The preamble to Section A of the RRS says
A boat has right of way over another boat when the other boat is required to keep clear of her. However, some rules in Sections B, C and D limit the actions of a right-of-way boat. 
 
So when R 18 applies and grants Mark Room then the ROW boat must provide that room.

Should it go to a protest - Yes - protests are a great way for the competitors to improve their understanding of the rules - and in this scenario, if STBD pushed Port off her proper course in the zone, but subsequently left room and let her in to round the mark, STBD still broke R 18.2(b)

John

Yes Rule 10 applies, giving A Right of Way.  But Rule 18 also applies giving B Mark Room.  What this means is that Boat B must comply with the terms of Rule 18 and Boat A must give B Mark Room to round the Mark.  In practice, this means that Boat B must not sail wide, to make a "tactical Rounding".

Yes, and yes, A is not correct (in denying "mark room").

Whether it should go to a protest depends on the details of 5 and 6.  "denied" suggest that B should protest A if A didn't provide "mark room",  but no collision and that "both boats rounded" might suggest that "mark room" was provided (and that no foul occurred).   So, I think "it depends" might be the answer and it would depend on what actually happened in 5) and 6).

Rule 10 applies here. Rule 18 also applies. The outside, starboard boat needs to give mark room to inside port. 

Mark Room 
Room for a boat to leave a mark on the required side. Also,
(a) room to sail to the mark when her proper course is to sail close to it, and
(b) room to round or pass the mark as necessary to sail the course without touching the mark
However, mark-room for a boat does not include room to tack unless she is overlapped inside and to windward of the boat required to give mark-room and she would be fetching the mark after the tack. 

The parties in this situation are likely conflating the concept of right-of-way with the concept of mark room.

Right of way rules are port/starboard, windward/leeward, ahead/astern, and while tacking. 
Mark Room is a limitation on a right-of-way boat, it does not change who has right-of-way. 
Put another way, right-of-way is only part of a situation and while you can often have right-of-way, Rules 14-20 limit or demand action of a right-of-way boat in certain scenarios. 

John B re: “if STBD pushed Port off her proper course in the zone, but subsequently left room and let her in to round the mark, STBD still broke R 18.2(b)”

Be careful here.  Mark-room does not include room to sail your proper course.  See def: Mark-Room for what it actually does include. 

We have no contact between boats or the mark .. so whether or not Boat A broke a rule might depend upon the avoiding actions of Boat B and the details of how they eventually rounded the mark. 

If Boat B still rounded inside Boat A, then it might be found that A gave MR and Boat B kept clear. 

If Boat B had to take A’s stern when avoiding Boat A, then it might likely be found that Boat A did not give MR. 

I think the issue I am having is that I cannot see a place in the RRS (maybe I'm not looking hard enough) where it gives priority to rule 18 over rule 10.
I believe that rule 10 applies, and I also believe that rule 18 applies, but what is the mechanism over giving priority to one or the other.

To clarify the situation:
Boat A (starboard) is about to make a tight rounding and boat B, (port) is claiming inside overlap.  During the mark rounding boat A will have to gybe onto port to round up.
But the assumption is that boat A is trying to shut boat B out of the mark rounding by bearing off by the lee and then gybing at the last possible moment, thereby forcing boat B to avoid and go behind.  The issue of entering the zone and activating Rule 18 is what is confusing to me.

Henry, nothing, in the rules, turns off the 4 right of way rules when rule 18 applies at a mark and nothing in the rules turns off the right to room in rule 18 when the give room boat has right of way.  So, both apply at the same time.  
The solution is to apply both rules separately but then go on to apply the the exoneration rules.  If I add to or clarify the facts to say that the starboard boat pushed the inside port tack boat off its course to the mark (adding facts, agreeing with Angelo) and then headed up to avoid a collision with the port tack boat, then the port tack boat did not keep clear of the starboard tack boat and so breaks rule 10.  However, since the port tack boat is sailing within the room to which she is entitled, she is exonerated by rule 43.1(b).  Since mark room includes room to sail to the mark, the starboard tack boat did not allow this room and breaks rule 18.2(b). When we look through the exoneration rules, there is nothing to save the right of way boat from such a rule breach and so they will be disqualified.

 

 

The exoneration of a give way boat sailing within the room to which she is entitled is confirmed in US Appeal 120 (Walloping Swede and Wonder), a port starboard crossing case.  The strange thing in that appeal is that the starboard boat is not dsq’d under rule 16.1 for failing to give the port tack boat room to keep clear even though it failed to do exactly that.  It appears that the committee is rewriting rule 16.1 for port tack crossings from “shall give room to keep clear”, to “shall give room to avoid a collision”.  Maybe a rule change is needed so we don’t have to rely too much on cases and appeals.

 

Henry, it helps to resolve your angst about potential 'conflict' between rules 10 and 18 if in this circumstance you view 18 in the same light as rules 15 or 16.  S is right-of-way boat, but has an obligation to provide P, who is inside, with mark room.  If P takes more room than warranted by the definition she breaks both 10 and 18.  But I am repeating someone else I think.  Warren

Warren re: “If P takes more room than warranted by the definition she breaks both 10 and 18.”

Since P doesn’t have to gybe at the mark in this scenario, can you elaborate on how P breaks 18?  Seems to me we only have an unexonerated 10 breach. 

Warren, the source of my angst can be described by reversing your statement:
P is entitled to mark room but is on port, so must give way to S.
There is an explicit exception to Rule 18 at a windward mark involving port-starboard situations in the Zone, but none at a leeward mark.

Angelo, OK, I shot from the hip rather than opening the book.  If port takes more room than defined by the definition mark room, and P fails to keep clear of S by doing so, then P breaks 10.  There is no apparent basis for P breaking 18 at this instant. (blush)  Maybe I should just hang about the sidelines.  :-)

To Henry, pragmatically, turning off rule 18 'between boats on opposite tacks on a beat to windward' is a rational approach if some modicum of collision avoidance exists in the RRS.  Applying the same principle to a leeward mark would be an invitation to chaos as it would encourage some pretty aggressive gybing. There may be a better reason, but I have always been happy with 'just because.'  I think it makes racing better, assuming that the sailors recognise the distinction.

Warren … it’s an awkward setup with inside boat being on port and outside on STB in a port rounding.   I had a couple back and forths with Henry on the details of the scenario before posting to make sure it’s what he was after.  

Henry .. look at it this way….

Put boat A on port tack … so now both boats are on port … with B on the inside and A on the outside.  You might look at that scenario and say … ‘oh .. of course … B needs to keep clear of A and A needs to give MR. ‘

Putting A on port doesn’t really change much though … except the rule by which B has to keep clear of A (rule 11 vs rule 10).  Otherwise it’s the same … 

Maybe writing the conclusions that a protest committee could reach (assuming it found A did not give mark-room) will demonstrate the ROW - Room - Exoneration pingpong.

So the only boat that broke a rule and is not exonerated is A.

Decision:  Penalise A.

Henry— I think John’s post points to the end of your angst. Rule 43.1 b (and c) explicitly states which rule wins:

43.1.
a) When as a consequence of breaking a rule a boat has compelled another boat to break a rule, the other boat is exonerated for her breach.
b) When a boat is sailing within the room or mark-room to which she is entitled and, as a consequence of an incident with a boat required to give her that room or mark-room, she breaks a rule of Section A of Part 2, rule 15, 16, or 31, she is exonerated for her breach.
c) A right-of-way boat, or one sailing within the room or mark-room to which she is entitled, is exonerated for breaking rule 14 if the contact does not cause damage or injury.

Maybe what's bugging Henry is why RRS 18.1 turns RRS 18 off between boats on opposite tacks at a windward mark, but not at a leeward mark.

One explanation is, as Warren has said is "because it does".

Maybe this rationale will help.

Boats approaching a leeward mark running downwind, even if on opposite tacks, will be travelling more or less in the same direction, will clearly have the appearance of Clear Ahead, Clear Astern and Overlapped that we would intuitively expect, and will be changing course in the same direction around the mark, so a rule allowing the inside boat mark-room, depending on Clear Ahead or Overlap at the zone will work and be useful.

Boats on opposite tacks approaching a windward mark, OTOH, are travelling at 90 degrees to one anothe, so one will need to make a radical change in course, including a tack and an extended  RRS 13 obligation  to keep clear in order to get around the mark.  A rule for Mark-room between these boats on opposite tacks is going to be difficult to devise and implement.

What ultimately bothers me with this scenario is that if two rules apply at the same time causing a conflict between the two rules, it's messy to rely on an exoneration rule to decide which rule to adhere to in that situation on the water when decisions need to be made quickly.  It would be much neater if the rules were a bit more explicit in this case.  
Then perhaps protest room situations could be avoided.
I appreciate everyone's input into this matter.

Especially for Angelo and John Ball.

Considering John Ball's first comment and Angelo's "careful here" - I've shown the above drawing of the incident (or what might have been - using RC 4 boat lengths). At P3, Red luffs slightly to her windward, towards the Mark, thus denying Blue the opportunity to sail direct to the Mark (her "Proper Course"?) but then bears away to give adequate Mark Room at the Mark. So has Red denied Blue "Mark Room" at P3? I.e. is Blue entitled to sail direct to the Mark, or only Room to actually sail round it? I fully understand the R43 implications, but my point is, could Red enforce her ROW to take Blue to the right so long as she ultimately allows Mark Room at the Mark.  It seems that Angelo and John B disagree, and as I read the rule, I'm not sure. Are there Calls/Cases to clarify?

Not the situation in question.  The mark is to be left to port, and the diagram shows boats leaving the mark to starboard.

Stewart, Henry’s setup is a bit unusual .. and tripped me up a couple times too :-). 

Henry, the rules about right of way and the rules about room are designed to be complementary, not contradictory. 

In your original scenario the Starboard boat has ROW and port must keep clear, but P’s entitlement to mark-room limits the course S can sail. S can sail any course she pleases as long as she doesn’t deny mark-room to P. P is protected as long as she’s sailing in the mark-room she’s entitled to, but if she sails outside that “corridor” she has to keep clear of S.

Stewart, I think US Appeal 20 answers your questions. As Tim alluded, it defines a corridor of room established when the first boat reaches the circle and that corridor is straight from where mark room started to close to the side of the mark.  I think the implication is that if the ROW boat tries to push the boat with mark room out of the corridor, they break 18.2(b).

 

The other point to be clear on is that “mark room” is not room at the mark but room to do the 3 actions and sometimes room to tack as listed in the mark room definition.  So again, mark room can be infringed before reaching the mark.

 

I think John misspoke when he used the term “proper course” in his answer as the appeal is clear that mark room is a straight line going close to the side of the mark and does not give protection for a proper course (tactical) wide in to the mark, close out high lane, rounding.

Keep in mind that 14, 15, 16 & 17 similarly place limitations on what a ROW boat may do. 

To clarify my comments about proper course, here is how I imagined the scenario from the original post and description.

At  P1, the boats reach the zone of a downwind mark to be rounded to port, with Green outside and on stbd, and Red, overlapped inside on port. At after P1 to P2 Green alters course, causing Red to stay clear, but now Red is sailing towards the wrong side of the mark. At P3, Green provides mark room and Red is able to pass on the correct side of the mark. There was no contact.

My view was that in the scenario, Green breaks R18.2(b) after P1 by causing Red to sail off her 'proper course' which was to sail close to the mark.

I agree with Bob's comments about the importance of exoneration and R 43 in the mark room rights of Red.

John

John Ball, I agree with you except for a minor change in wording.

Between positions 1 and 2 when S altered course in the zone, she broke 18.2(b) by not allowing P to sail to the mark when P's proper course was to sail to it. At that moment P could have protested S.

By position 3 it looks like S was acting right and giving mark-room, as long as P could get around without contacting S or the mark.

John Ball

said Created: Today 23:24

Angelo's advice to be careful about applying the term 'proper course' in mark-room situations is to an extent a semantic quibble, but judges are suppossed to be semantic quibblers.

There is no entitlement for a boat to sail her proper course (except in the MR definition of mark-room).

'Proper course' is used in the Definition mark-room to define a particular space.

True, once the mark-room corridor is defined by reference to proper course, a boat sailing within it will usually be sailing her proper courses, but an exception might be an assy boat, whose proper course might still be to remain on her hot powered up course, then gybe back to he mark.

Also on semantics and catch words:

The corridor defined by case 75 and applied in US  Appeal 20 is not the proper course of the inside boat!  Proper course is the course sailed to finish as quickly as possible if the other boats in the rule are not considered.  In these leeward mark rounding cases, the proper course is either the tactical rounding course – head out wide and cut in close to get a high lane on exit – this is justified if other boats are around that might slow you if sailing a lower course or you think there is a port tack lift coming.  The other proper course would be medium wide in and medium wide out with the boat very close to the mark when its course is right angles to the wind i.e. dead down wind from it.  I’d call it an apex rounding as the apex of the turn is closest to the mark. That course goes the minimum distance to leeward and so is the fastest if no other boats are in the area.  (See https://sailzing.com/leeward-mark-rounding-paths/) Neither of these options is the course required by case 75 which is essentially close in which results in wide out.  However, both the proper course possibilities do sail “close to the mark”, one directly down wind of the mark and the other about 45 degrees past that so they satisfy the criteria set to include “room to sail to the mark” in the definition of room to be given in this case.

 

In the definition of mark room, the reference to proper course is just a test to see if “room to sail to the mark” is to be included.  Sailing straight to the side of the mark is not defined to be the proper course and indeed, sailing proper course is not part of the resulting definition of mark room, just sailing to the mark is, as further interpreted by Case 75.

 

So when John says that green breaks rule 18 by forcing blue to sail “off her proper course” this is not correct as red has no right or room entitlement to sail her proper course. Green breaks rule 18 by forcing red to change course when she was in the mark room corridor. Indeed, red’s proper course is to the right of the corridor looking downwind.

John B .. thanks for the diagram. I’d note that the OP-facts do not include “Boat A altered course toward Boat B” .. which is shown in your diagram. 

I like your diagram at 1 .. and Boat A would not provide Boat B MR if she simply held her course at #1 all the way to the mark and rounded.  

This second diagram is truer to the original situation description with the minor change that green did not alter course until just before position 3.

Funny to read this thread today.  I just had this situation in a club ILCA practice session race yesterday and was the outside, starboard boat, and irked by the amount of space the inside port boat was taking with its boom at 90 degrees sticking out towards mine at 90 degrees.  I gave him room but protested him and he did his spins but said he'd check the rules.  He showed me he was right later.  If there is any doubt I think the preamble to section A of Part 2 Right of Way, where rule 10 is, clarifies that rule 18 (in Section C At Marks and Obstructions) limits rule 10:

"A boat has right of way over another boat when the other boat is
required to keep clear of her. However, some rules in Sections B, C
and D limit the actions of a right-of-way boat."

"A boat has right of way over another boat when the other boat is
required to keep clear of her. However, some rules in Sections B, C
and D limit the actions of a right-of-way boat."

This is the problem with the current rule set that I've had all along.  Many places in Sections B, C, and D do describe how they limit the actions of a right of way boat.
The mark-room rule doesn't do it very well at all, which creates issues like Tad experienced on the water, and this case in this thread.  I suspect there are lots of instances on the racecourse that have disadvantaged boats unnecessarily because it is very difficult to interpret rule 18 vis-a-vis rule 10 when you have to make a rules decision in a few seconds while negotiating a mark rounding in traffic.

Rule 10 says that Boat A had the right-of-way at first, but when there was a gap and Boat B called for mark-room, Rule 18's rights and duties came into play tunnel rush.