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How much “Room” is “Mark-Room”?

This subject is the cause of quite a few discussions (read ‘arguments’) at lakeside. The Racing Rules of Sailing do not specify or regulate specific distances, as the Rules are written for all types of boats, from dinghies to maxis, windsurfers and multihulls as well as radio controlled yachts. All these craft handle differently, so the Racing Rules of Sailing are general in nature.

The question of “How much room do you need?” is very commonly heard amongst Radio skippers. The answer depends on the situation - as you will see.

The Rule which gives an inside boat ‘Mark-room is Rule 18.2, which reads (in part) as follows:

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.

The answer to the question can be better understood by reading the definitions of both ‘Mark-Room’ and ‘Proper Course’.


Mark-Room Room for a boat to sail to the mark, and then room to sail her proper course while at the mark. However, mark-room does not include room to tack unless the boat is overlapped to windward and on the inside of the boat required to give mark-room.

Proper Course
A course a boat would sail to finish as soon as possible in the absence of the other boats referred to in the rule using the term. A boat has no proper course before her starting signal.


Is a boat entitled to mark-room allowed to make a tactical approach/tactical rounding (often called a “wide in, tight out”) of the mark or is boat entitled to mark-room only allowed to a seamanlike approach/rounding?


Mark-room is split into two aspects:

Room to sail to the mark

  1. (i)If the boat entitled to mark-room is the keep-clear boat, then room to sail to the mark is neither room to sail her proper course (if extra room is needed for a proper course approach), nor is it room to make a more tactical rounding.
  2. (ii)If the boat entitled to mark-room has right of way, she is free to sail any course within the limitations of the rules of Part 2, Section B, and, if it applies, rule 18.4 (the reasonable doubt rule).

Room to sail her proper course while at the mark

  1. (i)A boat may sail her proper course from the time she is at the mark and while she rounds or passes the mark and until she no longer needs the mark-room. This course would therefore be the one the boat would sail in the absence of the other boats referred to in the rule.

Therefore, only an inside right-of-way boat that is entitled to mark-room may make a tactical approach and a tactical rounding. However, if the inside right-of-way boat is subject to rule 18.4, then, until she gybes, she may not sail farther from the mark than needed to sail her proper course. Note that a tactical rounding may be wider than a proper course rounding.

The ISAF Case Book 2009-2012 also has something to say on the question, particularly in relation to the situation where the inside boat is not the right-of-way boat.


Definitions, Mark-Room

Definitions, Proper Course

Definitions, Room

The amount of space that a right-of-way boat obligated to give mark-room to an inside overlapped boat must give at the mark depends on the inside boat’s proper course in the existing conditions.



When a right-of-way boat is obligated to give mark-room to an inside boat that overlaps her, what is the maximum amount of space that she must give? What is the minimum amount of space that she must give?


The possible answers vary widely. To suggest the extremes, they might be:

1. as a minimum, enough room with sails and spars sheeted inboard for the hull to clear by centimeters both the outside boat and the mark or obstruction;

2. as a maximum, all the room the inside boat takes, setting her course as far abeam of the mark as she wishes.

Neither is correct.



As the definition Mark-Room states, while the inside boat is at the mark the outside boat must give her room to sail her proper course. If the overlapped boats are on the same tack, mark-room includes room to tack.

According to its definition, ‘room’ in this case is the space needed by an inside boat, which in the existing conditions is handled in a seamanlike way, to sail her proper course while at the mark. The inside boat’s proper course is the course she would sail to finish as soon as possible in the absence of the outside boat.

This may entitle the inside boat to more space than she needs for a seamanlike rounding. For example, her proper course may be a track that takes her farther from the mark as she rounds than a seamanlike rounding would, so that her speed is not reduced by the tightness of her turn.

The important thing to understand is that according to the definition Mark-Room, an inside overlapped boat that is required to keep clear of the outside boat is not entitled to sail her proper course while sailing to the mark; she is only entitled to sail her proper course after she is at the mark.

The term ‘existing conditions’ deserves some consideration. For example, the inside one of two dinghies approaching a mark on a placid lake in light air will need relatively little space beyond that required for her hull and properly trimmed sails. At the other extreme, when two keel boats, on open water with steep seas, are approaching a mark that is being tossed about widely and unpredictably, the inside boat may need a full hull length of space or even more to ensure safety.

The other aspect of existing conditions which applies to Radio Sailing is the location of the mark with respect to the control area. At a mark which is right in front of the skippers on the bank, the room required will be much less than at a mark set at a distance from the bank.

The phrase ‘in a seamanlike way’ applies to both boats. First, it addresses the outside boat, saying that she must provide enough space so that the inside boat need not make extraordinary or abnormal manoeuvres to sail her proper course while at the mark. It also addresses the inside boat. She is not entitled to complain of insufficient space if she fails to execute with reasonable efficiency the handling of her helm, sheets and sails while sailing her proper course.

The concept of what is ‘seamanlike’ is also a challenge. Some skippers with excellent boat handling skills might have a very different idea about ‘seamanlike’ to a novice skipper. Clearly this difference leads to issues at many regattas. Case 103 gives a guide to this question:

CASE 103

The phrase ‘seamanlike way’ in the definition Room refers to boat-handling that can reasonably be expected from a competent, but not expert, crew of the appropriate number for the boat.

What about the influence of other boats in the equation? In the event there is another boat that has right of way, the Case Book has the following:

CASE 114

When a boat is entitled to room, the space she is entitled to includes space for her to keep clear of or give room to other boats when required to do so by the rules.

As you can see, there is no definite answer to the problem, but hopefully a better understanding of the rules and definitions is helpful.