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Rule 18.3:   Tacking when approaching a mark.

Every afternoon, wherever RC yachts gather to race, this Rule comes up over and over again. The situation is at the windward mark, which is to be rounded to port. Boats are approaching the mark on both tacks – one approaching on starboard and the other on port tack.

The boat on port must perform a tack to round the mark, and the boat on starboard is on the layline. The boat on port completes her tack within the 4 boat length zone. What are the rules?

18.3 Tacking When Approaching a Mark

If two boats were approaching a mark on opposite tacks and one of them changes tack, and as a result is subject to rule 13 in the zone when the other is fetching the mark, rule 18.2 does not thereafter apply. The boat that changed tack

(a) shall not cause the other boat to sail above close-hauled to avoid her or prevent the other boat from passing the mark on the required side, and

(b) shall give mark-room if the other boat becomes overlapped inside her.

The Tacking Boat.

The boat approaching on port tack:

  • Must keep clear whilst tacking. (Rule 13)
  • Must not cause the starboard boat to sail above close hauled at any time until the mark is cleared. (Rule 18.3a)
  • Must not cause the starboard boat to sail the wrong side of the mark. (Rule 18.3a)
  • Must give mark-room if the other boat becomes overlapped on the inside. (Rule 18.3b)

The Non-tacking Boat.

The boat approaching the mark on starboard tack:

  • Must keep clear if astern or to windward. (Rules 12 and 11)
  • May establish a late, inside overlap even if she was clear astern (Rule 18.3b) but must give room for the windward boat to keep clear whilst sailing to the mark.  (Rule 16.1)

TACTICS – or how to handle this situation…..

The Tacking Boat:

Despite the temptation to tack and round the mark ahead of the starboard boat, a port tack boat which can cross the starboard boat should stay on port and cross, allowing the starboard boat to round the mark first. By electing this course of action, the port tack boat has given up one or two boat lengths of distance and avoided a sure losing protest.

Had the port tack boat tacked right at the mark and directly in front of the starboard tack boat, she would have opened herself to a no win situation under Rule 18.3. All the starboard boat has to do is put her bow up above a close hauled course to protest under 18.3 (a) or dive to leeward to claim mark-room under 18.3 (b). As long as there is no question that the port tack boat completed the tack inside the zone, her chances of prevailing in a protest hearing are close to non-existent.

The Non-tacking boat:

If the starboard boat is sailing above the layline, and has her sheets slightly loosened, she may be able to avoid the tacking boat by simply sailing up to a close hauled position. If this is the case, then the tacking boat has not broken Rule 18.3. The Rule is only broken when the starboard boat is forced to sail above close hauled at any time whilst at the mark.

  • If approaching a windward mark in such a situation, a starboard boat might elect to sail low early, and come up to a close hauled position on the lay line prior to the port tack boat coming close. This gives the port tack boat fewer options.

Rule 18.3 only applies to a boat inside the zone that is fetching the mark. If the starboard tack boat is not fetching the mark and will be forced to tack to round the mark, these rules do not apply. In this scenario, take away the mark, and the normal racing rules of sailing apply.

If the port tack boat completes her tack inside the zone, and the starboard boat is going to become overlapped, the starboard boat is able to select whether she wants to pass to windward or leeward of the boat that tacked.  The boat that tacked does not have the protection of Rule 18.2 which talks about establishing an overlap prior to reaching the zone. Rule 18.2 does not apply when a boat completes a tack inside the zone.

  • If the starboard boat passes to weather of the tacking boat, Rule 11 applies, and the windward boat must keep clear, despite the fact that the other boat tacked in the zone. The tacking boat breaks Rule 18.3 only if the non-tacking boat must sail above close-hauled (ie the jib luffs when close hauled) in order to fulfil the requirements of Rule 11.
  • If the starboard boat elects to create the overlap to leeward, then two things happen:
  1. oThe non-tacking boat must be given mark-room and not forced to sail the wrong side of the mark and
  2. oThe non-tacking boat must give room for the windward (tacking) boat to keep clear whilst sailing to the mark. Once at the mark, the leeward boat can sail her proper course.

What are the implications of “sailing the proper course” whilst at the mark?

If a boat is taking mark-room to which she is entitled, is sailing her proper course and breaks a rule of Section A, or Rule 15 or 16, she will be exonerated from that breach under Rule 18.5b. This means that whilst the non-tacking boat must give room for the other boat to keep clear when sailing to the mark, this requirement switches off once the non-tacking boat is at the mark.

What happens if there is contact with the mark?

If a boat entitled to mark-room is forced to make contact with the mark by the actions of the tacking boat, Rule 64.1c exonerates the” in-the-right” boat, and the “at fault” boat must complete a penalty.


Although most sailors understand that approaching a mark on the port lay-line is not a good idea, it happens even to the best skippers. An unexpected lift, a missed call or being driven out to the left of the course by a windward boat are some of the ways we can end up in that unenviable spot. However the real problems start when you enter the zone on port tack because tacking in the zone is the equivalent of leading with your chin in a boxing match.

In the event that you are able to round clearly from port, then none of this is a concern, but too often in Radio Sailing, skippers make a misguided judgement that they will be able to complete the rounding manoeuvre from port cleanly. This boils down to judgement being clouded by greed!

Try to get into the habit of crossing when you can, and tacking to weather of the approaching starboard boats. Making an early judgement about whether to cross in front or astern an approaching starboard boat will help. Far too frequently, skippers leave their decision too late, resulting in a crash tack into the leeward bow of the starboard boat, boats locked together and very frustrated skippers. The alternative might involve sacrificing a couple of boat lengths, but this is insignificant in comparison to the potential loss when you get it wrong.

Understanding the rules associated with the port tack approach to a windward mark will save a whole lot of grief for all concerned!