The last two articles looked at boats heading downwind and things to watch out for. At the end of the leeward leg is the leeward mark. Many leeward marks these days are gates. With a gate, boats can choose which of two marks to go around.
In the diagram Red and Green approach the mark on the left side of the diagram (2S) which they will leave to starboard. Red is on port tack. Green is on starboard tack. Green has forgotten that mark-room applies between boats on opposite tacks as long they are not at the weather mark. We see this by looking at rule 18.1. Rule 18 as a whole is the mark-room rule. Rule 18.1 describes when the rest of rule 18 applies. It starts out by saying that it applies between boats that are both required to leave a mark on the same side. All 4 boats in the diagram are required to leave 2S to starboard and 2P to port. It applies when they are both in the zone. From position 2 onwards Red and Green are in the zone. The rest of rule 18.1 lists exceptions. 18.1(a) and 18.1(b) say that rule 18 does not apply between boats on opposite tacks at a windward mark. In our diagram Red and Green are on opposite tacks but not on a beat to windward so 18.1(a) does not apply. Neither of them will have to tack to sail their proper course at the mark so rule 18.1(b) does not apply. Rule 18.1(c) and 18.1(d) refer to different situations. Since initial part of rule 18.1 applies and the exception do not, mark-room does apply between the two boats. Red is entitled to mark-room and Green has to sail further from the mark to give Red that room. Red is not right-of-way so while she is entitled to room, she cannot just keep sailing straight. She has to sail around the mark.
On the other side of the diagram Blue and Yellow are also approaching a mark, this time 2P. Yellow is also right-of-way so she does not have to gybe at the mark. If mark 2P was a standalone mark then yellow would be required by rule 18.4 to gybe. Rule 18.4 however does not apply at gate marks. Blue is in a difficult position. She would be better to have slowed down and gone behind Yellow or she might have to sail around 2S.
18 MARK-ROOM
18.1 When Rule 18 Applies
Rule 18 applies between boats when they are required to leave a mark on the same side and at least one of them is in the zone. However, it does not apply
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between boats on opposite tacks on a beat to windward,
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between boats on opposite tacks when the proper course at the mark for one but not both of them is to tack,
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between a boat approaching a mark and one leaving it, or
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if the mark is a continuing obstruction, in which case rule 19 applies.
18.4 Gybing
When an inside overlapped right-of-way boat must gybe at a mark to sail her proper course, until she gybes she shall sail no farther from the mark than needed to sail that course. Rule 18.4 does not apply at a gate mark.
© Copyright 2017 Andrew Alberti