James Stevens addresses a concern raised by a reader of Yachting Monthly, who inquires how to prevent a collision in fog while operating a yacht.
Martin and Barbara, accompanied by their teenage son, Rob, have sailed from the Solent to the Channel Islands in their 10-meter yacht. Rob, having crewed frequently, is already more adept at using the new electronic chart system and AIS than his parents are. The setup lacks radar.
During their journey to Guernsey, the weather was clear with good visibility, allowing them to see ships in the shipping lanes both with their eyes and on the chart. They are now making their return trip. The forecast upon departure indicated possible fog patches, but in Guernsey, visibility was approximately 2-3 miles with light winds.
Since Martin and Barbara need to resume work, they believed that with the AIS, they could navigate the shipping lanes under moderate visibility.
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Once they entered the shipping lanes, visibility decreased to less than half a mile. They navigated carefully across, and thanks to the AIS, they managed to exit the lanes and are now cruising home at 6 knots. After a stressful experience in the shipping lanes, Martin and Barbara feel exhausted, so they head below to rest, activating the autopilot and leaving Rob on watch with his eyes on the screen.
About 30 minutes later, they hear five blasts. Martin rushes on deck to find a small coaster slowly motoring toward them on a collision course from the starboard side.
What steps should Martin take now? Why hasn’t the coaster appeared on the screen? Is it violating SOLAS regulations? If the coaster has radar, why hasn’t it changed course to go behind the yacht?
How can a yacht collision be avoided in fog?
Martin should reduce speed and make a quick, decisive turn to starboard. He needs to closely monitor the coaster, as now that both vessels can see each other, the coaster may begin a port turn to pass behind the yacht.
Rob is skilled with the electronic chart, but in this scenario, a vigilant lookout by sight and sound is crucial. The coaster, unless carrying passengers, is not required under SOLAS to have AIS if it weighs less than 300 tons. It would typically be equipped with radar.
AIS is incredibly useful for avoiding collisions, but can it be depended upon for a Channel crossing in fog?
The watchkeeper on the bridge may have detected the yacht via radar. Before visual contact, the coaster is right to slow down and avoid making a port turn. The rules for collision avoidance in restricted visibility differ from those applicable when vessels are within sight of each other.
AIS is a very valuable navigation tool. Identifying ships on the electronic chart and recognizing their course and speed greatly aids the navigator. AIS also transmits additional information such as the vessel’s name, call sign, and MMSI number.
However, it provides only part of the overall picture. Many small vessels, including numerous yachts, do not send AIS signals, meaning these boats won’t appear on the electronic display if there is no radar.
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