The USCG issued a Marine Safety Alert on this potential issue after numerous reports surfaced of degraded radio communications.

Interested in learning more about navigational lighting, what different light represent, and how to identify boats by their lighting pattern? Check out our course on Boaters University called Fundamentals of Seamanship: Navigational Rules. Use the promotional code PASSAGEMAKER for 20% off.

Last week, the United States Coast Guard issued a Marine Safety Alert regarding LED navigation lights and VHF and AIS reception. After receiving multiple reports from various mariners including crews, ship owners, and inspectors of poor VHF and AIS reception when antennas were situated near LED lights, the USCG issued this alert.

The USCG is concerned about how this radio interference could affect maritime safety having determined that LED lamps create radio frequency interference and have caused recorded incidences of degraded VHF and AIS communication.

LED lights can cause interference with both AIS and VHF antennas.

LED lights can cause interference with both AIS and VHF antennas.

This is not to say you should stop using LED lighting, as LED lights have been shown to have great power saving benefits aboard vessels. Reception interference can also be difficult to assess. The USCG had recommended the following test to see if you can notice interference with your VHF radio. As interference is created by LED proximity to antennas, the most common culprits are navigation lights and spot lights, however, interior lights and deck flood lights can also cause issues. Mariners should test all onboard LED lighting via the following method.

  1. Turn off LED lights 
  2. Tune VHF radio to a quiet channel (USCG gives Ch 13 as an example, though this may not be the best channel in all waterways)
  3. Adjust the VHF radio's squelch control until the radio outputs audio noise. 
  4. Re-adjust the VHF radio’s squelch control until the audio noise is quiet, only slightly above the noise threshold. 
  5. Turn on the LED light(s), do this for each circuit/type of lights (spotlight, navigation lights, deck lights, interior lights (by area of the boat).
    1. If the radio now outputs audio noise, then the LEDs have raised the noise floor. (Noise floor is generally the amount of interfering signals / static received beyond the specific signal or channel being monitored.)
    2. If the radio does not output audio noise, then LEDs have not raised the noise floor.
USCG Certified LED Navigation Lights from Marinebeam.

USCG Certified LED Navigation Lights from Marinebeam.

Make sure to test all lights in a systematic way so that you can isolate any potential problem areas. You may run into interference from multiple LED circuits (such as navigation lights and a search light or deck lights). You are most likely to have issues with LEDs that are in close proximity to your antenna or antenna wires, however, test all your LED circuits for best piece of mind.

Another thing to note is that not all LED Navigation lights are created equal. As Practical Sailor points out in this article from 2016, it is important to make sure any LED navigation lights you buy are marked with the following: 

  • USCG Approval 33 CFR 183.810
  • Meets ABYC A-16 or equivalent
  • Tested by an approved laboratory
  • Name of the light manufacturer
  • Number of Model
  • Visibility of the light in nautical miles
  • Date on which the light was type-tested
  • Specification of bulb used in compliance test

The full impact of this type of interference is not known and the Coast Guard is asking mariners who experience issues with reception due to LED interference to report their issues to the Coast Guard Navigation Center via their contact form by filing the report under the subject of Maritime Telecommunications. They would like to know the model of LED lighting and the radios that are affected as well as the distance between the lighting and the antennas of the affected radios. 

A Lesson on Navigational Light Visibility from Boaters University:

Interested in learning more about navigational lighting, what different light represent, and how to identify boats by their lighting pattern? Check out our course on Boaters University called Fundamentals of Seamanship: Navigational Rules. Use the promotional code PASSAGEMAKER for 20% off.

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