Tuesday, 12 May 2009

Mark-Room – Revisited

A guest post by Mike Butterfield

I have been reflecting on the position of the boat giving mark room as has been discussed. A lot of friends have shared their thoughts with me and I am revisiting the position.
The simple one first!

On leeward marks.
Generally RRS 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.
When does it end?
Clearly the right to mark room has ended when both have left the zone but in reality it ends when the boat entitled to mark room has been able to sail her proper course at the mark. See Definition of mark room.
If this is when it applies, are the relationships between the boats changeable?
Well no not really once the relationship is established it remains, 18.2(c) even if later an overlap is broken or a new overlap begins.
The exception is when the boat entitled to mark room leaves the zone or if either boat passes head to wind.
In this circumstance we rely on 18.2(a) unless the circumstances for 18.2(b) become applicable again. Here basically an inside overlapped boat is entitled to mark room.

What is mark room?

MB markroom REV
Well it is a two sided advantage.

Initially Room to sail to the mark. I look on this as giving the boat a corridor of opportunity. If it stays in that corridor (even if give way) it is protected. The protection is in 18.5, this is protection from breaking a rule of section A.

If she strays out of the corridor and the Right of Way boat has to take avoiding action then she has taken too much room and is subject to a penalty as the exoneration is not available. Just as before I believe if the right of way boat freely gives additional room and that is taken by the boat entitled to mark room she may not be in breach, this was the same under the old rules.
When at the Mark there is the right to sail a proper course while at the mark. There is extended exoneration here as it covers not only part A rules but also 15 and 16.
This allows for a sudden course change at the mark to sail the proper course which may be a luff at a leeward mark or a bear away at a windward mark.

Overriding all this, is the obligation of the boats under rule 14 to avoid contact, there can be no exoneration here. The rule itself though assists the boats in that a boat that is right of way or entitled to room or mark room need not act to avoid contact until it is clear that the other boat is not keeping clear or giving mark room, and shall not be panelized unless the contact causes damage or injury.
There will be other scenarios but this gives the basic idea.

Time factor?

I still think there is a time factor in the concept of Room, so if a boat entitled to mark room goes too slowly and a right of way boat has to alter course, she is at risk of losing her exoneration. You have mark room but I believe you have to use it or lose it! On this point we will see.



  1. Hallo Mike
    In my opinion mark room consist of a corridor, which is separated in two parts. One is the corridor "to the mark" like Mikes picture. The second part is also a corridor "at the mark". This second corridor begins, when the first corridor ends and contains the space a boat needs to sail her proper course at the mark. This corridor ends if one of the following conditions comes true.
    a) if no more course change is necessary for the proper course.
    b) if the course change passes head to wind.
    c) if the corridor leaves the zone.
    The time-factor "while manoeuvring promptly" in the definition of room is necessariy to define the space of this corridor, but is not a order to the boat not to slow down.
    Uli F.

  2. I partly disagree with the statement
    "If this is when it applies, are the relationships between the boats changeable?
    Well no not really once the relationship is established it remains, 18.2(c) even if later an overlap is broken or a new overlap begins."
    There is a requirement for a boat to act promptly to take mark room. There will be cases where boat is clear astern at the zone and therefore keep clear, becomes an overlapped inside RoW boat because the boat entitled to room has either slowed down or gone outside the 'corridor'. In this case the boat required to give room has fulfilled her requirements and the new keep clear boat has to keep clear. While she is still technically entitled to mark room she has been given it and chosen not to take it.
    It would be unfair to penalise a boat who has fulfilled her obligations and not penalise a boat who has not promptly taken the mark room that was given.

  3. Whilst the idea that mark room consists of two "corridors" is useful to visualise the geometrical extent of mark room, it is important to realise that there is no separation between the two. Mark-room includes both corridors from the moment that mark room has to be given until it is no longer required.

    This is especially important when considering situations when two boats are approaching a mark on a beat, overlapped (with the inside boat to windward), but both have to tack to round the mark. An inside overlapped windward (IW) boat is entitled to mark room from the moment one boat enters the zone. At this moment, and thereafter (until rule 18 switches off)IW is entitled to room to sail to the mark, and room to sail her proper course at the mark, including room to tack. As long as she is entitled to mark-room she is entitled to the totality of that mark room.

    If IW passes head to wind she loses her entitlement to mark room (18.2c and 18.1a). However the outside boat cannot anticipate that IW will lose her entitlment. Until the moment that IW passes head to wind outside boat must give room to tack. At the moment before IW passes head to wind she is still entitled to room to tack. If, at that moment IW does not have room to tack (even though a split second later she may lose her entitlement) then outside boat has infringed 18.2b.


  4. Team-Race-Call J3 shows, that a boat entitled to mark room and slows down does not lose the entitlement to mark room. In Team Racing is a normal tool to use the right for mark-room if clear ahead at the zone to slow down the subsequent boats of the other team.
    Uli F.

  5. To Uli F
    18.5(a) says that a boat is only entitled to exoneration if she breaks a rule of section A 'as a result the other boat failing to give mark-room'.

    Call J3 hinges on why boat X slowed.
    If it was deliberate, by letting sails go or luffing then I would argue that J3 is an incorrect interpretation as Boat A has given mark room. Boat X chose to slow and therefore did not to take the room given, promptly so she should not be entitled to exoneration. Why should boat A be penalised ? She has given mark room if X had acted promptly (by not deliberately slowing).
    However if it was a reult of changes in wind or current etc then the call is correct as X is doing her best to sail to the mark and A has to continue to give room.

  6. Rule 18.2(c) states: "she must continue to give mark room, even.." This means that the requirement to give mark room continues during the boat entitled to mark room is sailing to the mark and is rounding at the mark. The requirement does not end, when the boat entitled to mark room is slowing down. We shall proof our objective feeling of fairnes only by using the words of the rules.


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