When boating at night what does a red on a vessel tell you?

Answer 1

The head and port side of the vessel is toward you

Answer The red light is the port side light which is on the left side of the boat. So if you can only see the red light, the boat has its left side toward you with its bow to the left of the red light and the stern to the right of the red light.

If you can only see the red light, then that boat has the right of way and you have to manoeuvre to avoid it. The default manoeuvre is to steer starboard (right)which will take you behind the other boats direction of travel.

(The starboard (right) side light is green.)