I disagree with your answer to #11. It appears that Green does not break R 13 when she tacks and also allows room under R15 when ROW changes. 
18.3 applies, as Red entered the zone already on stbd and Red must stay clear as windward boat under R11. R18.3 does not give mark room to either boat. If Red has to sail above close hauled to clear Green, then Green breaks 18.3. 

John

Even though it's "unlikely that R will have to sail above close-hauled", the conditions for 18.3 are met and 18.3 is on. Which means 18.2 is off. 

R must keep clear of G (11) and G must give R room to keep clear when altering course (16.1) but G must not cause R to sail above close-hauled (18.3)

Tim, John: That makes perfect sense, thank you. I have updated the page.

I'm not sure but 18.3 may apply until red has left the zone and not 'left the mark' as in the 3rd para.

I'm not sure 18.3 is turned off by the last sentence of R18.1 as no mark room has been given. This means red must not be caused to sail above CHC until she has left the zone.

Also note that if red tacks to starboard by passing HTW inside the zone, 18.3 does not apply and green will have markroom under 18.2a after green passes HTW into inside overlap.

Note that your scenario and the Call Book's are significantly different.
In yours, S holds a steady course.
In the Call Book, P has opportunity to tack and clear the mark until S bears away.

Johan, depending on what you are trying to demonstrate, you might want to alter your drawing slightly.  It all depends on the intention behind this instruction. 

Here is how I see it based upon your drawing ….

When I look at this scenario, Green just reaches the layline at #2. We can assume the laylines indicate the close-hauled course to windward.

Red holds her course from #1 to #2, entering the zone on starboard.  RRS 18.3 applies and RRS 16.1 does not.

Red is ROW v Green from #1 until #2 until Green finished her tack by reaching a close-hauled course and 13 turned off.  Red does not owe room to keep clear or mark-room to Green from #1 to #2.  Red is thus under no obligation to alter course before #2 except to avoid contact if reasonably possible by RRS 14.

At #2, Green becomes ROW just as 13 turns off and 11 and 15 turn on.  At #2, Red can not turn to windward to keep clear of Green as her stern will rotate into Green, therefore Green did not initially give Red room to keep clear when Green became ROW. 

Penalize Green for breaking RRS 15. Green was not sailing within room or mark-room she was entitled to, so Green cannot be exonerated for breaking 15.  

If contact occurred, both Green and Red break RRS 14, as it was reasonably possible for both Green and Red to avoid contact. We then have to look for damage to see if Red is exonerated for breaking 14. 

Had Red altered course before #2 to avoid contact, Penalize Green for breaking RRS 13. 

PS … An important note about RRS 18.3, is that “mark room” only shows up once … and it endows the starboard tack boat with mark-room from the tacking boat under a specific circumstance.  “that boat” in RRS 18.3 is the boat that entered the zone on starboard and “her” is the boat that tacked. 

There is no part of 18.3 that ever gives mark room to the boat that tacks from port to starboard inside the zone. 

Hi Johan,

In your diagram for #8, I have some comments to help Red- we get this situation quite frequently at my local pond. 

Best action for Red is to start to hail for room well before reaching the zone to give all the outside boats room to respond. Red could even gybe to stbd well before the zone and push the other boats out wider to create room- just avoid breaking R 15 or 16.1 after the gybe.

John

Angelo, the intent of #11 is this show that tacking in the zone does not strip that boat of all rights. Often we hear a skipper on our local pond saying "you tacked in the zone!" and colliding. This I think is the result of someone misunderstanding rule 18.2.d and that then became folklore within the club. I have separated the boats in the picture to remove rules 13, 14, 15 and 16.1 from the situation.

John, thank you I have added your comments to #8.

Johan, when reading your #11 narrative, you might consider to flip the script a bit. 

As you say, if G is ROW by 11 or 12, she still retains her “rights” as a ROW boat, BUT in addition to her  limitations from Part 2, Section B (typically 14, 15 and 16.1 come into play), 18.3 ADDS more limitations to Green’s ROW. 

When G is keep clear by 11 (Red gets inside overlap to leeward), Green owes Red mark-room. Note that 18.3 does not include an escape-clause for Green if Red’s inside overlap happens so close to the mark and/or Green that Green is unable to provide it (18.2 does not apply, therefore 18.2(f) does not apply). 

Angelo, that does indeed read better.

Thank you all for your help!