearly reciprocal courses so as to involve risk of collision, each shall alter her course to starboard so that each passes on the port side of the other.
2. (b)Such a situation exists when a vessel sees the other ahead or nearly ahead — by night she would see both masthead lights in a line and/or both sidelights, and by day the corresponding aspect.
3. (c)When in any doubt whether such a situation exists, a vessel shall assume that it does and act accordingly.