Navigating in fog

Since navigating in fog can present serious challenges, boaters need to have a plan to deal with fog before it occurs.

“Storms announce their arrival with bravado—a fanfare of wind, rain or snow. Fog arrives stealthily, and oftentimes quickly, with silent restraint,” said Ronald Kessel, past Marine Environment Committee chair of United States Power Squadrons, America’s Boating Club. “There is no other weather event where your safety is so dependent on other boaters or where your responsibility to other boaters is greater.”

Fog restricts visibility, making it difficult or impossible to see and be seen by other boaters with the naked eye. When you can’t see the horizon, you can lose your bearings and experience temporary disorientation. Fog also dampens some sound frequencies, making it difficult to discern the direction from which sound is coming. These factors increase the risk of collision, grounding and injury.

What to do in restricted visibility

Kessel advises that any prudent boater should delay getting underway when fog is present or forecast. However, if you’re caught in fog, you can take three immediate actions to stay safe:

Reduce speed to be able to stop within half the visible distance.
Ensure everyone on board is wearing a life jacket, preferably a high-visibility vest equipped with reflective tape, a whistle and an EPIRB.
Make sure your running lights are on: You want to be seen.

Your lookouts should be vigilant, looking and listening for nearby vessels and buoys. Reducing your own engine noise momentarily can help. You and your crew should be familiar with the sound signals—horns and bells—used to warn others around you of your proximity, relative bearing, and whether you are underway or anchored.

Periodically fix your position using your GPS or a chart, and use your compass to navigate in the right direction. Alternatively, stop until the fog lifts and do all you can to ensure you are in a safe location—out of shipping channels—where other boat traffic is unlikely.

Using your equipment to navigate

Marine electronics provide vital support:

Your VHF marine radio helps you to monitor NOAA weather forecasts about changing fog conditions and communicate with other boaters.
Radar helps you know about other vessels, objects and dangers around you; and radar reflectors make your vessel’s target image brighter and bigger on another boat’s radar monitor.
AIS helps you and other AIS-enabled vessels transmit and receive data about vessel identity, location and closest points of approach. One of the advantages of AIS is that, unlike radar, AIS makes a full-size target image on the other boat’s monitor regardless of the size or type of boat transmitting the AIS data.
Fish finders and sonar help you reconfirm your position against charted depths.

All contribute to vessel readiness, safe navigation and seamanship—provided you and your crew know how to use them.