... after 15 sec .. describe what is happening to the sails and the horizon on the Weta.  Then in the seconds just prior to impact, what is happening with the horizon?  Finally, use that info to translate the actions of the boats in terms of the RRS and the rules that apply.

If the trimaran was in the zone when the 29er passed head to wind, 18.3 applies and the 29er is required not to cause the Weta to sail above close hauled.  Therefore the 29er breaks 18.3.  She certainly does after the luff and most likely did before the luff.  I do not think 18.4 applies, looking at boats (still on starboard) in front of the Weta after she bears away.

If the 2021 rules apply, the zone is three hull lengths so the Weta's bowsprit would not count.  The 29er was nearer the mark so her hull length defines the zone.

The Weta is still bound by rule 11.  I think she had room to keep clear and could have luffed.  She was not forced to break 11 by the 29er's breach.  Both, therefore, DSQ.  I think the 29er's luff was the result of a broach so not deliberate.  

I think the 29er, RoW boat but with an obligation under 18.3, did not act to avoid contact when it was clear (to the 29er if they had been looking) the Weta was not keeping clear.  Hence 49er broke 14. No exoneration because there was damage.  It was reasonably possible for the Weta to have luffed so she broke 14 too.  29er's loss of control no excuse.

After the 29er tacks in the zone she is clear ahead and gains ROW under R 12. As Weta entered the zone on stbd, R18.3 is applicable, but Weta was not forced above close hauled, so not broken.
 As the boats leave the mark, the 29er luffs and contact occurs between stern of 29er and bowsprit of Weta. 29er breaks R 16.1 as ROW altering course without giving room to keep clear.

John

0:15 - 29er completes tack; Weta heads up slightly (compare mast to far shore), but sail never luffs, RRS 18.3 not broken. 
Both boats are past the mark ~0:23 seconds and start to bear away.  Weta must keep clear of 29er (either RRS 12 or 11, depending on overlap situation).  RRS 18 no longer applies.
At 0:24, Weta skipper looks aft (literally head down into the boat) while bearing away as 29er starts to luff.
At 0:25, Weta skipper notices 29er is luffing and continues to bear away.
At 0:26, contact w/ damage.
If the boats are moving at 8 kts, that's 4.05 m/s or about 1 boat length / second.

Had the Weta skipper paid attention all the time, he would have had enough time / room to keep clear.

DSQ Weta on RRS 11 and 14
29er does not break 14 since it was not reasonably possible for her to avoid contact.

It looks like the 29er tacked in the zone onto starboard, clear ahead of the weta and before the weta reached the zone. The weta, fetching the mark on starboard was not forced above close hauled and no rule was broken. The 29er was ROW boat AND had mark room. After passing the mark, the weta was too close, became overlapped to windward as it bore off, making contact with the 29er, and failed to keep clear as per RRS 11Definition of Keep Clear, particularly B) when the boats are overlapped if the ROW boat can also change course in both directions without immediately making contact. 
I think the weta misjudged its proximity to the 29er and bore off prematurely. The weta's situation was compounded by the unexpected move of the 29er but the fact remains, the weta was obligated to keep clear.

Matt .. the only quibble I'd make to your write-up is #2.  It appears to me that Wetta is abeam of the mark at 0:23-0:27.

Your description brings up an interesting question regarding when 18.3 "turns off" now in the new quad. 

In 18.3, there are 2 possiblities of which boat gets mark-room.  If the stb-always boat is outside, she owes port-taker mark-room.  If the stb-always boat becomes overlapped inside, then port-taker owes her mark-room.

In this instance, Wetta is first clear astern and then outside and therefore 29'er gets mark-room .. and 29'er is past the mark at 0:26, so one could argue that mark-room has been given to the boat owed it and 18.1 turns off 18.

On the other hand, had Wetta successfully ducked the 29er and got between her and the mark, 18.3 would provide Wetta mark-room .. but if it was the 29'er who first got the mark-room under 18.3 and she was given it, does 18.1 turn off 18.3 before Wetta can get inside?

One might read 18.3 such that 18.1 can't turn off until both boats under 18.3 have exhausted their opportunity to mark-room.  If that's the proper interpretation, then 18 is still on.

It's not possible to tell from the perspective of the Weta video whether the 29er tacked in the zone or not. But even downspeed coming out of a tack I think the 29er would have transited the zone in 3-5 seconds. It was almost 10 seconds from the time the 29er completed her tack until her bow was at the mark so I'd conclude that the 29er completed her tack outside the zone and 18.3 was not on.

Even if it was, the Weta doesn't appear to head up in response to the 29er as she approaches the mark. There's no significant movement of the horizon, no pull on the sheets or push of the tiller, no apparent luff of jib or main. The Weta driver may think he headed up above close-hauled but the video evidence indicates otherwise.

It isn't clear from the video perspective whether the Weta established an overlap before the 29er reached the zone or not but since the Weta was windward boat when the overlap was established I'm not sure that matters.

After passing the mark, the 29er's luff/roundup rotated her stern away from the Weta. I don't believe there's any rule that required the 29er to bear away after the mark even if she'd maintained control. So in my view the contact was caused by the Weta bearing away.

So I'd say:

Wait a minute. If 18.3 is invoked when the 29er tacks then the 29er can never get mark room as 18.3 turns off 18.2 and only potentially gives mark room to the Weta if she dives inside.  The 29er has to rely on rule 11 to protect herself while she rounds.  I’d also say that the 29er luff was not very violent and the weta should have been able to avoid but made no attempt, in fact bearing off into the 29er. Penalize Weta rule 11.

As for 18 turning off. Since no one was owed mark room, it couldn’t have been given.  I’d think 18 continues until both boats leave the zone.

It all looks pretty simple to me and I agree with Matt.  As far as the incident goes it is a pure W/L.  Whether 18 is on or off is not relevant as 18.3 was not broken and room was given, both before the incident and the mark was not a factor in the incident.  Wetta is DSQ for 11 & 14.  29er does not break 14.

John C re: “Whether 18 is on or off is not relevant as 18.3 was not broken and room was given, both before the incident and the mark was not a factor in the incident.”

I agree. I was just trying to see if I could entice anyone to follow me down a new rabbit hole ;-)

After watching the video, the Weta knew the 29er was there and bore away without regard to the course of the 29er. It looks like he forgot his bow sprit was there. During the incident the 29er does not appear to luff past head to wind and lose rights. I don't agree that the 29er tacked onto port. At the time of the incident both sails had rounded shape and boom of 29er was on port. Weta DSQ. Nothing 29er could do to avoid collision as Windward bore away into the 29er. Weta breached 14 by not avoiding collision. 18 irrelevant.

Looked to me like the Weta started to bear away, the helm looked into that bilge to adjust his sheets and as he wore away his bow sprit struck the stern of the 29er. Does anyone agree?

The 29er tack was probably on the edge of the edge of the Zone, but Weta didn’t have to alter course let alone sail above close hauled and the 29er passed the mark clear ahead of Weta with Weta gaining. 

I think that was weta’s problem - sailing higher and overtaking the 29er, when she bore away she had, unbeknown to her skipper, established a slight windward overlap and when Weta bore away her bow sprit struck the 29er.

Rules applicable - RRS 11 and 14 if the above scenario applies. DSQ Weta.

Phil, I agree. Basically Matt’s analysis as well. 

Given the evidence, I think it’s more likely than not the PC will find the 29 tacked in the zone, but in the end didn’t matter.  

I think Tim and Bob Lewis have got it right, and Phil M of course.

This is an excellent example of the limitations of video and photographic evidence.  It’s good for events:  tiller up/down, head turned, sheet trimmed etc, fine for changes in course of the boat the camera is on, less good for other angles, and absolutely hopeless for distances along the axis of the lens, hence the difficulty with distance to the zone or mark.

I broadly agree with Tim’s time and distance analysis, noting that it's when 29er passed head to wind, not when she reached close hauled that matters.

P was close hauled, or just below @16, she was bearing away round the mark @23, that’s 7 seconds.  I don’t think she’s going to be doing anything like 8kts, prolly less than 6kts.

 

@5kts, a 14 ft boat takes 1.7sec to travel 1BL so 5.1sec to travel 3BL, the radius of the zone.  4BL in 6.8 sec.

 

OK, I’m convinced 29er reached close hauled outside the zone.

29er began luffing into her tack @11, and was head to wind @12, so that's another 1 or 2 BL away.

if necessary applying last point of certainty:  she wasn’t at the zone.

 

No rule 18.3.  29er is entitled to mark room under rule 18.2.

 

I also agree that Weta never sailed above close hauled, so even if it did apply, 29er did not break rule 18.3.

 

If rule 18.3 had applied, then rule 18.2 did not, and only the Weta could have become entitled to mark-room by getting overlapped inside the 29er.

 

Which, as Bob Lewis explained, disposes of Angelo’s rabbit hole.  If rule 18.3 applies and the starboard tack boat never gets overlapped inside, there is no point at which mark-room has been given, rule 18.1 last sentence does not switch rule 18 off and Port’s obligation to not cause Starboard to sail above close hauled continues until both boats leave the zone, when rule 18 ceases to apply

John re: “Angelo’s rabbit hole.  If rule 18.3 applies and the starboard tack boat never gets overlapped inside, there is no point at which mark-room has been given, rule 18.1 last sentence does not switch rule 18 off and Port’s obligation to not cause Starboard to sail above close hauled continues until both boats leave the zone, when rule 18 ceases to apply”

Certainly that interpretation is consistent with how 18.3 applied in the last quad.  It’ll be interesting to see if this gets clarified with a case/appeal in light of 18.1(LS).  

Angelo,

I agree that if S never gets overlapped inside, the continuation of rule 18.3 until boats leaving the zone is the same in 2021 rules as in previous rules.

How would you interpret the 2021 rules otherwise?

John, 29er has to complete her tack before she enters the zone to avoid 18.3 jeopardy, doesn't she? 

Based on time & distance I think the video shows she did in this incident. 

Rule 18.3 does not require a boat to complete her tack before she enters the zone. The test is "If a boat in the zone of a mark passes head to wind from port to starboard tack and is then fetching the mark", it does not require a boat to complete her tack before she enters the zone.

John re: " How would you interpret the 2021 rules otherwise? "

I agree that's how we should interpret/apply it given how both 18.1 and 18.3 are written.