Racing Rules explained – Rule 18

Rule 18 – Mark Room

Rule 18 is again one of the more complicated rules within our sport. It is broken down into multiple sections to determine the following:

  • When does it apply? (18.1)
  • How to give mark room (18.2)
  • Manoeuvring at a mark and how mark room is affected (18.3 and 18.4)


  • Mark – An object that a boat must leave on a specified side. An anchor line or an object attached to a mark is not part of it.
  • Zone – The zone is a determined distance around a mark. This can be different depending on your sailing instructions. Default length is set at 3 boat lengths, however, this changes for match and teams racings. Remember to check your sailing instructions.

Rule 18 opens by discussing when the rule does or does not apply:

Rule 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

(a) between boats on opposite tacks on a beat to windward,

(b) between boats on opposite tacks when the proper course at the mark for one but not both of them is to tack,

(c) between a boat approaching a mark and one leaving it, or

(d) if the mark is a continuing obstruction, in which case rule 19 applies.”

The rule does not “turn on” until one of the boats is in the zone. When sailing to a windward mark or the finish line, the rule does not apply when two boats are on opposite tacks.


Rule 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.

(d) Rules 18.2(b) and (c) cease to apply when the boat entitled to mark-room has been given that mark-room, or if she passes head to wind or leaves the zone.”

(e) If there is reasonable doubt that a boat obtained or broke an overlap in time, it shall be presumed that she did not.

(f) If a boat obtained an inside overlap from clear astern or by tacking to windward of the other boat and, from the time the overlap began, the outside boat has been unable to give mark-room, she is not required to give it.”

The key to getting Rule 18.2 right, is to remember the exact moment when the first boat enters the zone. If you are overlapped, you must give mark room to any inside boats that are overlapped, regardless of whether the overlap is maintained.

The next two parts to Rule 18 refer to when boats must perform a tack or gybe to get around the mark. The key note for this next section to remembering the proper course for both yourself and other boats.


Rule 18.3 – Tacking in the Zone

“If a boat in the zone of a mark to be left to port passes head to wind from port to starboard tack and is then fetching the mark, she shall not cause a boat that has been on starboard tack since entering the zone to sail above close-hauled to avoid contact and she shall give markroom if that boat becomes overlapped inside her. When this rule applies between boats, rule 18.2 does not apply between them.”

If you tack from port to starboard in the zone and are fetching the mark, you can’t cause boats coming in on starboard to sail above close-hauled. This is true even if you complete your tack clear ahead of the starboard boats.


Rule 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.”

Again, remember your proper course is to a mark. This does not change if you have a problem with your drop!


CYCA Principal Sponsor

CYCA Official Sponsors

CYCA Youth Sailing Academy Sponsors and Supporters

Thank you! Your subscription has been confirmed. You'll hear from us soon.
CYCA weekly newsletter