In the last two chapters we learned what should happen when two sailing vessels approach one another and there is a risk of collision. One of them has to give way and the other has to stand on. Our way to remember was: “Sail left has right!” and if both have the wind from the same side: “Leeward before windward!”
But in one specific case the rules above do not apply: when overtaking. That is the case when one boat comes from behind and is faster. The rule there is: “Any vessel overtaking any other shall keep out of the way of the vessel being overtaken.” That means the overtaking boat keeps clear. (Indication of source: United States Coast Guard, Navigation Rules)
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Which side is the best to overtake a sailboat on … ? Just think about it. We overtake on windward side if possible. If we try on the leeward side we will get in the wind shadow of the other boat and we cannot pass it.
The red boat on figure 126 is approaching the blue vessel from an angle of more than 22.5 degrees abaft its beam. Abeam is regarded as an angle of 90 degrees to the keel line. (an imagined line from the middle of the bow to the middle of the stern.) An overtaker is now coming up 22.5 degrees behind abeam. No matter if from starboard or from port side. If we subtract 22.5 degrees from the left side and from the right side of 180 degrees an area of 135 degrees remains. In the darkness we would only see the stern light of the boat in front of us. But in daylight it is not so easy to determine. So: “When a vessel is in any doubt as to whether she is overtaking another, she shall assume that this is the case and act accordingly.” (Indication of source: United States Coast Guard, Navigation Rules)
When during the overtake the bearing changes and the overtaker leaves the area of 135 degrees it is nevertheless still regarded as overtaking. This stays in place until the other boat is finally past and clear. Till then the overtaker has to keep clear.
So we learned: Sail left has right, leeward before windward, the overtaker keeps clear and the evasion manoeuvre has to be done in ample time. It has to be clearly identifiable and determined.
All chapters: Technical Terms | The theory behind sailing |Close-hauled | Beam reach | Broad reach | Sailing downwind | Tacking | Beating | Quick-turn | Sailing up head to wind | Man overboard | Jibing | Heaving-to | Leaving the dock | Berthing | Rules of the road 1 | Rules of the road 2 | Rules of the road 3 | Reefing | Capsizing