A port light is a red navigation light located on the left (port) side of a vessel . This light is a mandatory navigation light that helps identify the direction of other vessels, especially when sailing at night or in poor visibility.
1. Characteristics of a port light
✅ Red light → Indicates the left side (port) of a vessel .
✅ Shines in an arc of 112.5° → Only visible to vessels approaching from the front or from an angle to the side .
✅ Mandatory for night navigation or poor visibility → Must be used in accordance with international maritime regulations (COLREGS) .
✅ Combined with a starboard light (green) and stern light (white) → Together they form the standard navigation lights for ships.
✅ Visible over at least 2 nautical miles → Depending on the size of the vessel.
2. Function of a port light
📌 Helps to recognize the direction of travel of a vessel → When you see a red light , you know that you are approaching the left side of a vessel.
📌 Prevents collisions → In combination with other navigation lights, it determines the right-of-way rules on the water .
📌 Part of the basic lighting of a ship → Together with the starboard light (green) and the stern light (white) it indicates orientation and direction of travel .
3. When is a port light required?
According to the International Regulations for Preventing Collisions at Sea (COLREGS), the following vessels are required to display a port light:
| Ship length | Obligation |
|---|---|
| < 7 meters (23 ft) | May be replaced by an all-round white light . |
| 7 - 20 meters (23 - 65 ft) | Port light + Starboard light + Stern light mandatory . |
| > 20 meters (65+ ft) | Port light + Starboard light + Stern light + Mast light mandatory . |
| Sailboats under sail | Port and starboard lights are mandatory (or a three-colour masthead light). |
⛵ Sailing vessels may carry a three-coloured light on the mast instead of separate sidelights.
4. Difference between a port light and other navigation lights
| Light type | Goal | Colour | Corner |
|---|---|---|---|
| Port Light | Indicates the left side of the ship | Red | 112.5° |
| Starboard Light | Indicates the right side of the ship | Green | 112.5° |
| Stern Light | Shows the rear of the ship | White | 135° |
| Masthead Light | Shows the direction of travel (motorboats) | White | 225° |
| Anchor light | Shows an anchored ship | White | 360° around |
💡 Tip: When you see a red port light, you know you're approaching the left side of another vessel. If you see a green starboard light, you're looking at the right side of the vessel.
5. Types of port lights
🔹 LED port lights → Energy efficient, long life.
🔹 12V / 24V boat lights → For motorboats and yachts.
🔹 Portable Navigation Lights → For small boats and kayaks.
🔹 Combination lights → Integrated with starboard light for small vessels.
💡 In short:
The port light is a red navigation light that marks the left side of a vessel . It shines in an arc of 112.5° and is mandatory for vessels sailing at night or in poor visibility. Along with the starboard light (green) and the stern light (white), it ensures safety and visibility on the water .