Powerboats Under 40’, (under power)
On the port side, at the bow, a red sidelight must be displayed, while on the starboard side, at the bow, a green sidelight must be displayed. Both the red and green sidelights must be visible from straight in front of the boat and in a 112.5° arc to stern.
The red and green sidelights are often combined into a bicolor light mounted on top of the bow.
In addition, a 360° all-round white light must also be displayed either at the stern (on smaller powerboats) or on a mast above the bridge (on larger powerboats)
Powerboats Under 40’ (at anchor)
A powerboat at anchor may turn off the red and green navigational lights, and leave just the 360° all-round white light on.
Sailboats (under power)
Must also have the red and green sidelights (or a bicolor light), a white stern light that shines aft and 67.5° on either side of the boat.
Sailboats (at anchor)
When a sailboat anchors at night, it must display a 360° all-round white light.
These are simply the high points of navigation lights; please consult with the US Coast Guard for up-to-the-minute rules and regulations.