Specifically, the Cost Guard began advancing its sound signal devices back in 2015 and has scheduled to complete the final two installations in spring 2019.

The modernization of the equipment was conducted to replace the less efficient VM-100 fog detectors with a Coast Guard-designed, radio-controlled system.

In addition, the process also mitigated several 24/7 continuously sounding horns.


Therefore, mariners that now need foghorn assistance must activate the sound signal by using a marine VHF-FM radio. 

The MRASS device will enable mariners to energize the sound signal, on demand, by keying a standard VHF-FM radio five times consecutively on VHF channel 83A. The sound signal will then sound for 45-60 minutes following each activation.

Concluding, the MRASS is an economical part of the Nation's help to navigation system, providing a precise sound signal when the mariners need it.