Safety Tips For Boating in Fog

Boating in foggy conditions is unnerving and dangerous, but it’s something every boater should be prepared for. Knowing what to do when you suddenly find your boat engulfed in fog is crucial for all boaters. 

Because boating safety is of the utmost important, and navigating a boat in very limited visibility is incredibly dangerous, here are some tips for boating safely in foggy conditions.

What Causes Fog?

There are several different types of fog, including convection fog and ground fog, but boaters should concern themselves mostly with advection fog.

“Advection” refers to the horizontal movement of the air. This type of fog is created when warm, moist air moves over a cool surface, which condenses the moisture within the air to create fog. Coastlines and the shores of larger lakes are the perfect breeding grounds for advection fog, as warm “land air” moves out over the cool body of water. 

Advection fog often happens at dawn or dusk, but can form at any time of day or night. It can also form under cloudy conditions and in moderate to higher winds, making it much less predictable than other adverse weather conditions. 

Fog Hazards While Boating

Fog causes a reduction or almost complete loss of visibility. Its density and effect on visibility varies, but in maritime terms fog is considered “dense” when visibility is reduced to 1 mile. 

Maritime forecasts use the following standardized visibility definitions:

• Good visibility is greater than 5 nautical miles
• Moderate visibility is between 2-5 nautical miles
• Poor visibility is between 1/2-2 nautical miles
• Very poor visibility is less than 1/2 nautical miles

A reduction in visibility produces several hazards for a recreational boater. Moving off course is one of them. With no landmarks in sight, it’s almost impossible to maintain an intended heading. Getting lost is another, as having limited visibility is disorienting, and the inability to maintain the correct heading can quickly lead to not knowing where you are. 

Gear and Equipment to Use in Foggy Conditions

The US Coast Guard requires all recreational boats to carry certain sound-producing devices to alert nearby vessels of your position in foggy conditions.

Fog-related safety gear and equipment you should carry onboard includes:

• One properly-sized personal flotation device/life jacket for every person onboard.
• A compass and map to remain on roughly the right course.
• A VHF marine radio, which has a greater range than a cellphone, is monitored by the USCG and provides direct vessel-to-vessel communication. 
• A depthfinder or fishfinder to show you the depth beneath the hull so you don’t run aground or hit submerged obstacles. Depthfinders are more effective at relaying details about the bottom, but a fishfinder will do in a pinch.
• A high-power searchlight to alert other vessels of your presence.
• A marine radar to alert you of nearby vessels in fog. Radars aren’t cheap and not every boat has one, but if you boat often, consider investing in one. 
• Sound-producing devices such as horns and whistles, or a permanently installed ship’s bell or horn.

NOTE: The USCG has set out how sound-producing devices should be operated in 33 CFR § 83.35 - Sound Signals In Restricted Visibility (Rule 35).

Tips for Boating in Fog

If you find your boat engulfed in fog, stay calm so that you can make prudent decisions and reassure other people onboard. Make sure everyone onboard including yourself puts on their life jacket or PFD, and follow these next tips for getting through the fog safely:

Visibility in Fog

Switch on all of your boat’s lights, especially searchlights to alert other vessels of your location. Maintain a 360-degree lookout for other vessels or obstacles. If you have enough people onboard, assign them as lookouts on each side of your boat until the fog lifts.

Sounds

Get any air horns or whistles you have ready, or have someone man the ship’s bell or horn. Sound the devices at regular intervals to alert other vessels of your presence, and listen for sounds coming from other boats and navigational structures or buoys. 

Navigation

Slow your speed to the point you’re just making headway without coming to a complete halt. This gives you time to react and maneuver if you suddenly see an object in your path, and prevents you from travelling too far off course. Chart your progress by marking your current location on a map or electronic plotter. Continue logging your speed and course as you go. If your boat has a radar, depth finder or GPS chart, use them to gather information about nearby vessels, the depth beneath your hull and any other useful data.

Eventually the fog should lift and if you followed these tips you, your boat and your passengers will have come through it without incident. Remember to read and memorize the Coast Guard’s rules regarding Sound Signals In Restricted Visibility, and take it in stride the next time you find your boat surrounded by fog.