The short answer
A navigation light is not chosen based solely on electrical power or the shape of the housing. First, identify the configuration required by the type of boat, its length, and its situation. Then verify for each light the color, angular sector, nominal range, and declared certification. Installation must respect the manufacturer’s orientation, preserve the sectors without masking caused by rigging or deck equipment, and maintain a reliable power supply. An LED that consumes little power does not justify arbitrarily reducing cable cross-section, protection, or connection quality. Before night sailing, test each function from outside the boat and keep an appropriate backup procedure.
Start from the boat’s regulatory configuration
The COLREG rules dedicate Part C to lights and shapes. They define colors and sectors, minimum ranges, and expected combinations based on the vessel and its situation. The requirements for a sailboat under way are therefore not the same as for a powerboat, a moored vessel, or a large ship.
Before purchasing, write down four pieces of information:
- Overall length of the boat;
- Propulsion and intended use when the light will be in operation;
- Desired function: side, stern, masthead, tricolour, anchor, or combination;
- Actual available space and visibility around that location.
This method prevents confusing a 360° white anchor light, a 225° white masthead light, and a 135° white stern light. They are not interchangeable simply because their color is the same.
Check sectors before comparing range
The angles listed on product sheets describe the zone in which the light must be visible. Common values are 112.5° for a side light, 225° for a masthead light, 135° for a stern light, and 360° for an all-round light. A tricolour light combines several sectors in a single unit but must be precisely aligned with the boat’s axis.
Range in nautical miles is another criterion. It must be verified for the exact model, as the same family can exist in 1, 2, 3, or 5 MN versions. Do not transpose the range from one version to another. For example, the Mantagua catalogue includes side lights, masthead lights, anchor lights, and combined units with different sectors and ranges.
Choose between separate lights and a combined light
Separate lights allow each function to be positioned where its sector is least obstructed. They also simplify replacement of a single unit. On the downside, they multiply cables, protections, connections, and inspection points.
A combined or tricolour light at the masthead reduces the number of devices and can improve visibility above deck. It does, however, require careful alignment, power routed up the mast, and a clear strategy in case of failure. Also confirm that the combination exactly matches the intended mode of navigation: the presence of an anchor or strobe function on the product does not mean it must be used simultaneously with the underway sectors.
Prepare an installation without masked zones
A compliant light can become ineffective if installed behind a pulpit, sail, radar, solar panel, or dinghy. Test-fit the light at its location before drilling and observe the boat from multiple angles. For a sector light, respect the fore/aft, port/starboard markings and the trim specified in the manual.
The mounting surface must remain rigid. A housing that tilts or rotates with vibration shifts the sector boundaries. Cable runs must be protected against abrasion and water ingress without placing strain on the light. The manufacturer’s instructions remain the primary reference for position, torque, drilling, and sealing.
Power and protect the circuit
Size the cable for current, round-trip length, and allowable voltage drop. Install protection matched to the conductor and equipment, then label the circuit at the panel. Distribution components from Blue Sea Systems or BEP can organize protection and switching, but their rating must be calculated for the actual installation.
Avoid unprotected splices at the foot of the mast or in a damp area. A corroded connection can allow an LED to light at the dock while causing voltage drop or intermittent failure at sea. After installation, measure voltage at the light in operation and check for overheating at connections.
Organize a pre-departure check
A proper check is not simply looking at panel indicators. Turn on each function separately, walk around the boat, and verify color, apparent intensity, sector, absence of glare, and absence of incompatible simultaneous functions. On a sailboat, check the masthead light from deck level and, if possible, from a distance.
Record the light’s reference, voltage, protection, cable routing, and date of the last check. Keep on board the replacement or backup signalling means specified for your voyage.
Selection checklist
- COLREG configuration identified for the boat and situation.
- Color, sector, and range read from the exact model.
- Certification and manual available.
- Unobstructed space across the entire useful sector.
- Orientation and mechanical support verified.
- Cable, protection, and switching sized correctly.
- Outdoor test performed for each mode.
Frequently asked questions
Does a 2 MN LED light suit every boat?
No. Required range depends on vessel type, length, and the light’s function. Check applicable rules and certification for the exact model.
Can an incandescent bulb be replaced with an LED?
Only if the light manufacturer authorizes that source and the assembly retains its photometric and regulatory characteristics. A bulb that fits the socket does not guarantee sector, color, or range.
Why is the orientation of a side light important?
Because its visibility limit is part of the information transmitted to other vessels. Rotation or tilt can shift the red or green sector and create ambiguity.
Is a separate circuit required for navigation lights?
It is prudent to have clearly identified switching and protection to prevent accessories from cutting or disrupting the lights. The final wiring must comply with applicable standards and the boat’s specifications.
