Analyzing an Unusual Mark Trap

Assume you're approaching a mark, and you have and inside overlap. You hail for room and the ouside boat replies "No way! I neeed room to pass the mark on the wrong side." What would you do? Dick Rose explains in our June 2006 issue.


Elizabeth Wishe

If you really want to learn the racing rules, try team racing. In one close team race you’ll encounter more knotty rule situations than you’re likely to experience in a season of fleet racing. I received a question from umpire Bryan McDonald about a mark rounding incident that will really test your knowledge of the Part 2 rules-especially Rule 18, Rounding and Passing Marks and Obstructions.The question arose after an intercollegiate team race. Teams from Boston and New York were racing. The fleet of Vanguard 15s was beam reaching on port tack approaching a mark they were required to leave to starboard. The mark was a small round plastic buoy. The next leg was a run directly downwind. The incident involves Derek and Alex on the New York team, and Manny on the Boston team.As the incident begins, Derek is several lengths clear ahead of Manny and Alex, who are overlapped, Manny to windward of Alex. The wind is steady and moderate, and in such conditions boats become “about to round or pass” a mark or obstruction when they enter its two-length zone (see Rule 18.1 and ISAF Cases 84 and 94).As shown in the first diagram, just after Derek’s bow enters the two-length zone around the mark, he sets a mark trap by backing his sail to stop his boat and then waiting for the other two to catch up. Both Manny and Alex must keep clear of Derek under Rule 12, and for that reason, Derek is an obstruction to both of them (see the definition Obstruction). At position 1, they enter the two-length zone around Derek and, because Manny and Alex are both about to pass on the same (leeward) side of Derek, Rules 18.2(a) and 18.2(b) begin to apply to them and continue to apply until they have passed Derek (see Rule 18.1). Alex complies with Rule 18.2(a) by giving Manny room to pass Derek.That was the easy part! Now things begin to get interesting. At position 2 (see the second diagram) Manny reaches the two-length zone around the mark. Alex hails Manny for room to round the mark to starboard as is required to sail the course, and at the same moment Manny hails Alex for room to pass the mark to port in order to avoid fouling Derek. Tilt! Should Alex ignore Manny’s hail or vice versa?To get our heads around this situation, let’s start by listing the rules that apply at position 2:Rule 18.2(c)’s first sentence requires both Manny and Alex to keep clear of Derek. In addition, because they both have become overlapped inside Derek, that same rule’s third sentence warns them that neither of them is entitled to room to pass between Derek and the mark.Rule 11 requires Manny to keep clear of Alex unless that rule conflicts with part of Rule 18 (see the preamble to Section C).Under Rule 31.1 all three boats must not touch the mark.Derek is permitted, as any boat always is, to trim his sails to increase his speed through the water, and Rule 18.2(d) permits him to change course as rapidly as he wishes to round the mark.Because both Manny and Alex must keep clear of Derek and because Rule 18.2(d) permits Derek to “shut the door” between himself and the buoy as rapidly as he pleases, it is not safe for either Manny or Alex to enter the area labeled “Danger Area” in the second diagram. At position 2, Manny and Alex are blocked by Derek’s presence from passing to windward of the Danger Area. Their only choice is to pass to leeward of it.The buoy is virtually on a corner of the Danger Area and, therefore, at position 2 it is an object that can be safely passed by Manny and Alex on only one side (its leeward side). If you read the second sentence of the definitionObstruction, you will see that, even though the buoy is so small that it would normally not be an obstruction, in this situation it is an obstruction for Manny and Alex because it is not safe for them to pass to windward of it.Manny and Alex were overlapped when they came within two hull lengths of the buoy. Therefore, if Alex and Manny were to pass to leeward of the buoy, Alex would be required by Rule 18.2(a) to give Manny room to pass to leeward of it, and Alex would also be required to comply with Rule 18.2(b) until they have passed it.The buoy is, of course, a mark that the boats must eventually leave to starboard in order to sail the course as required by Rule 28.1. However, there is no rule that says when they must leave it to starboard. If from position 2 Manny and Alex were to sail directly to round the mark to starboard, then Manny would be required by Rule 18.2(a) to give Alex room to round and Manny would also be required to comply with Rule 18.2(b).So, at position 2 whose hail should govern? Must Manny give Alex room to round the mark as they would do if Derek were not present? Or must Alex give Manny room to pass to leeward of it?The answer can be found in Rule 18.1. It is clear from Manny’s unusual hail that he is not about to round the mark in the normal way. Instead he is about to leave it to port in order to avoid entering the Danger Area and to avoid breaking Rule 18.2(c) by failing to keep clear of Derek. If Manny leaves the buoy to port then Alex, if he is to avoid contact with Manny, must also leave it to port. Therefore, Manny and Alex are both about to leave the buoy, an obstruction, on the same side (as shown in the third diagram). Manny was overlapped inside Alex when they came within the buoy’s two-length zone. For those reasons, Alex must give Manny room to pass the buoy on his port side.At position 3 Manny manages to avoid contact with Alex by a matter of inches, but he touches the buoy. In addition to being an obstruction, the buoy is also a mark. ISAF Team Racing Call H2 states explicitly, “It is not seamanlike to hit a mark.” When Manny hits the mark there is just a tiny distance between the end of his boom and Alex’s topside. Therefore, Alex failed to give Manny room to pass the obstruction-i.e., the space Manny needed to carry out the maneuver of passing the obstruction in a seamanlike way (see the definition Room).The bottom line: Alex breaks Rule 18.2(a) by failing to give Manny room to pass the buoy, an obstruction that those two boats were leaving on the same side. Manny breaks Rule 31.1 by touching the buoy because it is also a mark. Alex should be penalized, but Manny should not. Under Rule 64.1(b) Manny should be exonerated because he was compelled to break Rule 31.1 by Alex’ breach of Rule 18.2(a).Phew! I warned you this would be a knotty one.If you’d like to learn more? The Call Book for Team Racing for 2005-2008 is an excellent resource that contains many analyses of mark-rounding situations that crop up in team races. It is available to download for free from the International Sailing Federation’s website ( If you would like to test yourself by applying the rules to situations similar to the one discussed in this column, I recommend you read the Questions in Team Racing Calls H1 and H2, but cover up the Answers. Try to work out the answers on your own before reading the answers ISAF provides.E-mail for Dick Rose may be sent to [email protected].


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