A masthead light is a white navigation light located at the front and top of a vessel . This light is mandatory for motorboats and vessels longer than 7 meters and helps indicate the vessel's direction of travel .
1. Features of a top light
✅ White lighting → Indicates that a vessel is operating under motor .
✅ Shines in an arc of 225° → Visible from straight ahead to 22.5° abaft to port and starboard .
✅ Mandatory on motorboats and large ships → Must be lit when sailing at night or in poor visibility .
✅ Mounted high on the mast or a support → Provides maximum visibility.
✅ Visibility minimum 2 to 6 nautical miles → Depending on the size of the vessel.
2. Function of a top light
📌 Inform other vessels that the vessel is motor-driven .
📌 Helps determine the direction of travel → Together with the side lights (port and starboard) it makes it clear which way the ship is sailing.
📌 Prevents collisions → Essential for applying the right-of-way rules on the water .
💡 Important: A sailing vessel operating under sail only is not required to display masthead lights, but a motorboat always is .
3. When is a top light mandatory?
According to the International Regulations for Preventing Collisions at Sea (COLREGS), the following vessels are required to display a masthead light:
| Ship length | Top light obligation |
|---|---|
| < 7 meters (23 ft) | No top light required unless visibility is poor (may be replaced by all-round white light). |
| 7 - 12 meters (23 - 39 ft) | One masthead light + sidelights + stern light. |
| > 12 meters (39+ ft) | One masthead light + sidelights + stern light. |
| > 50 meters (164+ ft) | Two masthead lights at different heights + sidelights + stern light. |
| Sailboats under sail | No masthead light required (but port and starboard lights are required). |
⛵ Sailing boats are not required to carry a masthead light . They may instead use a tricolor light at the masthead .
4. Difference between a masthead light and other navigation lights
| Light type | Goal | Colour | Corner |
|---|---|---|---|
| Masthead Light | Indicates the direction of travel (motorboats) | White | 225° |
| 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° |
| Anchor light | Shows an anchored ship | White | 360° around |
💡 Tip: A motorboat always carries a masthead light, a sailboat only when it is also using the engine.
5. Types of top lights
🔹 LED top lights → Energy efficient, long lifespan.
🔹 12V / 24V navigation lights → For motorboats and yachts.
🔹 Combination lights → Top light integrated with side lights.
🔹 Two masthead lights (for large vessels) → Second light is placed higher for extra visibility.
💡 In short:
The masthead light is a white navigation light required for motorboats and shines in a 225° arc . It helps determine sailing direction , is mounted high on the boat, and works in conjunction with the sidelights and sternlights for maximum visibility on the water.