Gate marks, at the end of a run or downwind leg, have a number of advantages. They:

1. Reduce congestion at individual marks.
2. Give easier access to either side of the course.
3. Keep boats closer together on the same course.
4. Reduce the number of boats tacking through other boats on a downwind leg.

Fleet Racing: 

The two marks should each have their own distinct zones (the RRS define the size of each zone as 3 boat lengths) and should therefore be at least 7 boat lengths apart with a recommended distance of 8-10 boat lengths apart.

Match Racing: 

The two marks should have overlapping Zones. The RRS define the size of each zone as 2 boat lengths, and should therefore be 3.5 to 4 boat lengths apart.

Marks should be laid so there is no advantage attached to either. This often means that they are square to the sailing wind, but other tactical factors should be taken into account. At a good gate there will be an equal split of boats using each mark. Ideally the distance between marks should be measured with a laser Range finder.

A problem arises if a mark is missing and has not been replaced in a manner specified in RRS 34, which requires substitution with a similar mark or an object displaying flag “M”.

World Sailing Question and Answer 2009-034 says that with only one mark remaining there is no gate and the remaining mark has no required side. The consequence of this is likely to be abandonment of the race. To avoid this problem, race committees are recommended to specify a required side when only one mark of a gate is present, so that there will still be a mark with a required side. Boats would then round the remaining mark as any other single rounding mark.

The suggested SI to be inserted in the courses section is:

“If one of two gate marks is missing and has not been replaced as described in RRS34, then the remaining mark shall be rounded to port. This changes RRS 34.”

Gate marks may be used to align a run/beat by lifting one gate mark and moving it in the required direction. Normally RRS 33 would require signalling of any change.

However the following sailing instruction is now often used.

“Minor mark moves (up to approximately 100m) may be made without signalling the change. This changes RRS 33.”

Adopting gate marks does change the rules for the sailors.

Fleet Racing:

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.

Match Racing:

18.3 Tacking or Gybing

If mark-room for a boat includes a change of tack, such tack or gybe shall be done no faster than a tack or gybe to sail her proper course.

When an inside overlapped right-of-way boat must change tack at a mark to sail her proper course, until she changes tack she shall sail no farther from the mark than needed to sail that course. Rule 18.3(b) does not apply at a gate mark or a finishing mark and a boat shall be exonerated for breaking this rule if the course of another boat was not affected before the boat changed tack.