Last month, I looked at two boats going downwind towards the leeward mark, both on port. This month, one of the two is on starboard. Again, the diagram shows them with spinnakers, but the issues are the same in a whitesail race.
White is sailing slightly high of a run on port. Blue is a little further behind, but is on starboard. The two boats are converging slowly. It is quite possible that White does not even realize that Blue is on starboard as looking from ahead, it may not be obvious. The two boats slowly converge from position 1 to position 3. At position 4, White decides to head up to the mark. As we saw last month, if Blue was on port, this would be quite legal. Since Blue is on starboard, it is not. Sometimes a boat in White’s position will yell at Blue to “sail your proper course.” There is no rule, at this point, that requires Blue to sail her proper course; White is out of luck. The only rule that applies here is rule 10, so White on port has to keep clear of Blue on starboard.
At position 6, after White has kept clear, she gets to the zone. Now the rules change a little. The two boats are overlapped, so Blue is entitled to mark-room. Blue is the inside boat and is also the right-of-way boat since she is still on starboard. Her proper course is to gybe to round the mark. Blue does now have a limitation. Rule 18.4 says that she can sail no further from the mark than her proper course until she gybes. Once rule 18 starts to apply – which, according to rule 18.1 is when the first boat gets to the zone – rule 18.4 limits Blue to her proper course. Blue is not allowed to keep going to leeward and drive White away from the mark.
At position 7, Blue gybes to comply with this obligation. She is now no longer on starboard tack. She is a windward boat on port tack and therefore no longer right-of-way.
Rule 18.4 stops applying. Blue is now the give-way boat. She is still entitled, however, to mark-room. Just as White has had to give her room to sail to the mark, White must still give room to Blue to sail her course until Blue is around the mark.
Mark-Room Room for a boat to leave a mark on the required side. Also,
(a) room to sail to the mark when her proper course is to sail close to it, and
(b) room to round the mark as necessary to sail the course.
However, mark-room for a boat does not include room to tack unless she is overlapped inside and to windward of the boat required to give mark-room and she would be fetching the mark after her tack.
Room The space a boat needs in the existing conditions, including space to comply with her obligations under the rules of Part 2 and rule 31, while manoeuvring promptly in a seamanlike way.
Zone The area around a mark within a distance of three hull lengths of the boat nearer to it. A boat is in the zone when any part of her hull is in the zone.
10 ON OPPOSITE TACKS
When boats are on opposite tacks, a port-tack boat shall keep clear of a starboard-tack boat.
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….
18.2 Giving Mark-Room
(a) When boats are overlapped the outside boat
shall give the inside boat mark-room, unless rule
18.2(b) applies.
(b) If boats are overlapped when the first of them reaches the zone, the outside boat at that moment shall thereafter give the inside boat mark-room. If a boat is clear ahead when she reaches the zone, the boat clear astern at that moment shall thereafter give her mark-room.
(c) When a boat is required to give mark-room by
rule 18.2(b),
(1) she shall continue to do so even if later an overlap is broken or a new overlap begins;
(2) if she becomes overlapped inside the boat entitled to mark-room, she shall also give that boat room to sail her proper course while they remain overlapped.
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