A stern light is a white navigation light located at the stern of a vessel . It is a mandatory navigation light that helps vessels be seen at night and prevents collisions at sea or inland waterways.
1. Features of a stern light
✅ White lighting → Does not burn all around , but at an angle of 135° behind the ship.
✅ Mandatory for all sailing vessels → Must burn during night navigation or in poor visibility .
✅ Placed at the rear (fence) of the ship → Visible to oncoming traffic.
✅ Visibility at least 2 nautical miles → In accordance with the International Regulations for Preventing Collisions at Sea (COLREGS) .
✅ Works with other navigation lights → Used in conjunction with side lights (port/starboard) and masthead lights .
2. Function of a stern light
📌 Warns approaching vessels → Shows that there is a vessel sailing ahead of them .
📌 Part of the navigation lighting system → Helps vessels identify each other based on the color and placement of lights .
📌 Helps with course determination → Approaching vessels only see a white stern light , which lets them know that the vessel is moving ahead .
3. When is a stern light mandatory?
According to the COLREGS (International Regulations for Preventing Collisions at Sea) :
| Ship length | Fence light obligation |
|---|---|
| < 7 meters (23 ft) | Mandatory if possible, but may be combined with an all-round white light . |
| 7 - 20 meters (23 - 65 ft) | One stern light required. |
| > 20 meters (65+ ft) | One stern light + other navigation lights mandatory. |
| Sailboats under sail | One stern light , unless a tricolour masthead light is used. |
⛵ Sailing vessels under sail may carry a tricolour light on the mast instead of separate side and stern lights .
4. Difference between a stern light and other navigation lights
| Light type | Goal | Colour | Corner |
|---|---|---|---|
| Stern Light | Shows the rear of the ship | White | 135° |
| Port light | Indicates left side | Red | 112.5° |
| Starboard light | Indicates right side | Green | 112.5° |
| Masthead Light | Shows the direction of travel (motorboats) | White | 225° |
| Anchor light | Shows an anchored ship | White | 360° around |
💡 Tip: A motorboat always carries a masthead light + stern light, while a sailboat only needs to carry a stern light and side lights.
5. Types of stern lights
🔹 LED Fence Lights → Energy efficient, long lifespan.
🔹 12V / 24V Stern Lights → For motorboats and yachts.
🔹 Portable Stern Lights → For small boats and rowboats.
🔹 Combination lights → Integrated with side lights for small vessels.
💡 In short:
The stern light is a white navigation light located at the stern of a vessel , covering an angle of 135° . It warns approaching vessels and is mandatory on all vessels underway during nighttime navigation and poor visibility .