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Port Layline - Rule Check In

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Forum Name: Racing Rules
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URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=13774
Printed Date: 15 Jun 21 at 4:41am
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Topic: Port Layline - Rule Check In
Posted By: redman
Subject: Port Layline - Rule Check In
Date Posted: 21 Apr 21 at 8:21am
Hi,

There have been a few times recently where the fleet have ended up largely on the port lay line.  It's amazing how many disagreements can end up once this happens, and I have realized I am not entirely sure of every possible out come.  I thought I would take the opportunity to document my understanding  here and have the brains trust critique my understanding:

Situation

Outside (O) is sailing on Port on the Port lay line say 15 boat lengths from the Windward Mark (WM) to be rounded to Port.  Inside (I) approached on Starboard and O is forced to duck I to comply with rule 10 (Port Starboard).  I then tacks on to Port tack.  No rules have been broken to this point, and both boats are sailing on port, on or very close to the port lay line, and 10 to 15 boat lengths from the WM which both boats must tack to round on Starboard and leave to port. 

As I understand it, there are now 3 possible (most likely) scenarios.  Here is my take on what happens under each:

Scenario  1 - Both boats reach the Zone with I inside overlapped of O.

In this case O clearly has to give room to I under Rule 18.2 (B):

18.2 (B) If boats are overlapped when the first of them reaches the zone, the outside boat at that moment shall thereafter give the inside boat mark-room. If a boat is clear ahead when she reaches the zone, the boat clear astern at that moment shall thereafter give her mark-room

My understanding is that "thereafter" I is entitled to "Mark Room", and that Mark Room allows her to tack, sail to the mark, and sail around the mark as per this 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 or pass the mark as necessary to sail the course without touching the mark. However, mark-room for a boat does not include room to tack unless she is overlapped inside and to windward of the boat required to give mark-room and she would be fetching the mark after her tack.

So far so good.  The confusion that appears to happen here is that Rule 18 seems to shut down (via Rule 18.2(d)) when one, or both, of the boats tacks on to STB.  Assuming I tacks first it should be OK, as O would then follow, but I have often seen instance where O will tack early and try to duck under I, now claiming an inside overlap on the later tacking I on the basis that the original rule 18 situation no longer applies as one or both boats have tacked. 

18(d) Rules 18.2(b) and (c) cease to apply if the boat entitled to mark-room passes head to wind or leaves the zone. 

Rule 18.3 would not apply here as no boat completes its tack from PT to STB before entering the zone.

Scenario  2 - Both boats reach the Zone with I to windward of O but with no overlap of O (O is to leeward and ahead).

O is clear ahead and has rights under 18.2(b).  However, as soon as she passes head to wind she no longer has any rights as 18.2(d) switches off 18.2(b).  So it is now port starboard (rule 10) and when tacking on to Starboard O has to make sure that she observes Rule 15 and gives I Room to keep Clear:

15 ACQUIRING RIGHT OF WAY When a boat acquires right of way, she shall initially give the other boat room to keep clear, unless she acquires right of way because of the other boat’s actions.

I think this one is quite interesting.  As both boats are in the zone, we could assume they are quite close, and any tack from O on to STB would break rule 15.  However, if far enough ahead, O could argue that it has left enough room for I to duck O after tacking on to STB.

Rule 18.3 would not apply here as no boat completes its tack from PT to STB before entering the zone.

Scenario  3 - Unconsciously, or consciously, O ends up below the lay line and tacks on to STB (passes head to wind) outside the zone.

Here, 18.3 comes into play.  I has little rights.  However, O, I assume, still has to observe rule 15.  I've seen several cases  where O tacks and I then tacks to avoid a PT/STB collision.   O then claims an 18.3 violation.  I don't like this approach as O is trying to claim that it is so certain that it completes it's tack outside the zone and I completes it's tack inside the zone.  I would want to pretty sure O could prove this - the most likely event being that both boats are either in or out of the zone.  


18.3 Passing Head to Wind in the Zone If a boat in the zone of a mark to be left to port passes head to wind from port to starboard tack and is then fetching the mark, she shall not cause a boat that has been on starboard tack since entering the zone to sail above close-hauled to avoid contact and she shall give mark-room if that boat becomes overlapped inside her. When this rule applies between boats, rule 18.2 does not apply between them
There is of course a scenario 4 where both boats sail below PT lay line and tac on tot STB outside the zone.  This is then a normal STB lay line rounding and covered well elsewhere.

Scenario 4 - would be where both boats tack onto STB lay line outside the zone.  This is a standard STB lay line and covered elsewhere.

I've seen other discussions of the above 3 scenarios where rule 18 switches off when one boat tacks, but switches back on when the second boat tacks.  I've never understood this logic.  Surely once the lead boat enters the zone we then follow the "thereafter" condition in 18.2(b).  Trying to switch rule 18 on and off while boats are tacking around a mark seems quite haphazard.  

Happy to be critiqued as appropriate - just trying to understand as best I can.

Thanks.



-------------
REDMAN



Replies:
Posted By: jeffers
Date Posted: 21 Apr 21 at 9:42am
You need to remember that I is the keep clear boat once she has tacked on to Port (Rule 11 or 12 depending on whether there is an overlap or not).

This does not mean that O can do what they like though as the RoW boats actions are restricted (to some extent) under Rule 16.1 so they cannot just change course if, in doing so, they would cause I to have to take immediate avoiding action where they were previously keeping clear. (read the definitions that govern this as they are as important as the rules).

Rule 18, in some respects, is irrelevant as it comes down to when O can tack rather than when they want to tack. Obviously O will want to tack as soon as they reach the layline but they cannot if in doing so the Keep Clear boat can no longer keep clear. 

O will potentially fall foul of Rule 13 (while tacking) rather than Rule 15 (as they already have right of way they just need to keep clear whilst tacking).

Rule 18 is governed by the final position and can change multiple times in the zone as boats tack.

The simple onus is that anyone on Port tacking in the zone for a WW mark needs to be careful and sure they have the space.


-------------
Paul
----------------------
D-Zero GBR 74


Posted By: redman
Date Posted: 21 Apr 21 at 11:01am
Thanks Jeffers - that is some real good feedback. I didn’t pick up that outside is already ROW when they are both on port and outside of the zone. So under scenario 2 I can certainly see why it is rule 16.1 instead of 15. But other then that it is the same out come just under a different rule.

Under scenario 1 inside clearly become right of way boat when they hit the zone. I can see why 18.2b is switched off when inside tacks because of 18.2 d. But I get confused as to why 18.2b switches off if outside tacks. I get that 18.1 a or b says they have to be on the same tack. But then why would 18.2 d exist?? and 18.2 b says “thereafter” which could mean anything, but I would like to thing means thereafter rounded the mark!

-------------
REDMAN


Posted By: jeffers
Date Posted: 21 Apr 21 at 4:26pm
The advice of 'take the mark away' in situations like this simplifies things a great deal. It all comes down to can O tack without infringing I (or making it impossible for I to keep clear) then is becomes a simple port/starboard situation. 

I is free to tack whenever they wish (subject to other boats of course) and it can be a good tactic to duck then tack as it can put you in the driving seat at the next mark despite being the keep clear boat.

Brass or someone with a far better in depth knowledge can answer the other rule 18 questions. Tacking in the zone definitely complicates things, even more so if it is a starboard mark rounding.


-------------
Paul
----------------------
D-Zero GBR 74


Posted By: Brass
Date Posted: 22 Apr 21 at 11:19am
Originally posted by redman

Hi,

There have been a few times recently where the fleet have ended up largely on the port lay line.  It's amazing how many disagreements can end up once this happens, and I have realized I am not entirely sure of every possible out come.  I thought I would take the opportunity to document my understanding  here and have the brains trust critique my understanding:

Situation

Outside (O) is sailing on Port on the Port lay line say 15 boat lengths from the Windward Mark (WM) to be rounded to Port.

15 BL away, not a whisker of mark-room in sight.

  Inside (I) approached on Starboard and O is forced to duck I to comply with rule 10 (Port Starboard).  I then tacks on to Port tack.  No rules have been broken to this point, and both boats are sailing on port, on or very close to the port lay line, and 10 to 15 boat lengths from the WM which both boats must tack to round on Starboard and leave to port. 

As I understand it, there are now 3 possible (most likely) scenarios.  Here is my take on what happens under each:

Scenario  1 - Both boats reach the Zone with I inside overlapped of O.

In this case O clearly has to give room to I under Rule 18.2 (B):

18.2 (B) If boats are overlapped when the first of them reaches the zone, the outside boat at that moment shall thereafter give the inside boat mark-room. If a boat is clear ahead when she reaches the zone, the boat clear astern at that moment shall thereafter give her mark-room

My understanding is that "thereafter" I is entitled to "Mark Room", and that Mark Room allows her to tack, sail to the mark, and sail around the mark as per this 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 or pass the mark as necessary to sail the course without touching the mark. However, mark-room for a boat does not include room to tack unless she is overlapped inside and to windward of the boat required to give mark-room and she would be fetching the mark after her tack.

Note, she is not entitled to room to tack until she is able to fetch the mark on starboard, and the whole of her mark-room entitlement goes off when she passes head to wind.

So far so good.

Yup

  The confusion that appears to happen here is that Rule 18 seems to shut down (via Rule 18.2(d)) when one, or both, of the boats tacks on to STB.

It ain't confusing.  Its what rule 18.1 says.

  Assuming I tacks first it should be OK, as O would then follow, but I have often seen instance where O will tack early and try to duck under I,

So, O, right of way, leeward, with rule 16 obligation to give I room to keep clear when she changes course, luffs into her tack.

O passes head to wind from port to starboard:
  • she is immediately required to keep clear of I (rule 13)
  • rule 18, in its entirety ceases to apply (rule 18.1(a) or (b)).
O reaches her close hauled course on starboard:
  • boats are still on opposite tacks, so mark-room isn't on
  • she acquires right of way over I (rule 10)
  • she is required initially to give S room to keep clear
And typically, in this scenario in the zone, where O intended to duck behind I all along, O gives room by ducking and I keeps clear by standing on.

By now, boats will be inside about 1.5 BL of the mark, with I pretty much on the starboard tack layline.

O now luffs into her tack from starboard to port:

O passes head to wind:
  • O is required to keep clear of I (rule 13);
  • Rule 18 begins to apply  (rule 18.1, same tack in the zone), but only entitles O to mark-room if she is overlapped inside I,
 now claiming an inside overlap

O, tacked and tacked back behind I who is steaming on towards the starboard tack layline:  O is downspeed, falling further behind I, so, unless I hits a brick wall O will be astern of I, not overlapped when O passes head to wind onto port tack.

O, sitting on I's windward hip, might become overlapped inside I when I luffs into her tack from port onto starboard as she reaches the layline, but if I has a, she will simply pinch up a little onto O's line, so that she can tack away clear ahead.

OK, suppose I doesn't tally O on her hip, and rolls into her tack on the starboard tack layline:
  • from the time I's transom-line crosses O's bow, they are overlapped, and I is required to give O mark-room.  The mark-room O is entitled to is room to sail the mark and round it:  it does NOT include room to sail to the starboard tack layline, so there's not really very much room that I is required to give.
  • once I passes head to wind, boats are once again on opposite tacks and rule 18 ceases to apply, but I is required by rule 13 to keep clear, so just like any time a boat tacks from ahead, I needs to be sure that she can reach her close hauled course before O needs to take avoiding action
  • When I reaches her close hauled course, she gains right of way (rule 10), with an obligation initially to give O room to keep clear, but this is still just a boat tacking from ahead and mark-room is not involved.

 on the later tacking I on the basis that the original rule 18 situation no longer applies as one or both boats have tacked. 

18(d) Rules 18.2(b) and (c) cease to apply if the boat entitled to mark-room passes head to wind or leaves the zone. 

Yes, rule 18 switches on and off as boats pass head to wind getting on the same or opposite tacks.  It's actually rule 18.1(a) or (b) that does the switching off, and it's the whole of rule 18

Rule 18.3 would not apply here as no boat completes its tack from PT to STB before entering the zone.

Rule 18.3 no longer has anything to do with 'completing a tack', it depends on a boat passing head to wind in the zone, and the other boat being on starboard tack since entering the zone.

But, right, 18.3 does not apply because no boat entered the zone on starboard

Scenario  2 - Both boats reach the Zone with I to windward of O but with no overlap of O (O is to leeward and ahead).

O is clear ahead and has rights under 18.2(b).

Except in the unusual case where boats are near the bottom boundary of the zone, and I, clear astern, actually reaches the zone before O does, in which case rule 18.2(b) does not apply and mark-room is determined by rule 18.2(a).

However, as soon as she passes head to wind she no longer has any rights

Don't say that.  She has the right to remain silent, she has the right to an attorney, she has the right not to get hit (rule 14), she has the right to be given room to keep clear by a right-of-way boat changing course (rule 16).

I suggest it avoids confusion in thinking and communication if you only use the word 'right' when you mean 'right of way'.  If you want to refer to room or mark-room say 'entitlement'.

So, what O loses on passing head to wind is her entitlement to mark-room.

 as 18.2(d) switches off 18.2(b).

Yes, but again it's probably rule 18.1(a) or (b).

  So it is now port starboard (rule 10)

No, rule 13 kicks in first when she passes head to wind., but same difference.

 and when tacking on to Starboard

Not 'when tacking':  when she reaches her close hauled course on starboard, but again, Yes, rule 15 is going to apply.

  O has to make sure that she observes Rule 15 and gives I Room to keep Clear:

15 ACQUIRING RIGHT OF WAY When a boat acquires right of way, she shall initially give the other boat room to keep clear, unless she acquires right of way because of the other boat’s actions.

I think this one is quite interesting.  As both boats are in the zone, we could assume they are quite close, and any tack from O on to STB would break rule 15.

It'll be rule 13 While Tacking first

However, if far enough ahead, O could argue that it has left enough room for I to duck O after tacking on to STB.

As I've discussed above, an ahead boat with any brains will pinch up to the astern boat's line before she tacks then she'll be able to tack clear, if she just throws into a tack from the leeward berth, she deserves everything she gets.

Rule 18.3 would not apply here as no boat completes its tack from PT to STB before entering the zone.

Scenario  3 - Unconsciously, or consciously, ends up below the lay line and tacks on to STB (passes head to wind) outside the zone.

Here, 18.3 comes into play.  I has little rights.  However, O, I assume, still has to observe rule 15.  I've seen several cases  where O tacks and then tacks to avoid a PT/STB collision.   O then claims an 18.3 violation.  I don't like this approach as O is trying to claim that it is so certain that it completes it's tack outside the zone and I completes it's tack inside the zone.  I would want to pretty sure O could prove this - the most likely event being that both boats are either in or out of the zone.  


18.3 Passing Head to Wind in the Zone If a boat in the zone of a mark to be left to port passes head to wind from port to starboard tack and is then fetching the mark, she shall not cause a boat that has been on starboard tack since entering the zone to sail above close-hauled to avoid contact and she shall give mark-room if that boat becomes overlapped inside her. When this rule applies between boats, rule 18.2 does not apply between them
There is of course a scenario 4 where both boats sail below PT lay line and tac on tot STB outside the zone.  This is then a normal STB lay line rounding and covered well elsewhere.

Scenario 4 - would be where both boats tack onto STB lay line outside the zone.  This is a standard STB lay line and covered elsewhere.

I've seen other discussions of the above 3 scenarios where rule 18 switches off when one boat tacks, but switches back on when the second boat tacks.  I've never understood this logic.  Surely once the lead boat enters the zone we then follow the "thereafter" condition in 18.2(b).  Trying to switch rule 18 on and off while boats are tacking around a mark seems quite haphazard.  

Happy to be critiqued as appropriate - just trying to understand as best I can.

Thanks.



Posted By: redman
Date Posted: 23 Apr 21 at 5:53am
Thanks Brass,

Some excellent insight as always.  Particularly enjoy your comments that every boat still has rights (including the right to get the sod out of my wayWink).

Some thoughts

The more I understand the rules, the simpler they become, and the more I understand why the rules are outlined the way they are.  But what you describe in Scenario 1 sounds like complete and utter anarchy.  Good luck with trying to get any two boats to agree what happened with that.  Even two boats trying their best to do the absolute right thing wouldn't be able to agree on what that looks like.

From memory, the most common incident is when OUTSIDE reaches the STB layline and tacks on to STB.  INSIDE, in order to avoid a collision will tack on to STB as well. OUTSIDE has to initaly give room to INSIDE under rule 15, but can duck under the STB tack INSIDE and under rule 18.2(a) be entitled to room to sail around the mark as long as she does not tack.  Good luck with trying to agree if OUTSIDE has broken rule 15, or INSIDE has broken rule 18.2 (a).  Perhaps INSIDE is OK as long as she does not bare away around WM, and has some protection under 18.2(f), and could argue that she can't luff up away from OUTSIDE as INSIDE's stern swing will impact OUTSIDE.  Perhaps OUTSIDE could argue that INSIDE should have held on port and not tacked on to Starboard (as  STB OUTSIDE was always going to duck PRT INSIDE)

I know we can step through each of these logically, but to me this is a full rainbow away from black and white!!

I am also questioning why 18.2(b) has the term "thereafter".   Thereafter what?  If we're going to allow 18.2 to switch on and off when boats tack, then doesn't this term become meaningless and just add confusion?  In my mind, replacing it with "thereafter give her mark room until the inside boat has rounded/past the mark" would help.  While this understanding may open another can of worms, it would at least force Outside to hold off tacking and stay on Port until Inside tacks.  If there are any boats on STB layline, then OUTSIDE is even more compelled to duck STB to both avoid 18.2(b) infringement on INSIDE and 18.3 infringement on STB.  All the risk would be on INSIDE to avoid 18.3 on STB.

I also don't get why 18.2(d) is there in it's current form.  If 18.2(a) switches off rule 18 in it's entirety when any boats tack, then 18.2(d) only has to worry about a boat leaving the zone.  Unless 18.2(d) is trying to differentiate between passing head to wind and tacking?

Thanks again.  This is all super confusing, but getting to talk/rant through it certainly helps!


-------------
REDMAN


Posted By: jeffers
Date Posted: 23 Apr 21 at 2:37pm
Originally posted by redman

From memory, the most common incident is when OUTSIDE reaches the STB layline and tacks on to STB.  INSIDE, in order to avoid a collision will tack on to STB as well. OUTSIDE has to initaly give room to INSIDE under rule 15, but can duck under the STB tack INSIDE and under rule 18.2(a) be entitled to room to sail around the mark as long as she does not tack.  Good luck with trying to agree if OUTSIDE has broken rule 15, or INSIDE has broken rule 18.2 (a).  

You need to remember just because O gets to the layline first doesn't mean they can automatically tack. If I is close but keeping clear then O will almost certainly break 16.1 when they start to head up:


16.1 When a right-of-way boat changes course, she shall give the other boat room to keep clear.


and potentially 13:


13 WHILE TACKING After a boat passes head to wind, she shall keep clear of other boats until she is on a close-hauled course. During that time rules 10, 11 and 12 do not apply. If two boats are subject to this rule at the same


In most situations I have come across like this O would need to tack then duck to get the inside line to the mark (which may be sub-optimal depending on the next leg) or O would tack with I.

Obviously if there is room for O to tack and fulfil their obligations then they are free to do so but usually when a boat ducks then tacks immediately slightly to windward (to be come I in your scenarios) the separation just isn't there so I holds the tactical high ground despite being the keep clear boat.


-------------
Paul
----------------------
D-Zero GBR 74



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