I do not think 18.2b is off, the boat can head back to the mark and is entitled to mark-room.
With respect to starboard, she should give mark-room, but the port boat will not be exonerated if she fails to keep clear, as she is not sailing in the mark-room to which she is entitled. She has taken too much room

I think 18 does apply and that yellow does owe blue and green mark room.  However, neither blue nor green are sailing in that mark room, as it only entitles them to sail to the mark, not sail anywhere they like... which in this case looks to be the other mark.

So by 18 yellow owes them mark-room, which I think she is giving.   The rule 10 still applies and both blue and green must keep clear of yellow.    Perhaps 19 also applies, but I don't think so be cause 18 applies and the obstruction is another boat overlapped with each of them (overlap marginal yellow to green).   But even if 19 applied it doesn't change much, as green is not keeping clear of yellow herself... the rules talks about choosing to pass either side of an obstruction... it doesn't say anything about choosing to be t-boned by the obstruction :)

This is a gate mark, yes? So although all 3 boats are in the zone of the right hand mark (looking downwind) it appears that Blue and Green intend to leave the right hand zone and round the left hand mark. 

"19.1 
Rule 19 applies between two boats at an obstruction except
...
(b) when rule 18 applies between the boats and the obstruction is another boat overlapped with each of them."

Agree with Michael.

Interesting. I think green was required to give mark room to blue. At posn 1, it looks to me like blue is clear ahead.  Green is travelling faster than blue, so blue would have been clear ahead when she hit the zone.  She likely was clear ahead before that and it is unlikely or not clear green established an overlap in time.

Green has not given mark room to blue, as she was required to do.  

At position 2, yellow has given mark room to blue and green but they are not sailing within that room so yellow is not constrained by 18.2. Yellow is an obstruction to blue and green.  Unless blue can gybe and clear green’s counter, her move is to luff and take yellow’s counter.  If she does that, she must give room for green to do the same. At 2, she has not done that.  I do not think she would be exonerated for that failure on account of her not being given mark room by green.

Hmmm... seems like some assumptions are being made to arrive at answers.  Need to know where the next mark is to understand what the boats are trying to do here and determine "proper course;" 18.1(b) might mean 18 doesn't apply and the gate could be a red herring at position 2. Alternately, it "looks like" this is a leeward gate based on how the two boats are sailing, in which case rule 18 never applied to Blue and Green (see definition of "Mark Room"; proper course is not to sail as close to mark on left of screen as possible).

Opinion: even if Yellow has right of way, it would appear collision is imminent between Green and Yellow (and Blue will get sucked into it as well) and Yellow had an opportunity to avoid collision, so rule 14 could also come into play... point being is that if this came to a protest hearing, I would also want to know what communication may have occurred between boats and what actions were taken, even though not strictly required.

I think in all scenarios, Green has a big problem.  If she was overlapped with Blue, she should have gybed around the first mark at a reasonable distance to it, or luffed up to avoid Yellow,  She could also sail on the the other mark (taking Blue with her) if that was her chosen tactic.   If she did not have an overlap on Blue, she should have slowed and gone behind blue and gybed around the first mark (assuming Blue did) within the mark room she is entitled to, or sailed on to the other mark, keeping clear of Yellow.

If Green has no overlap on Blue when Blue reaches the first Zone, and she wants the other mark, she should have gone behind Blue, and then Yellow.

Lots of "should haves" for Green.  she has made a mess. 

If Green had an overlap on Blue, she is clearly about to break Rule 10. (and likely 14!)
If she did not have an overlap, and Blue wants the mark on the left (of our screen) she broke rule 18.2(b), and is about to break Rule 10.

Blue must also stay clear of both Green and Yellow.  At P2, she appears ready to break Rule 10 as well.

Please comment if you see any flaws in my logic.  Trying to learn, and this forum has been great!

If green had an overlap, and is entitled to mark room from blue, she is not required to gybe at the mark, 18.4 does not apply at a gate mark.  

Charles.  True.  That's why I have the "or luffed up to avoid Yellow" (should have said to stay clear of yellow) option there.  

I think Green and Blue are required to keep clear of Yellow so Yellow is an obstruction to them, but as long as 18 is on between them Green is not required to give room for Blue to pass on the same side (if, for example,  Green is able to cross ahead of Yellow). If Green chooses to duck Yellow Blue must keep clear of both. 

The complication I see here is that while Blue and Green are in the zone of a mark they're required to leave on the same side and none of the 18.1 exceptions apply, neither boat intends to round that side of the gate. But both boats retain the option to round the right hand gate so I think 18 is still on between them unless/until they leave the right hand gate zone. 

Cat, does the diagram intend to show Blue clear ahead of Green when Blue reached the zone of the right hand mark, or did Green establish an overlap? 

It looks like Blue and Green intend to round the left hand mark and that Green will be clear ahead when she reaches the zone of that mark. 

Cata--can you clarify whether this is a "regular" gate or a leeward gate as it matters?  The problem statement suggests a leeward gate, the drawing suggests a "regular" gate.

It would be useful to initially establish if GREEN had an inside overlap at the zone.
If yes,
BLUE was obligated to keep clear of GREEN as leeward boat (RRS 11)
BLUE was obligated to give mark room to GREEN for the mark in the zone they are in.(RRS 18.2b)
BLUE and GREEN were obliged to keep clear of YELLOW as the Starboard tack boat (RRS 10)
GREEN has taken more than sufficient mark room for the mark in the zone they're in, therefore under 18.2d, YELLOW is not obligated to give GREEN mark room for that zone, and GREEN is obligated to keep clear of YELLOW (RRS 10)

As this is a gate, the two port tack boats have the option to round the other mark. If they choose to avoid YELLOW and harden up for that mark, then:
As YELLOW is an obstruction to them both, BLUE owes GREEN room to pass astern of YELLOW (19.1b, and 19.2b), and as windward boat, BLUE needs to keep clear of GREEN. (RRS 11)
If BLUE and GREEN make it past YELLOW and head for the other mark, then it looks like BLUE would be in that zone first as the inside boat, and GREEN would owe BLUE mark room at the other mark.

Bottom line: neither BLUE nor GREEN anticipated the options too well as they approached gate and the two zones, and neither took action soon enough to keep clear of YELLOW.

Cata,

As we know, Rule 18.4 does not apply at a gate mark. It does not make any difference where the next mark of the course is. Gate mark(s) have at minimum a required side. 

Given the scenario, the Green boat (PL) is world of hurt here. Part 2 rules apply and the Yellow (S) boat is an obstruction to both Green (PL) and Blue (PW). PL has a choice to which side to pass the obstruction. She must act in time to either give room to PW to pass between her and the S boat or sail a course to pass the stern of S, in which case PW must give PL room to do so. See the Cases below.

From the diagram, there is very little chance of PL being able to satisfy 19.2.b, hence breaks it. Additionally, rule 10 will not make her life happy. One question remains: was S able to avoid contact? If not, S maybe on the hook for breaking  rule 14, since she could have avoided contact when it became obvious that PL was not keeping clear.

It may make a difference in what type of a boat we are sailing here. Optimist type dingy will have no problem gibing in front of S without breaking rule 14, but most other types of boats (with Assy), this will most likely result of some fiberglass repairs. 

Cases to check: 

Case 11:

Although the Case 11 is a situation on the windward leg, the rule 19.2.b applies here. Case 125 has a similar motive, but with more than 1 boat needing room at an obstruction.

Case 124:

____________________________________________________________

Another way to look at this could be to take the marks out of the picture and ask: Would anything change for Green?

 

Cheers!

Kim

Tim Hohmann
Cat, does the diagram intend to show Blue clear ahead of Green when Blue reached the zone..

NO Tim, Green and Blue are overlaped when they reached the zone.


Jason Fox
Cata--can you clarify whether this is a "regular" gate or a leeward gate

Jason, it's a leeward gate......a 29er regatta club

Mike B,

Can you explain a little more why you think rule 18.2(b) does not cease to apply in accordance with rule 18.2(d).

EDIT:  Corrections below, after seeing Catalan's and Tim H's posts below.

Both B and Y have given never less than 2 BL of space between G and the mark:  isn't that room given?

EDIT:  No, G remains entitled to room to gybe, sail close to the mark then harden on on starboard tack to leave the mark.

My mistake was to presume that B, once way outside the mark on port gybe, never would be able to interfere with G gybing and rounding:  that may or may not be true.

I agree, that under the current rules, rule 18 does not go off in its entirety, and G, overlapped inside remains entitled to room under rule 18.2(a).

EDIT:  So 18.2(b) remains on

So, rule 18 applies, and the switch off in rule 19.1(b) applies and rule 19 does not apply between B and G with respect to G.

Under the 2021 rules, the whole of rule 18 will go off when B and Y have given G mark-room and Y has given B mark-room, so the rule 19.1(b) switch off will not operate and rule 19 will apply between B and G with respect to Y.

EDIT:  No, 18 does not go off in this case.

This is a ZOOM VIEW of the same scenario

I´d like to think about this.
At position N°1
Green is entitled to mark-room for 18.2b

At position N°2, Green have recieved that mark-room yet ?

THANKS !!!!

I would say no. Green could still decide to gybe and round the right hand mark, and if she did her proper course would be to sail close to it. I believe Green's entitlement from Blue persists until she either rounds the right hand mark or leaves the zone on her way to the left hand mark.

Thanks you all so much !!!

I wonder, how much Mark Room, must Blue give to Green ?
And i think that the answer is in the DEFINITION

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 the mark as necessary to sail the course.

So i think that Green has recieved the mark room it was entitled with the left mark when
"her proper course is to SAIL CLOSE to it"

So interesting case !!!
I must keep studying !!!!
Thanks friends !!!

From the diagram it looks like Green will be clear ahead when she reaches the zone for the left hand gate mark so Green will be entitled to mark room from Blue. If Blue is able to maintain an inside overlap Green will have leeward ROW but Blue will be inside and entitled to mark room

Cata,
Has the scenario changed to a single leeward rounding mark? If yes, the last sentence in rule 18.4 is no longer part of the discussion and rule 19 is out of the picture as well.
Case 118 gives us additional information about Mark Room in the definition.
Case 118:
In the definition Mark-Room, the phrase “room to sail to the mark” means space to sail promptly in a seamanlike way to a position close to, and on the required side of, the mark.

The answer to your question: At # 2 Green have recieved that mark-room yet ?
In your scenario, it appears that blue did not impede at any time, green's course to sail to the mark.
The question that may be asked is: Did green satisfy the first sentence of rule 18.4? That would be for PC to decide.

Kim

Kim, Is the same scenario 

Why are you exempting Yellow from her Mark Room obligations to Blue and Green?
She is overlapped with both when each enters the Zone.

With respect to the right hand mark I think Blue & Green are outside the mark room they're entitled to from Yellow.

Green is outside the mark room Blue owes her, but Green has ROW. 

Philip Hubbell. See RRS 18.2d. Both the port tack boats have sailed beyond the room they are entitled for the mark in the zone that they are in, so 18.2b turns off. Now the port tack boats are subject to RRS 10, and YELLOW is the ROW boat.

Tim O,

I think you are confusing the switch-off of rule 21 exoneration by a boat not sailing within the mark-room to which she is entitled, with the switch-off of rule 18 .2(b) by rule 18.2(d), when mark-room has been given.

Sailing outside your mark-room doesn't, of itself switch off an entitlement to mark-room.

The mark-room that G is entitled to is room to sail back towards the mark and round it.

While one might think that B would not be able to interfere with G gybing and doing that, conceivably, G might go downspeed, muff her gybe, or otherwise give B the opportunity to interfere with her rounding.

G has not yet been given that room so she remains entitled to rule 18.2(b) mark-room.

And once G gybes back towards the mark, she will again be sailing within the mark-room to which she is entitled and will be entitled to rule 21 exoneration.

John Allen. Disagree. RRS21 is on when GREEN is sailing WITHIN the mark room she is entitled to. Green's mark room in that zone is to sail close to the mark. Green is well beyond that, including room to gybe, and assuming that's a 3 boat length zone, she's about 2 boat lengths away from the mark, and still sailing away from it.Therefore green is not entitled to exoneration for breaking rules in Part A, 15, 16, or 31. Nothing is compelling her to break any rule. 18.2D applies.
There was an identical situation between two RC boats, (IOM's) port versus starboard going for the same gate mark.. Don Martin also found that the inside port boat that had been given mark room including room to gybe, sailed beyond that room and made contact with starboard. Decision: port penalized RRS 10, and 18.2d turned off 18.2b

Have you got a case that I could refer to?

Tim O,

I agree that while ever G is on port gybe, she is outside the mark-room to which she is entitle and will not be exonerated by rule 21 if she breaks a rule of Part A or rules 15 or 16.

That does not mean that she rule 18.2(b) has ceased to apply.

To round the mark on the side required from Position 2, G's proper course is to sail close to the mark, so to sail that course she needs to gybe.  Once she gybes towards the mark, she is sailing within the mark-room to which she is entitled, being room to sail to the mark, and once there, room to round it as necessary to sail the course.

If you have seen a similar example where the port gybe boat was penalised for breaking rule 10, that says nothing about what happens to a boat that is once again sailing towards the mark.

John A. If YELLOW wasn't there at all, BLUE owes mark room to GREEN up to the point that sufficient room has been given to sail her proper course to sail close to that nearest mark. Recognizing that gybe angles are tighter on sprit boats, without current set information, it still looks like GREEN has sailed beyond a reasonable amount of room and beyond a reasonable gybe angle. In BLUE's position, they almost have enough room to make a risky decision to gybe inside. The risk is that if GREEN decided to pull off a quick gybe, BLUE gets stuck as windward keep clear boat and her only defence being whether GREEN left the opening when breaking 18.2d. So... putting YELLOW back in the frame... and still under a finding that GREEN took more room than entitled,.. GREEN looks like it will get T-BONED by YELLOW unless YELLOW takes immediate avoiding  action, with GREEN guilty of breaking RRS 10. With no other weather, and current information etc.. it looks like BLUE's best option is to head for the other gate, probably with inside rights and mark room on GREEN, if somehow GREEN can avoid YELLOW and keep heading to the other mark.

John A..

EDIT: re your last question, the IOM situation was exactly this. The IOM zone under RRS Appendix E is 4 BL.  The course was DDW, as IOM's sail best DDW, wing and wing.. PORT INSIDE boat was given 2 BL  of room which was easily sufficient for PORT to gybe at that gate mark. STARBOARD OUTSIDE prepared to head up to the mark and hailed  "Starboard" once PORT had sailed well beyond the point at which they should have gybed and headed for the mark . There was minor contact. PORT penalized. Incidentally, as PORT had sailed too far, and held starboard away from their course to the mark, other boats sailed into the gap left by port's poor rounding. Starboard lost a few places. PORT's  subsequent penalty turn hardly made up for Starboard's loss of places., but that's boat racing !! 

To John Allan A response to your question. I ask you to look up TR Call J7 and MR Call E1 which have comments on an interpretation that are similar.
18.2(B) does not cease to apply because the definition os "Mark room" still applies. The boat can by reversing course have a then proper course which would pass close to the mark, and she still needs to round it. Nothing in the rule says from where you have to approach the mark and you can do so and retain your mark room as long as you do not leave the zone or tack.
Clearly whilst sailing outside the mark room you are entitled to the usual rules apply with no possibility of exoneration.
The 2l is room given but you still have to give "Mark room" and when the boat heads to the mark all the rights of mark room apply and the extra distance to get to that point is ignorred.
I agree about RRS 19.
Your last paragraph about thee new rules is possibly premature, Before the turn back to the mark 18 applies and 19 is off, starboard has to give mark room. This follows as 18 will even under the new rules switch off only when the boat returns and passes the mark. 
Hope that helps.  Mike

Mike B,

Thanks for your patient explanation.

As you can see from the edits I made after seeing Catalan and Tim H's posts, I came around to your way of thinking, so now it's Tim O that needs convincing.

I note that MR Call E1 isn't a good reference because rule C2.9 omits rule 18.2(d) for MR.

I think I can follow Tim O's logic:  in the OP case, somewhere before Position 2, if G had gybed, there was plenty of room for her to sail to and around the mark, if only she had taken it.

TR Call J4 would seem to cover my point where the ruling says at position 3  the inside PORT boat is no longer sailing to the mark.
I don't think MR E1 describes the same situation as closely as TR J4

I guess I'd ask a question, which may only be relevant at a gate mark. Does the "corridor" of mark room a boat is entitled to begin from where she enters the zone (which assumes she sails directly to the mark) or from her current position? If, without leaving the right hand zone,  Green decides at position 2 that she wants to gybe and round the right hand gate, is she within her mark room entitlement from the time she gybes and begins sailing to the mark? If Green gybed into a windward overlap with Yellow, could Yellow take Green up or close the door? 

I'd still maintain that 18.2 stays on and Green's entitlement to mark room at the right hand gate persists until she either rounds the right hand mark or leaves the zone, but my question is exactly where is that mark room located? 

Tim H,

My opinion, and I think MIke B's is that the 'corridor' goes from where she actually is, to the mark.

Others think that it's from where she entered the zone to the mark.

Case 75 says That space was a direct corridor from S1 [where the boat entered the zone] to a position close to and alongside the mark on the required side.

Mike B, what do you think of this interpretation in Case 75?

Note that this is all about rule 21 NOT the application of rule 18.2(d).

Tim O,

TR Call J4 is about the application of rule 21 and the meaning of mark-room, not about whether rule 18.2(b) applies or not..

I still think you are confusing a boat sailing outside the mark-room to which she is entitled with a boat disentitled to mark room by rule 18.2(d).

They are not the same thing and the conditions in rule 18.2(d) for rule 18.2(b) ceasing to apply do NOT include sailing outside the mark-room to which she is entitled. 

We do not know the wind and sea state, nor the boats' speed, nor the sailors' abilities in the conditions.
Green might reasonably claim that in the given conditions she anticipates a violent round-up following her gybe.
Thus she is taking the room she might take in the absence of the other boats.
(And she might thus claim entitlement to delay her gybe vis-à-vis Blue and 18.4, even if it had it not been a gate.)
Nevertheless, Yellow, with ROW, has obligations only to give Green and Blue mark room to sail TO the mark. 
This means Green and Blue bearing away to a less than optimum run and gybe well before position 2.

J Allen. I know the TR Call J4 is not about the applicability of 18.2b.  I didm't suggest it was. I referred to it because it fits the situation between GREEN and YELLOW. J4 found that because Port Inside had altered course away from the mark at Y3, she was" not sailing TO the mark, nor rounding it" and found it had not sailed within the ROOM GIVEN. Consequently, RRS 21 turned on. The point of J4 that is useful here, is that if Y3 was no longer sailing within the room given, the same conclusion can be drawn here. GREEN had been GIVEN mark room, i.e. room to sail TO the mark, and sufficient room to ROUND it with no other boat interfering with that. However GREEN is sailing a course almost 180 degrees and 2 boat lengths away from the mark. In my opinion, RRS 21 turns on in the same way that it does in J4.

By entering the zone with an inside overlap, "at that moment" (RRS18.2b) GREEN was only entitled to room to sail TO the mark and round CLOSE to it.  Not entitled to any other room beyond that, no fiddling about, no driving other boats away from a mark etc... . Sailing 2 BL's away from the mark in the opposite direction means GREEN sailed outside the conditions of RRS 18.2. b, and not eligible for exoneration for that (due to 21), nor exoneration for the probable RRS 10 situation with YELLOW.

Now in the context of the above and 18.2d: in order for GREEN to have broken 18.2b, and 21, she must have been GIVEN mark room already. "When a boat entitled to mark room has been GIVEN that room, 18.2b and c "cease to apply"

To me, if a boat is granted certain privileges, then obviously squanders that privilege, from the moment that they break the conditions of the grant, they lose the privilege. I see 18.2d in that light as a double edged sword. While they sail within the grant of 18.2b, 18.2d gives them the protection of 18.2b right up to the point that they have been GIVEN room to round the mark (as 18.2d says). Once GIVEN, the other edge of the sword applies, the grant is revoked.

Phillip H, we can only rule on what we see here. If there were a strong adverse current, I can see why GREEN might have a proper course pre-gybe, that has her sailing away to gain room to gybe and get swept back to round the mark without hitting it. We don't know that and can't speculate.
Similarly we can't speculate on the the sea state, nor the skill of the crew to sail deep TO the mark, from the moment they acquired mark room, do a gybe and a Mexican drop with the asymm right at or CLOSE TO at the mark as required of them (and as any reasonably skilled crew of a sprit boat flying asymms)

I feel like J4 is a poor precedent for this scenario J4 considers a single leeward mark so a boat's proper course is to round that mark. With a gate a boat might decide at any point that her proper course is to round either mark. So Green is sailing her proper course if she decides to round the left hand mark (although not yet in the zone for that Mark) but could decide that her proper course is to round the right hand mark instead. 

Tim H, true it's a gate. GREEN can only claim mark room at the nearest mark in the zone she's in. If BLUE and YELLOW have given that room  then the scenario in J4 applies. In any event, agreed GREEN could change its mind and head for the other mark. GREEN still has to keep clear of starboard YELLOW while YELLOW has given GREEN room in that zone. That's the relevance of J4 in this situation. Bottom line, it looks like GREEN left the gybe too late, is now too far ahead to head up and ask for room from BLUE to pass YELLOW's stern, and has left it very late to gybe away from YELLOW. A fustercluck of indecision when GREEN was so close with mark room given, if they simply drove deeper, earlier and gybed.

No, you always retain the privilege if you comply with the terms that granted it.
There is having mark-room and separately there is the corridor, as we call it where you have mark room and are exonerated for breaking certain rules.
So here when the boat enters the zone 18 applies and there is a corridor to the mark from the point of entry, why .because the proper course of the boat is to sail to the mark.
Here the boat sails outside of the corridor, we all agree that, over on boat she is right of way leeward (and subject to 16.1),  and she is give way port to the starboard tack boat, and here must keep clear.
Assume at the last position she could reverse her heading and head for the mark. Now her proper course is to sail close to the mark  etc so there is a new corridor to the mark and in the thin new corridor, she has mark room and again is entitled to the exoneration for the breach of the other rules specified.
So having strayed from her corridor when she returns she gets a new corridor.
I do not see her as having had mark room untill she has lest the mark on the required side.
A caveat, I do not think she can always have a new corridor back to the mark. If she had sailed further past the mark (but in the zone) and was below it her proper course may be below the mark and not to head for it to say shut a boat out. Here her corridor would follow the course to the next mark which could be some distance below the mark. This is because she only gets a corridor to the mark when her proper course is to sail to it. In this circumstance, the proper course is below this.
I hope this sets out my thoughts in a manner you understand.

Michael, I have always understood your interpretation and how others have expressed similar views. I just don't agree with it, due to the varied contexts that the words Mark Room GIVEN have bern interpreted, or the meaning implied across different rules. The point of my line of reasoning is to point out the different ways that GIVEN can become ambiguous. Some of the reasoning i see you and others presenting presumes that GIVEN is synonymous with TAKEN. e.g your words above say you consider mark room as given, only once the boat has TAKEN the mark room and left the mark on the required side. If i give you all the space you need to round the mark, then from my perspective, the obligated boat, I have met that obligation and have GIVEN it. If that boat squanders it, fiddles about, doesn't head TO the mark, takes me out having met my obligation, that doesn't change the fact that I GAVE totally adequate room to round the mark. That's where we differ, This is the basis of why I think it's reasonable to declare that the provisions of 18.2d have been met.

The definition of mark room and literal interpretation of the words and the intention, has been a bit muddied in my opinion with the ambiguity of saying that room is TO the mark, when the proper course is to sail CLOSE to it. A problem arises for me with the use of words "WHEN the proper course is to sail close to it'. The ramifications of your use of WHEN, is that the boat GIVEN the necessary room can sail away, stay in the zone, force others away from rounding and then decide to use the now excessive room, to apply the privilege. That sounds beyond doing it for a seamanlike rounding, and borders on causing chaos for others down the line.

That's equivalent to taking too much room for which there are numerous cases and rulings against that abuse of the privilege. There have been decisions that imply that a boat's proper course in the zone for MARK ROOM is to sail TO and CLOSE to the mark, not 180 degrees away from it and 2 BL's at that.

I will have to spend a week or so cataloguing the cases relating to too much room, where the ruling has interpreted the proper course for mark room in the zone, is to sail TO and CLOSE.

Who said sailboat racing is like watching  grass grow? LOL.

I have to ask:
In this situation, sailing 49rs, are still talking about Mark Room?

I would like to know what happened in the next second or two.
Oh, if the PC needed to know what the course for green would have been to claim her mark-room, just ask any other 49r ahead or behind. That should take care of the wind, waves, current, etc to establish the room needed to sail to the mark when her proper course is to sail close to it. Presuming we are still considering rounding the Starboard (looking down the course) gate mark.
From the moment Green and Blue entered the zone, the rules gave Green mark-room, unfortunately, she did not take it. Blue had mark-room on Yellow, but given the position, she was not able to claim it. 
Cheers,
Kim

Tim I came from the same place as you when the concept orMark Room arrived. I found others interpreted it differently so I moved over to the mainstream interpretation so as to follow what would be upheld on appeal or met with the fellow jury consensus.  
I mentioned match and team racing calls above. I did not agree especially with the MR one but saw the interpretation and adjusted my thinking.
Most of the cases for "taking too much room" are when you are the give-way boat, and of course here the give way boat would be disqualified for the port starboard.
If you are the right of way boat you can do what you want, (subject to 16.1) but when you want you can turn back and rely again on your mark room.

Isn't it best not to think in terms of derived/invented concepts like "taking too much room" and instead focus on the direct concepts like giving mark-room. 

Yellow is ROW, but her right to sail her course is limited by her obligation to give mark-room. So from the moment 18 applies what must Y do(have done) to allow B & G to sail to the mark and round the mark?  Bear away? In this case no, as there is/was ample room for B & G to have sailed to the mark etc.  They choose (or at least G choose) not to take that room, but that does not entitled then to even more room. If it did then mark-room would allow a boat to sail any course!

So instead of asking at this if at this instance do B & G now need more room to gybe and sail to the mark, just ask did Y give room when she was obligated to do so. She did. Did she do anything to prevent B & G sailing to the mark? She did not. So given that she has met her obligation under 18, she is still ROW by rule 10 and that should play out as if there was no mark.

In short, ask was there room given, not how much room can be taken.