Q1 After calling you tack the windward boat is responsible.
Q2 She had room to tack and tacked. Then sh became windward boat and should keep clear, this is after the tack so no exoneration.
Q3 se before here no problem.
Q3a room is to tack not to get to a close-hauled course.
Q3b no she must proceed in a seamanlike matter the essence of Room.

Hi Angelo,
is it also worth adding a question about what room to tack means? 
Is it room to start to tack ie to pass htw? 
Or is is room to complete the tack to a close hauled course?
John

Room to tack is to tack, that is pass head to wind.
No right to go down to a close-hauled course.

Tack as a verb is not defined.  Rule 13 gives a clue, 'while tacking' is after passing head to wind until on a close hauled course.  If room to tack is only room to pass head to wind, that is little different to luffing to head to wind, which yellow could do without recourse to rule 20.

Here is a variation. The question is " Did Blue give Yellow room to tack"?

Oxford dictionary
Tack
an act of changing course by turning a boat's head into and through the wind, so as to bring the wind on the opposite side.

Nothing about close-hauled course.

I think these questions illustrate the need for a defined term: "Coming about". I think we discussed this before as well, and this sorta solidifies it.

IMO, room to tack includes room to come all the way through the tack to close-hauled. If it were just room to cross head-to-wind, it wouldn't be much better than the leeward boat just going up to HTW to begin with.

Also, I will repeat my comment that RRS 20 is to make racing more fun and fair, and isn't really about safety, as most of the time, the leeward boat could simply slow down or luff up and accomplish the same safety goal (but would be losing ground to do so).

I totally agree with Niko.

I think “tack” is a nautical term and we should consult sailing texts and sailors before going to a dictionary.  Unfortunately I haven’t found anything quotable from sailing books.  I think the best approach would be to ask a large number of sailing instructors what they mean when they teach their students how to tack.  I’m pretty sure it would be something like “a maneuver that takes a sailboat from close hauled on one tack through head to wind and down to close hauled on the other tack.”

I’d also like to note that “tack” is used in rule 44.2. It defines a one turn penalty as “each turn including one tack and one gybe.”  If the turn had the gybe first then by Michael’s definition, the penalty would be complete upon passing head to wind. I don’t think that’s generally accepted but have seen no authoritative discussion.  I have seen videos of radio sailing windward marks where a port tacker crash’s the starboard tack line-up, breaking rule 10 and then spins into a gybe, briefly passes head to wind and then pops back onto starboard and carries on.  I don’t think that should be allowed but with no definition of “tack” as a verb who’s to say.

 
Revision: I guess the rule 13 title does imply that, nautically speaking, bearing away to close hauled takes place “while tacking” even though the title is not a rule.  I’d still like the first half of a tack to be included in a definition.

When Yellow hails for room to tack, she is saying that she understands that under R 13 she will be the keep clear boat after passing HTW until reaching close hauled but cannot do it unless permitted under R 20. In addition, Blue, by following R 20.2 and hailing ‘You Tack” is saying that she will not interfere with Yellow while Yellow is subject to R 13. 

My conclusion is that room to tack is using the R 13 concept of ‘beyond HTW until close hauled’.

John

Before going to the dictionary, so you could check it. 
I was at a merchant navy training school for five years.
It was there in seamanship classes we were told what a tack is.
There were no implications because there were no applicable rules.
It is putting this in rrs that causes a problem for some, but I have never experienced it.
I f the rrs  does not define, is the default not what I have done?

What of the gybe, wind from one side to the other taking the stern through the wind.

In fleet racing no need for the sail even to be full.

I disagree 13 just defines when rrs deems you should keep clear.
If It did not do this rights would change earlier.
Consider
Tacking to starboard
Or tacking in front of another boat.
13 is neded to push back a change of row.
And switch off 10 11 and 12.

First, nice job Ang for pursuing this.

I have my own opinions on each question answer. But they have already been given in one form or another in this thread. So no need to repeat. 

It does seem that there are multiple valid interpretations / meanings of the word 'tack '.  (Such is the beauty of the English language.) Yet, we only want only one.

Then a learned opinion (Q&A) or even a definitive interpretation (casebook case) may be needed. 

When two possibilities are about equally plausible, a focusing will only go so far. Have we reached that point yet? 

Definition of port tack is that the wind is on her port side. Tacking is therefore a split second while the boat is head to wind (neither port or starboard tack). Consider a leeward boat doing a hard luff to windward. A windward boat must keep clear but if the leeward boat reaches head to wind it is tacking and must keep clear.
I am advocating that tacking is a slit second and does not last from close hauled one direction to close hauled on the other. However to avoid doubt and protests it seems good to have your main setting on a particular side to prove the wind was on the opposite side and the tack was complete. This is a lot higher than close hauled.
Note rule 20.2(c) provides not only room to tack but adds “and avoid her” (also in 20.1)
So to relate to the questions in this thread:
1. John’s question, blue did give yellow room to tack but probably not “to tack and avoid”. Avoid does include room to dip
2 Angelo’s questions:
      1. Blue failed to give room to tack
       2.  Blue did give room to tack and also gave room for yellow to avoid her (by luffing)
       3. Same as 2
       3a. Yes
      3b.   No, or at least not from close hauled starboard to close hauled port. Yes, for the split second she is actually tacking
On the seamanlike reference, I note that luffing head to wind is common practice (eg start line or windward boat keeping clear) so a normal sailing practice, not unseamanlike.

In the diagram for Questions 2, Yellow still has some room before reaching the obstruction. What obligation does Yellow have to time her tack to keep clear of Blue? There is plenty of room for Yellow to time the tack to avoid Blue. Blue's hail of "You Tack" clouds the issue, as she should have just tacked. Now there is the expectation that Blue need to keep clear. Never the less, I don't see how the expectation that Blue must keep clear absolves Yellow of her obligation to keep clear of other boats until she is on a close-hauled course.

I do find it extraordinary that there is a view being expressed hear contrary to every thing I have ever heard on this subject, which removes any need to have a Rule 20!

But I also agree that the RRS need a definition.  And I would suggest that it should follow from Rule 13.

It's fascinating isn't it Matt?

I almost added to my last post another possibility...

The notion that it really isn't an issue.

Consider this:

There are two valid interpretations. Both work, and generally fit into the rule book.

If Sailor A's Club applies interpretation #1, and Sailor B's Club B, 8000km away applies interpretation #2, it is plausible that a SailorA could go a lifetime using  Interpretation #1, never considering the alternative.

Even Sailor A goes to Club B and races, but there is not an incident which raises this topic. He goes home having enjoyed the event thinking nothing of it. It goes like this for years. 

Is there a problem which needs fixing?

Then as the Internet use becomes more prominent, 8000kms separation fizzles into irrelevamce.

Sailor A and Sailor B one day meet in an internet chat forum, proposing the other has been wrong all their lives. Is there a problem now?

Is it worth the time effort and already 260 page casebook real-estate to fix this issue? That's for the rule-makers to decide. Perhaps not.

OK, the rule-perfectionist in me would like this resolved from top down. But, I do wonder what the chance of this landing on my protest desk is.

Incidentally, some people have mentioned the need for a new 'definition' of the verb 'to tack'.

As I see it, definitions are used to deviate/specify a word's meaning for RRS use from general/nautical use.

Our problem is multiple valid interpretations (simply, is it the complete move or the action of passing HTW?) - so casebook, not a definition.

I find the examples somewhat strange as blue responded "you tack" when they had no need to do so.  As it appears they were intending to tack, then all they needed to do was tack in a timely manner and then Yellow would tack to follow them.

Typically a boat responding "you tack" would duck rather than tack.
 

I went back to the Case book and looked at Case 35. To me, it is clear that when a boat hails for room to tack and the hailed boat responds you tack, the hailing boat can tack from a close hauled course on starboard to a close hauled course on port (or visa versa) and avoid the hailed boat. The case uses "seamanlike way" when it discusses the hailing boat avoiding the hailed boat. So in the example #1 and #2 originally proposed, Blue did not met her obligations under RRS 20.2(c). Example #3, Blue did.

The 1993-1996 rules had a definition for tacking and close-hauled:

Tacking  A yacht is tacking from the moment she is beyond head to wind until she has borne away to a close-hauled course.

Close-hauled  A yacht is close-hauled when sailing by the wind as close as she can lie with advantage in working to windward.

The 1997-2000 rulebook included many updates. The definitions tacking, close-hauled and gybing were removed.  Rule 41 in the 1993-1996 rulebook became Rule 13 in the 1997-2000 rulebook.  Rule 13 describes the restrictions on a boat while tacking and releases those restrictions when the tacking boat comes to a close-hauled course. 

Yes we all have to follow ws definitions. When they are at variance with the accepted definition it is good they are removed. Rules like 13 which defines when you get row back are good. The rule title is bad.

Regarding the claim that Rule 20 only lets a hailing boat sail just past head-to-wind, and not to close hauled, here are some thoughts.

Definition of Room:

When Rule 20.1 is invoked, the hailing boat is asking for room, i.e., manoeuvre in a seamanlike way. If a hailed boat only lets the hailing boat head up to just past head to wind, and not close-hauled, the hailing boat will eventually begin sailing backwards, lose control, and possibly collide with the obstruction they were trying to avoid and/or another boat.

I'm struggling to see how sailing backwards, out of control, is seamanlike.

Common usage of Tack:

Much of this hinges on the definition of the verb "to tack", it may be beneficial to examine the common usage of the term by actual sailors, and not just imprecise dictionary definitions written by non-sailors. Looking at the search results for how to tack a sailboat, every video and description has the boat ending on close-hauled on the opposite tack. None of the videos has the boat ending up a past head-to-wind.

So, from that, the common usage of the term "to tack" indicates that the tacking maneuver ends with the boat on close-hauled, not just past head to wind.


Rule 14 and Rule 20:

Looking at John Ball's fourth example, when Blue holds starboard and forces Yellow to turn back to their obstruction, that seems to be a violation of Rule 14.3: Blue is causing contact between Yellow and the obstruction (e.g., a pier) that "should be avoided".

So, even if someone ignores common usage of the word "to tack", only letting a boat go one degree past head to wind is a violation of Rule 14.3, assuming Yellow couldn't reliably duck Blue.

Intent of the rules:

This is admittedly a fuzzier argument, but there is the intent of the racing rules. Rule 14 indicates the rules' intent to minimize contact between boats and objects to be avoided. 

If Rule 20 only gave a hailing boat to go one degree past head to wind, and presumably hold that heading as long as they could, they would soon drift backways, lose control, and then either make contact with whatever they were trying to avoid, or another boat on the course. That appears to contradict the intent of the rules as indicated by Rule 14.

Perhaps there is a case that sheds more light on this?

Look take rrs out ot this they have their own agenda.

To tack is to change from the wind on one side to the wind on the other, period.

Same as I have said for gybe 

Anything else is ws confusing reality.

Rrs 13 is explicit and useful.

DO NOT CONFUSE THE REAL DEFFINITION WITH WS USEAGE 

mike

It seems to me a logical nonsense for RRS13 "while tacking" to be applicable after a boat has finished tacking. If the rule "While Tacking" applies then the boat must be tacking. How much simpler can it get?

Now if you want a hairy scenario, consider a boat that can only tack once she gets up to a reasonable speed.
Yellow calls Room to tack, Blue (some way astern) calls you tack, and then starboard when Yellow reaches close hauled, but Yellow is unable to tack back because she's not yet sailing fast enough.

Jim re Answers ..

That's how I fall.  Mike B and others differ. 

My answers are  (until directed otherwise with an authoritative interpretation).   ...

Q1: Yes a boat is sailing in her "room to tack" as she turns from close-hauled up to HTW.  Therefore a ROW boat is exonerated under 43.1(b) if she breaks RRS 16.1 while doing so. 

Q2: Yes a boat is sailing in her "room to tack" as she turns from HTW down to a close-hauled coarse. Therefore a boat is exonerated under 43.1(b) if she breaks RRS 13/ RRS 15, and by 43.1(c) if she breaks RRS 14 (no injury/damage). 

Q3a: No Blue did not give her room to tack when she forced Yellow to stop her tack in the middle. 

Q3b: Yes, room to tack include space to tack in a normal and ordinary manner for that vessel in the current conditions (Case 21)

Hopefully we'll get a Case or Q&A. 

Take a look at RYA appeal 1982/6 in the RYA case book. I tried posting all the text but it's apparently been rejected. 
https://www.rya.org.uk/racing/rules/case-book

RYA 1982/6
A boat that responds to a hail of 'Room to tack' by starting to tack, but so slowly that she delays completion of the tack beyond a reasonable time, is not tacking as soon as possible after the hail.

It's similar to scenario 3, but especially relevant is this sentence. L was the hailing boat. 
rule 43.1(b) exonerated L for breaking rule 16.1 by bearing away into the collision, since L was taking room to which she was entitled.

Stephen re: "On the seamanlike reference, I note that luffing head to wind is common practice (eg start line or windward boat keeping clear) so a normal sailing practice, not unseamanlike."

A little push back here ...

Though I agree that luffing HTW is a normal maneuver before a start, it is not a normal component of tacking while a boat is sailing to windward on a close-hauled course.  Before a start a boat that luffs is actually not attempting to make-way to windward  ... quite the opposite .. she is attempting to slow her progress (make less way).

How I see it, In def: room, a boat is entitled to space to maneuver promptly in a seamanlike way.  In the RRS, room's "space to maneuver" is in the context of some larger action to do something...

The action that the room is for matters, as it defines that "space". 

Case 21 tells us how to interpret that ...  such that the boat doesn't need to maneuver in an abnormal manner.  It's not "normal" for a boat to slow itself to a crawl in the middle of a tack on a beat to windward.  In a boat that holds momentum, a normal tack is to attempt to maneuver to exit the tack with as much speed as possible. If it's a boat with little or no momentum-retention .. it might be to get through the wind quickly to accelerate on the opposite tack.  Each boat is different .. based its characteristics and the conditions. 

Another RYA appeal that may be relevant to aspects of this discussion is RYA 1973/5
The summary includes
Hailing when safety does not require a substantial course change breaks rule 20.1.
I submit this is at the least strongly suggests that RRS20 is primarily a safety rule. 

Rule 13

I find it very hard to read Rule 13 in any way that doesn't define "while tacking" to mean the period of time "[a]fter a boat passes head to wind... until she is on a close-hauled course." Hence "room to tack" would apply to the period of time that the rules refer to as completing the action of "tacking" -- the end of the period "while tacking". There's your definition of the verb... if that is what the gerund means, then that is what the infinitive means. This seems inescapable to me. It is also consistent with the Rule 13 cases, which use the verbiage "completed her tack" to refer to "she is on a close-hauled course."

Common Usage

It is also the common definition of the term "tacking" in general usage, in my experience. I have never heard anyone refer to "tacking" as only referring to the first half of the turn, or say tacking is complete when you reach HTW (and then some other process starts?).

Purpose of Rule 20

If there is an obstruction that the boats must avoid, coming head to wind doesn't accomplish the goal of avoiding it unless you get onto the other tack. If you luff and don't have enough momentum to get on the other tack, then you haven't been given enough room to avoid the obstruction.

Case 113

This case treats room to tack as room to be close hauled on the new tack, not HTW. Answer 2 states "replying ‘You tack’ is not an option for M in this case." If tacking is just to go HTW, M could say "You Tack" and luff to HTW and W would be forced to come up as well. So that is not the interpretation in use in this case.

Does this interpretation of Rule 20 work? Does Rule 20 work? Is it needed?

I grew up crewing on a Cal 2-27 at Stockton Sailing Club. A lot of the time, the river is 500 feet/150m wide. We would time running the starting line at under 60 seconds. Imagine 6 ten-meter boats crossing that starting line, then coming to the next shore in two or three minutes. This rule would come into play basically every race. The traditional way of thinking about it works just fine. Boats could sail up to the shore, then tack to avoid it. If you were to windward, you would know what was going to happen and were ready for it.

Defining room to tack as "just to turn to HTW" or "one degree past HTW" would break a rule that works fine. For example, it would allow a scenario 3/4, where Blue goes HTW and stays there indefinitely. In practice, this would mean that Yellow would be in a very precarious position. Depending on the shape of the shore, drifting backwards could mean running aground. Slipping onto the wrong tack would definitely mean running aground. If Yellow was expecting Blue to duck and then they didn't, they would have to turn helm toward the shore, possibly quickly -- exactly the angular momentum they don't want to have. Can they avoid blue without going too far? Tricky. Not safe. (For those who say it is not a safety rule, it is very hard to imagine the scenario described above as safer without Rule 20. Maybe we just start sailing in the middle 90 meters and luffing everyone when we want to tack? I just don't see it how it would work in the six-boat scenario above. Plus, it would totally change the racing from normal racing to something weird, see next point.)

Fairness.

With the traditional approach, the boat that is ahead stays ahead. If it just means room to go HTW, the second place boat gets some strange, new -- and less safe -- tactical advantage.

Ok, dead horse beaten... finally, the questions...

Question 1: Yes, Yellow was sailing in the room she was entitled to. 

Question 2: Yes, Yellow was sailing in the room she was entitled to. 

Question 3: So, I read Question 3 as: "Assuming that Blue must give room to a close-hauled course, how fast can Yellow tack? Is there a definition of too fast?"

I think it also bears mentioning that the room required is "room to tack and avoid" (italics mine) the hailed boat. So, not just tack. Tack and avoid.

I'm not really at the level of knowing the whole casebook for this kind of language. But "prompt and seamanlike" seems sensible to me. It treats this "room" like other rooms.

It also has the advantage of working in reverse. It requires Yellow to tack in a normal predictable way. Not too fast, requiring Blue to make an unseamanlike avoiding maneuver. But also not too slow... Imagine scenario 5: Blue is one length to windward and two lengths back. Yellow hails "room to tack". Blue hails "You tack." Yellow starts its tack. Blue falls off a bit to duck. Yellow turns but lets their sails luff. Blue has to quickly fall off or tack to avoid the (now surprisingly parked) Yellow. It is a cousin of the "as soon as possible" RYA 1982/6 case. In this scenario, however, Yellow did start the tack as soon as possible, but Yellow was doing essentially the same delaying action. "Prompt and seamanlike" seems to give the right answer to scenario 3 and this scenario 5 too. Yellow is required to tack as soon as possible in a prompt and seamanlike way given the current conditions.

Question 3a: No. Blue did not give Yellow room to tack and avoid Blue in a prompt and seamanlike way, as Yellow had to stop her tack to avoid Blue. 

Question 3b: Yes. Prompt and seamanlike.

Angelo
I accept the push back and agree your additional comments.
My example  was perhaps poor, as you have pointed out.
I don’t think my original post suggested luffing to a stand still or sailing backwards, that was other posters extending my argument to an extreme conclusion. As you have pointed out, that would be unseamanlike and therefore not comply with the room requirements. It would also not be conducive to the requirement to “avoid her” ( the windward boat).
So I will try again. While racing after the start it is reasonable common to lose speed while luffing a windward boat to “encourage” them to tack in order to gain tactical advantage, or to luff and lose speed to shoot the windward mark.Or to slow up a synchronised tack while being the starboard boat (r13 rights). There are many examples I am sure you could think of which are seamanlike. That is all I suggest, not the unseamanlike stuff or the breach “avoid her” requirement.
I may well be forced eventually to agree with majority that “to tack” extends to “bear way to close hauled” but at the moment I struggle to get past the rrs very clear definition of which tack a boat is on therefor “to tack” is to go from one to the other. The general usage arguments could go anywhere. My Ai says to pass head to wind from one tack to the other which pretty much agreed with the rrs definition. I know there are dictionaries and other stuff that supports the other 2 defintions.
So, for the moment I have to admit that I do not know what “to tack” means. So how can I interpret rule 20?
We can agree that at a minimum, it means passing head to wind, at at a maximum extends to bearing away to close hauled.
I have a train of thought that makes the “to tack” definition less important. If you don’t mind baring with my questions, I may get there in a future post/ question

Jim
Thanks for posting Rya case 1982/6
It is interesting and affirms many of the concepts in the current question.
It also highlights the difference between a starboard obstruction ( in the case) and a port obstruction( in the current post). 
In the case L was not only entitled to r19 and 20 limited room but also to r13 (W must keep clear).
It is not really clear from the decision which room W infringed the most!
What I would like to think thru is the implications in the current post that the yellow boat must comply with rule 13 ( ie keep clear if both boats are tacking) while the blue boat must give her room to avoid the obstruction, room to avoid her, and room to tack (nothing more than that).

Stephen  re:  "but at the moment I struggle to get past the rrs very clear definition of which tack a boat is on therefor “to tack” is to go from one to the other."

It is not "very clear".  You may have missed the original thread here, where I initially argued for a verb RRS definition addition for "to tack" (and I started with the "RRS13-interpretation", as we've started to refer to it. Our friend Rob O convinced me otherwise in his comments ... I'm now in the board-to-board camp).

Tack is a noun and a defined term when used in the RRS italicized.   When "room to tack" is used, "tack" is not italicized, so it reverts to "ordinarily understood in nautical or general use."  We have shown there are 3 competing ideas of how this is "understood" by knowledgeable and thoughtful sailors (passing-HTW, RRS13, and board-to-board).

So .... you are sailing on your boat and you tell your crew "prepare to tack" (crew gets off rail and on the sheets) .. then you call "tacking" .. the moment just prior to when you start luffing up to and past HTW .. then down to the other side close hauled. I think most skippers/crew understand that use of "to tack".

Now imagine you are on your boat ... crew is on the rail, you start heading up to HTW and after you start turning then call "prepare to tack" ... and just as you reach and pass HTW you call "tacking!" .. then after passing HTW pause (not going to close-hauled) ... slowing ... and say to your crew ... "great tack people". 

I'd imagine your crew would be very concerned :-)

Jim the only aspect that is clear in def: tack, is the noun use of the word when determining which tack a boat is on. The def is about what tack "a boat is on". 

It is a static determination of the state of the boat. 

"To tack" is a verb ... it is a dynamic action and "tack" is not italicized. 

What a fantastic thread!  Lot's of well thought out input from smart minds.

To put it bluntly, the prime question is, 'what does 'room to tack' mean'?

Do we apply a probably more technically correct 'nautical' use?? - To swap the wind from one side to the other by turning the bow through the wind.  Nothing more than passing HTW.

Or a more 'general' but commonly-used use? - From best upwind sailing on one board to best upwind sailing on the other board?

The RRS introduction doesn't favour one or the other. It says.. "Other words and terms are used in the sense ordinarily understood in nautical or general use."  (OK - let's not dissect what that means... my point is that 'tack' is used with a wide array of meanings...)

Actually, either may fit, or either may have issues.  So folks can go round and round arguing one is correct and the other is not. 

When this happens I prefer not to get drawn in.  It's rather pointless.  (Of course, I have my private opinion, but that's not important.)

WS needs to simply tell us which interpretation to use, and then we all use it.

----------------------
I've watched this and other threads go back-and-forth for sometime.  The cases for all different sides of the coin have been well presented.  But without getting closer to agreement.

I find the title of RRS 13 a distraction.  A red herring.  It's just a name given to the rules contained in r13.  Not a definition of what a tack is.

Well, quite some time ago Angelo spotted the difficulties and presented us with some questions at the beginning of this thread - - not really for us to try and answer methinks, but with the intention to get feedback on the questions themselves as questions to present to the WS Q&A panel.  I admire Ang's persistence here.

Perhaps now we can focus on the structure of those questions, particularly, what must be asked to get, first, a learned opinion as to which interpretation to use - -(what do some respected rule guru's think?), and if that's not enough to convince the others, to get an authoritative interpretation.

What question should be asked to force a side to be adopted by WS so that we can all note it, and get on with our lives.

So...To Nautical use or To General use?  That us the question.
----------------------
My take:

I think Ang's Q1 and Q2 would illicit an answer to the prime question.  I don't see possible improvement. (Perhaps just remove the words 'Assume'.)

On Ang's secondary question - How fast / how long / how slow is 'room-to-tack'? - I think this is addressed in the RYA Appeal 1982/6.

Angelo
Yes, I did notice your early reference to another thread and no, I had not read it, nor could I find it.
I could obviously benefit by reading it but I just have a phone while travelling, so it’s difficult.
I have had further thoughts overnite, some inspired by the new comments here. I will try and put them into words later today

Overnite,  think I figured out what “tacking” means sufficiently to understand rules.
Can I make a series of points? And if the points are valid they lead to a conclusion.
1. The loose term tacking involves turning up, passing thru HTW, bearing away to close hauled.
I think, without dispute and (hopefully) unanimous agreement we can say that a boat that passes head to wind is somehow engaged in tacking. 
Therefore rule 13 is triggered at least from the moment thatHTW was passed and rule 13 remains applicable until r13 says it no longer applies. That is, when the reaches a close hauled bearing.
2. Priority of rules relevant to room. There was a post here discussing the priority of room over specific rules and when rules “turn off” or “turn back on”. I think the conclusion was that the rule always applies as did the room requirement. The conflict being resolved by the rule being limited to the minimum extent possible to allow whatever room was permitted
3. WS case 35 makes it clear that if  L is able to tack and dip W, she must do so. Ie observe rule 10 and acknowledge that W has left sufficient room for L to pass behind her.
4. If both boats tack simultaneously R13 requires the port boat (yellow) to keep clear of the starboard boat (blue). Blue remains liable to provide a path for yellow to “avoid her” which is not particularly difficult throughout the tacking process ( sorry, the r13 process).
Importantly this allows blue to control the speed of the tack and reach close hauled when sh chooses to.
5. Prompt and seamanlike in the definition of room and in case 21 is primarily an obligation placed on the boat entitled to room, to force her to cease breaking whatever rule she is breaking as soon as possible in order to restore the rights of theROW boat. References to other boats requiring them to allow the room boat to manoeuvre promptly and in a seamanlike manner are mainly used to determine the minimum amount of room that is required and highlight the room boats obligation not to use more room than that.
Case 35 highlights that L would have liked her room to allow her to continue on port forcing starboard to tack but the appeal decision forced her to take the slow route and dip.
I have just read Angelo’s post on “promptly” and agree entirely. I could really delete my point 5 above