Fog

Fog is a low cloud of microscopic water droplets at the sea surface that reduces visibility for vessels, typically to less than 1 nautical mile. At sea it is commonly produced when warm, moist air moves over cooler water, or when moist air cools overnight in sheltered bays and estuaries.

For boaters, fog turns a routine passage into an instrument-navigation task: slow down, post a proper lookout, sound the required signals, and keep clear of traffic, shoals, and harbour entrances. Safe operation depends on accurate position fixing with GPS, collision awareness from Radar, and tracking nearby vessels with AIS.

Forecasting fog requires attention to air temperature, sea temperature, humidity, wind strength, and overnight cooling. PredictWind forecasts, GRIB downloads in the Offshore App, and map layers such as Air Temp Maps help crews identify periods when visibility may deteriorate and adjust departure timing, routing, or watchkeeping plans.