Navigation lights, green starboard and red port. Masthead and stern lights should be white
a sailing vessel is approaching head on and you must give way
fishing at night
A green light is on the starboard side of the vessel. So it may mean that the starboard side is directly facing you.
Sailing vessel is approaching head on you must give away
Sailing vessel is approaching head on you must give away
Sailing vessel is approaching head on you must give away
It would mean that the other vessel is bow on to where you are looking.
The same thing it does during the day.
a sail boat is heading straight at you
Each light on a vessel has a certain viewing angle. The red and green lights have a 22.5 degree arc abaft the beam to the bows viewing angle and indicate whether you are in front of, left (Port) or right (Starboard) side to the vessel. If you saw just the red and green lights at the same time you would have been directly in front of the vessel since these lights are not visible from the stern. you should have noticed the main mast light also which is visible from 22.5 degrees abaft the beam starboard to 22.5 degrees abaft the beam port. If you didn't see the main light and port and starboard lamps you were directly in front of the vessel and somebody needed to change the main light bulb either that or you were in collision and sank before you noticed it.
a sail boat is heading straight at you
A white light used by itself which can be seen in all directions is the anchor light, which means you are anchored. A white used in conjunction with bow lights (green and red) are your navigation lights. The white light indicates your stern ( back of boat). If all you can see is the white light, a boat is either anchored or underway going away from you.