08/04/2026
Understanding Ship Navigation Lights – A Mariner’s Language at Night
At sea, ships don’t rely on signals or horns alone—navigation lights tell the full story of a vessel’s position and movement, especially in darkness or poor visibility.
🔴 Red Light (Port Side)
Positioned on the left side of the ship, the red light covers an arc of 112.5° from dead ahead to the port beam. If you see this light, it means you are viewing the vessel from its port side.
🟢 Green Light (Starboard Side)
Located on the right side, the green light also covers 112.5° from the bow to the starboard beam. Seeing green indicates the vessel’s starboard side is facing you.
⚪ White Light (Stern/Masthead)
White lights are used to indicate direction of travel—either from behind (stern light) or forward (masthead light).
How to Read the Situation:
Red + Green visible → Vessel is coming directly towards you
Only Red → Crossing from your right to left
Only Green → Crossing from your left to right
Only White → Vessel moving away from you
These light sectors are defined under International Maritime Organization rules and part of COLREGS, ensuring safe navigation.
In simple terms, these lights act like “traffic signals of the sea,” helping mariners avoid collisions and navigate safely through the night.
