I think if the boat passing on the hails, hails "room to tack" then the next boat has to respond by tacking immediately or hailing "you tack".
If the hail was invalid here the hailing boat may be penalised if the jude considers she did not need to make a substantial alterations of course, as she was further from the shore.
It is unlikely she will be challenged however, as there is a boat to leeward of her.
This is a safety rule so if a boat hails correctly, you must respond.

Let me make sure I understand.

I agree that middle should theoretically not hail here until she either (a) hears a valid hail or (b) needs room herself.

This gets muddier as there become more boats, because the rule requires her to give others time to respond (including passing the hail along). With just three boats it's a little clearer, though the reality is that hitting the EXACT right moment might not be quibbled with by a PC/jury.

As sailors who are *cough* known for having common sense and good judgement, I think it should be on us to take the situation into consideration and base how early in the sequence of events to hail.  The number of boats that may have to react to the hail, how fast things are happening, the noise level, etc. etc. should all make the hailing party pad the time that they think is necessary for everyone to understand the situation, assess the situation, and react in a safe and timely manner.

When I look at 20.2(b), a boat has been 'hailed' and 'shall respond even when the hail breaks rule 20.1'.  20.3 allows a hailed boat to hail another boat because they have been 'hailed'.  20.3 makes no mention about the validity of the hail, just that the boat has been hailed, so she can make a valid hail for room even though the hail she received is invalid.

20.3 also says that the requirements of 20.1 still apply to the hailed boat when making her hail (required words, arm signals if required, etc.) but the conditions (approaching an obstruction and close-hauled) do not.  What I find interesting is that the condition about fetching a mark will not apply either.  Consider this situation where a mark is also an obstruction:

Blue can hail Yellow for room to tack.  Yellow can now hail Green and ask for room to tack even though Green is fetching the mark because the conditions of 20.1 do not apply to Yellow's hail to Green per 20.3.  This makes it critical to know if Blue hailed Yellow before Yellow hailed Green.  If Blue hails first then Yellow can hail Green.  If Yellow hails Green before Blue hails Yellow, then Yellow's hail is invalid as she is not passing along a hail, but making her own and therefore the conditions of 20.1 apply.

John C., I’m not following you. The Q&A says “In order for rule 20 to apply, a hail that includes the words ‘Room to tack’ needs to be made.”  And the Aussie appeal follows this.  Rule 20 is not in play. So it makes no sense to discuss any other sections of rule 20.  I would say that when they say “hail” in this rule they mean a hail of “room to tack”.  I believe that was the point of the rule change.

To answer John Ball, as above I’m in agreement with Michael that it’s as if no hail has been made and so boat 2 can only make a new hail on their own accord following all the criteria.  Usually I think the 2nd boat would have to sail a bit closer to the dock before making a hail for themselves.  The first boat would be left to let out their sails and luff.

And what about rule 14 if the hailing boat then runs aground or hits the dock is the unresponsive 2nd boat violating rule 14 by causing contact with an object.  Personally I think not as the cause is the lack of rule knowledge by the first boat and/or their failure to slow down and let the other boats go by.

I guess this means that I think the Q&A has problems and is not well thought out.  Unlike rules 18 and 19, there is nothing in rule 20 that says when the rule applies, it always applies.  The Q&A contradicts the plain language of the rule.  Consider that if a valid hail must be made for rule 20 to apply in its entirety then what is the purpose of rule 20.2(b)?

If you consider an invalid hail the equivalent of not making any hail at all as the Q&A suggests, if Blue makes an invalid hail to Yellow, then Yellow makes a valid hail to Green and then Green tacks and protests Yellow, should a PC decide that Yellow broke 20.1?  I think the answer is yes.  It is also the same answer that a PC should come up with if Yellow hails before Blue hails because until Blue hails Yellow cannot fall back on rule 20.3.

Using the logic from the Q&A, it is only a valid hail from Blue that allows Yellow to hail Green.  Without Blue, Yellow could not hail Green for room to tack because Green is fetching the mark.  If Yellow makes a valid hail then she breaks rule 20.1.  If Yellow makes an invalid hail then she doesn't break rule 20.1.  The validity of Blue's hail will determine whether Yellow broke a rule or maybe not.

Suppose Blue makes a valid hail to Yellow and Yellow makes an invalid hail and Green tacks and protests Yellow.  According to the Q&A, Yellow does not break rule 20.1.

Huh?  Try explaining all this to the sailors.

This is the truth table for my situation:

Blue's hail            Yellow's hail         Blue breaks 20.1 w.r.t Yellow        Yellow breaks 20.1 w.r.t. Green
Valid                       Valid                      No - rule 20.1                                   No - rule 20.3 removes fetching condition allowing a hail
Valid                       Invalid                   No - rule 20.1                                   No - Q&A answer 1
Invalid                    Valid                      No - Q&A answer 1                          Yes - rule 20.1 for Yellow combined with Q&A answer 1 for Blue
Invalid                    Invalid                   No - Q&A answer 1                          No - Q&A answer 1

All in all, this simply strengthens my personal feelings about rule 20.  Situation 2 of the Q&A is exactly what would happen if rule 20 didn't exist.  Fortunately, the Q&As are not binding.

Additionally, you can dig deeper into the possibilities.  Rule 20.1 requires certain conditions to be met along with a valid hail.  Let's look at the combinations:

Boat's hail         Conditions of 20.1 met?     Breaks 20.1 w.r..t hailed boat
Valid                   Yes                                        No - rule 20.1 requirements met
Valid                   No                                         Yes - rule 20.1 requirements not met
Invalid                Yes                                        No - Q&A answer 1
Invalid                No                                         No - Q&A answer 1

I don’t know John, you might be making this too simple.  Where is the column: “Blue breaks rule 20.1 with respect to Green”? It seems to me that Case 113 makes Green a boat hailed by Blue if Green can hear the hail, so they will have to respond to Blue’s hail and Blue should be penalized.

I wouldn’t bet against the Q&A becoming a Case after reading the Aussie appeal with Richard Slater and his group of IJ’s and NJ’s on board.

I agree that rule 20 doesn’t really turn off but I think the interpretation is that everywhere you see “hail” after the first paragraph, you need to replace with “compliant hail”.  I think the rule writers were lazy and just assumed that since we had defined what the hail should be that’s what hail means for the rest of the rule.  Otherwise “lets go for beer” is a hail and they seem from the submission to want to stop that nonsense. 

From my observation, the rule works well for two boats but is mostly impossible for 3 or more.  In high speed radio sailing, passing on a hail and waiting for replies down the line is a joke idea.  You will see groups of boats tacking off and making room at the shore but it’s not from rule 20 hails beyond maybe the first one.  They do it out of gentlemanly behaviour.

When teaching this rule now, I think is will be simple “you will use these exact words or you will luff up, slow down and take a distance penalty”.

Oh and you asked the purpose of 20.2(b) – that’s for when the hail is worded correctly and becomes a “hail” but 20.1(a) or (b) are not satisfied.
They are rule breakers because the sentence says “shall not” … no “mays” here.