Sailing in Fog
When the shoreline disappears, good seamanship becomes simpler, not louder. Slow the boat, sharpen the lookout, use the correct signals and make every decision with time in hand.
When visibility falls, routine matters more than courage
Fog is not dramatic in the way a gale is dramatic. There may be no breaking sea, no howling rigging and no obvious warning beyond the slow disappearance of the horizon. That is exactly why it catches sailors out. It tempts people to keep pressing on with the same pace, the same sail plan and the same level of attention. The wiser response is the opposite. In fog, the best skipper reduces complexity, buys time and keeps the boat easy to manage.
A strong fog routine begins with three ideas. First, keep a proper lookout by hearing as well as by sight. Second, proceed at a genuinely safe speed for the conditions, not the speed that felt comfortable ten minutes earlier. Third, treat electronics as support, not as a substitute for judgement. Official guidance on restricted visibility stresses that radar, AIS and VHF can help build the picture, but they do not remove the need for continuous lookout and cautious decision-making.
Essentials
Prepare before the white wall arrives
The smartest decisions in fog are often made before the fog reaches the boat. Check navigation lights, sound-signalling equipment, charting, compass and position. Think about the route ahead and ask whether there is a quieter option that avoids ferry tracks, harbour entrances, headlands and other tight decision points. If your yacht carries a radar reflector or radar target enhancer, make sure it is fitted correctly and as effectively as practicable. For small craft, that can materially improve the chance of being detected, but it is still not a guarantee.
Slow down early and make the boat simpler
Restricted visibility demands safe speed, and safe speed means more than taking the edge off. It means leaving enough time to identify a threat, decide what it is doing and respond without drama. If a vessel hears a fog signal apparently forward of the beam and risk has not been ruled out, the rules say speed should be reduced to the minimum at which the vessel can be kept on course, with all way taken off if necessary, and navigation continued with extreme caution. It also helps to simplify the boat itself: a balanced sail plan, less cockpit noise, one person clearly responsible for the helm, and another clearly responsible for lookout.
Use technology well, but never hand the whole job to it
Radar can reveal movement beyond visual range. AIS can identify many commercial targets. GPS and charting can keep your position honest. Yet none of these tools sees everything. Official guidance warns that AIS must not replace proper lookout, and that not all vessels carry it. Separate guidance on restricted visibility also notes that small craft may not show clearly on radar. The practical lesson is simple: keep cross-checking. Compare the screen with the compass, the depth, the chart and what the crew can hear. A good picture at sea is built from agreement between clues, not trust in one display.
Four fog rules worth remembering
In fog, the best sailor is usually the one who removes pressure earliest. These four rules are worth keeping in mind because they turn a vague feeling of caution into a clear working routine.
Proper lookout
By sight, by hearing and by all available means appropriate to the conditions.
Safe speed
Slow enough to take proper and effective action and to stop within a distance appropriate to the conditions.
Restricted visibility
This rule applies in or near restricted visibility, and when a target is detected by radar alone, avoiding action should be taken in ample time. So far as possible, avoid altering to port for a vessel forward of the beam, and avoid altering towards a vessel abeam or abaft the beam.
Sound signals
A sailing vessel underway should sound one prolonged blast followed by two short blasts at intervals of not more than two minutes. A power-driven vessel making way sounds one prolonged blast at the same interval. An anchored vessel normally rings a bell rapidly for about five seconds every minute, while smaller vessels that do not carry the prescribed bell signals must still make some other efficient sound signal.
FAQs
Do I need to switch on navigation lights in fog during the day?
Yes. If visibility is restricted, navigation lights should be shown even in daylight. Fog is not only a problem of darkness. It is a problem of detection. Proper lights help other vessels identify your presence earlier and reduce the risk of a late close-quarters situation.
Should I stay under sail in fog or start the engine?
That depends on the boat, the traffic around you and how much control you need. In some cases, a balanced sail plan is perfectly manageable. In others, motor-sailing or using the engine may give steadier speed, clearer manoeuvrability and better control. The right choice is the one that keeps the boat simple, predictable and easy to handle.
Is radar or AIS enough to keep me safe in fog?
No. Electronics are valuable, but they are only part of the picture. Not every vessel will appear clearly on radar, and not every vessel carries AIS. In fog, the skipper still needs a proper lookout, careful listening, sound judgement and continuous cross-checking between instruments, chart, compass, depth and what the crew can actually sense around the boat.
Does fog change the way I should trim or set sails?
Yes, in the sense that simplicity becomes more important than maximum performance. Fog is rarely the moment to carry an aggressive or complicated sail plan. A balanced, easy-to-handle setup helps the helm stay in control and leaves the crew with more time and attention for lookout, navigation and decision-making.