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?

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.
.