Navigation Lights – Sidelights

Chris Riley by Chris Riley Updated on July 30, 2019. In nauticalknowhow

During factory and boat show inspections we have observed that many manufacturers of recreational boats do not have a good understanding of the navigation rules governing proper installation of navigation lights. The requirements are found in the Navigation Rules, International-Inland, and in Parts 81, 84 and 89 of Title 33, Code of Federal Regulations. The problem appears to be particularly prevalent for manufacturers located in the western States. Since most manufacturers routinely equip the boats they produce with navigation lights, navigation light installations are routinely inspected and discussed during factory visits and boat shows.

One problem that has increased recently is the installation of flush mounted sidelights in the boat hulls, usually below the rub rail. Many manufacturers build boats using similar sidelight fixture installations. This is a dangerous trend which is likely to end up costing somebody a pile of money when a plaintiff’s attorneys go after everyone who might have been for liable for a serious collision.

boatlites.gif (3948 bytes) Sidelights that meet the rules are designed to cover an arc of the horizon, or sector, of 112.5 degrees. Intensities are required to attain a visible range of 1 mile for vessels less than 12 meters (39.4 ft.) and 2 miles for vessels 12 meters or longer. These fixtures are designed for intensities to decrease and reach practical cutoff between 1 and 3 degrees outside their prescribed sector. Sidelight fixtures must be installed parallel with the fore and aft centerline of the vessel and arranged to show an unbroken light from right ahead to 22.5 degrees abaft the beam, a total sector arc of 112.5 degrees.

Sidelights that are installed in the contour of the bow without providing a mounting surface tooled to be parallel with the fore and aft centerline of the vessel are not in compliance with the Inland or International Navigation Rules. Depending on the breadth of the vessel near the bow and how far aft from the vessel’s stem the lights are mounted, this shift can be more than 20 degrees in some cases. Installing the fixtures too far aft of the vessel’s stem may result in the sidelights not being visible from a position dead ahead.

Another factor in proper installation of sidelights is that they must maintain their required minimum intensity in a vertical sector from 5 degrees above to 5 degrees below the horizontal. They must also maintain at least 60 percent of their minimum required intensity from 7.5 degrees above to 7.5 degrees below the horizontal. Installing flush mounted sidelights, designed to be mounted to a vertical surface in the hull contour, without providing a mounting surface tooled to be vertical, shifts the vertical coverage sector. This also results in a noncompliance with the Inland or International Navigation Rules.

Additionally, most of these flush mounted sidelights are installed below the vessel’s rub rail. International Navigation Rules require that sidelights be installed above the uppermost continuous deck. Therefore this configuration would not be in compliance with International Navigation Rules.

When separate red and green sidelight fixtures are used, the masthead or all-round white light, whichever configuration is installed, must be located as close as practical to the vessel’s fore and aft centerline. For vessels less than 12 meters in length, the masthead or all-round light may be displaced from the fore and aft centerline providing that the sidelights are contained within a common fixture and mounted on the vessel’s fore and aft centerline. The masthead or all-round light must be installed at least one meter (3.3 ft.) above the sidelights.




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