The Coast Guard announces Monday a change to the marine radio frequency that mariners must use to activate fog signals on navigable waterways of the Great Lakes.

Until the change takes effect on July 1, mariners are advised to use both the new and the old frequency.

Since the 1990s, mariners encountering decreased visibility have been able to activate fog signals on certain aids-to-navigation by tuning their marine radios to VHF-FM channel 79A (156.975 MHz) and keying their microphone five times.  Doing so activates the fog signals, allowing mariners to locate and identify the aids when they are hard to see, which results in safer transit.  The channel used for this purpose is being changed to channel 83A (157.175 MHz).

Mariners who wish to activate fog signals should key their microphones on both channels until July 1, when they should only do so on channel 83A.  This change is being made to shift radio traffic from channel 79A, a commercial channel, to channel 83A, a frequency owned and operated by the Coast Guard.

For more information, contact Doug Sharp, 9th Coast Guard District Aids to Navigation, at 216-902-6070.