BOATsmart! Base de connaissances du Canada 

If you meet a vessel and see a green, red and white light, you are approaching another power-driven vessel head-on. In this situation neither vessel has the right-of-way. Both operators must take early and substantial action to steer well clear of the other vessel. Both operators should reduce their speed and steer to starboard.

If you meet a vessel and see a green and red light but no masthead (white) light, then you are approaching a sail-driven vessel. You are the give-way craft and must yield right-of-way to the sailing vessel.