Operating in Fog
What Are Conditions of Limited Visibility and What Are the Signaling Requirements?
The USCG defines “limited visibility” in the Navigation Rules as “…any condition in which visibility is restricted by fog, mist, falling snow, heavy rainstorms, sandstorms, smoke, or any other similar causes.” Note that darkness is not considered a condition of limited visibility as far as operating and sounding rules are concerned.
It is required that all vessels sound “limited visibility” signals in repeating patterns approximately every two minutes. Vessels over 12 meters in length have specific blast patterns that are required. For vessels under 12 meters, the same blast patterns are recommended, but only an “… efficient sound signal at intervals of not more than 2 minutes” is required.”
FogMate automates signaling compliant with these requirements. When
sound signals are used properly, one can determine not
only that another vessel is in close proximity, but can also determine the vessel type, and whether the vessel is underway or is stopped.