1(a) Ben says Blue's track is her proper course.  She gybes no farther from the mark than needed to sail that course.  If RRS 18.4 applies Blue does not break that rule.  Blue is entitled to sail the course illustrated.

1(b) Sailing a course so as to finish as quickly as possible is self evidently tactically desirable, but how is that characterisation helpful in applying any of the RRS in this scenario? 

1(c)  When Blue leaves the mark astern she is no longer sailing within the mark-room she is, or was entitled to, and she has been given room to sail within that mark-room, so RRS 18 no longer applies, so even if Blue had stood on to position Green 4, she would not break RRS 18.4, because RRS 18 ceased to apply when Blue left the mark astern.

I'm guessing that Ben is leading up to a mirror image scenario with Cyan a little more advanced and Blue not keeping clear.

John,

Perfect - thanks for the reply.  As I said, mainly rhetorical at this stage...I agree with most of what you've said.  (The reason for 1b is just to set the terminology straight - relative to a more conventional use of term 'tactical rounding' - wide in>tight out.) (Just to be clear, I don't want to ignite the debate of when mark-room is done here.  I'm more interested in Port's obligations under R10.)

I'll not hang around then...  straight to Q2.  (Not the mirror image, but alluding a concern I have as to how 18.4 is practically coached and how the rule is taught.).

OK - So some may say R18.4 does not apply according to the R18.1(b).  Whether right or wrong, we're back to the basic RoW rules.  (Rule 10).
------------------------------
Question 2.

Starboard sails above her proper course and is found to have broken R18.4.

There is a collision between Port and Starboard which causes damage.

2a)  Does Starboard break rule 18.4?  Let's not get hung up on this.

2b) Is there any exoneration for Port?

(No other boats affecting these two.)

2(a)  already answered:  somehow or other now Green in this diagram has broken RRS 18.4

Magenta breaks RRS 10, and could reasonably have avoided contact by keeping clear, so also breaks RRS 14.

I think that even if Green was bearing away into her gybe when contact occurred, she was giving Magenta room to keep clear and not breaking RRS 16.1.  Green was turning away from Magenta when contact occurred:  it was not reasonably possible for Green to avoid contact and Green did not break RRS 14.

2(b)  Exoneration:

Green

Green breaking RRS 18.4 was neither compelled by (RRS 43.1(a)), nor as a consequence of  (RRS 43.1(b)) Magenta breaking either RRS 10 or RRS 14.  Green is not exonerated for breaking RRS 18.4.

Magenta 

RRS 43.1(a)  Was Magenta compelled to break RRS 10 and 14 by Green breaking RRS 18.4? No:  Magenta could readily have changed course in either direction and kept clear.   Magenta is not exonerated by  RRS 43.1(a). 

RRS 43.1(b) Was Magenta sailing within the room or mark-room to which she was entitled?  No:  Magenta was not entitled to any room or mark-room.  Magenta is not exonerated for breaking RRS 10  by  RRS 43.1(b).

RRS 43.1(c). Was Magenta a right of way boat or entitled to room or mark-room?  No.  Magenta would not be exonerated for breaking RRS 14 by  RRS 43.1(c), even if there had been no injury or damage.


Ben, are you feeling around for a situation where a boat is sailing outside the room or mark-room to which she is entitled, but still bound by some part (RRS 18.4) of RRS 18?

Or, conversely, are you trying for a proposition that once a boat is sailing outside the mark-room to which she is entitled, RRS 18 necessarily does not apply?

John,

Again, thanks for engaging here.  I think we have covered what I need to present the problem I have.

(Apologise for the colour changes - I simply overlayed a number of boats over each other to make each of the different scenarios.)

Right, back to the point.

This all comes from a real case, where Port felt aggrieved at the end of a hearing, claiming that Stbd stood-on dangerously.  This got me thinking.

My serious concern is that Port boats are being coached wrongly and dangerously.

Again, John I agree - no exoneration for Stbd (if she did break 18.4), and no exoneration for Port (rule 10).

The issue..

I think that practically, coaches are wrongly training that Port can expect Starboard will round the mark (at least on her proper course, but worse/incorrectly,  immediately - a seamanlike rounding.)

This expectation leads to dangerous situations where Port does not prepare for a Stbd boat who may have a wider idea of what her PC is or may overstand on starboard accidentally or deliberately in order to force Port to gybe away.

-------------------

Q3 - Can Port sail with the expectation that a boat will not break a rule (18.4)?  Can Port use it as a defence when she breaks Rule 10?

Q4 (Extra bonus) - If John's assertion that R18 is off as soon as starboard leaves the mark astern so Rule 18.4 does not limit Stbd, can Stbd then stand-on on stbd with no limit of 18.4 to force Port to tack?

--------------------

In short, I think that Port boats must be coached as if they have 'no rights' and to sail as if there wasn't a mark there at all.  That's the safest.  Then if she thinks that Stbd broke 18.4, she could protest.

Unfortunately, I think what is actually happening in training is the other way round.

Ports are being trained that Stbd must/will round pretty tight - the fastest she can.  Port intimidates/bullies Stbd (at the time or afterwards) to round tighter, and complains when Stbd doesn't.

(This actually doesn't matter whether you think that mark-room was given and R18 was on or off.  Either way, Rule 10 is on and Port should treat this like any Rule 10 situation.  John, if no 18.4 then technically Stbd is not limited and can remain on starboard, no? - Hmm...)

Does any of this make sense or have I confused it further.

Ben, that's interesting.  Am I interpreting this correctly?  It seems to boil down to a possible disconnect between a boat's obligations under 18.4 and MR's "leave it astern".  

Interestingly ... 18.4 makes no actual reference to mark room.   

Can't we make the case that it's actually misplaced under 18?  Is it not really an independent limitation on a ROW boat independent of MR?

Wow ... Would 18.4 be better placed in Part 2 Section B or a separate rule under Section C?  (Seems to be more akin to Rule 17 as a specific-case course limit on a ROW boat). 

In the last image posted:
between 2 and 3 Green is sailing to the mark when her proper course is to round it.
When Green reaches the zone she is overlapped inside Purple and is entitled to mark room under 18.2(a)(1).
At the mark Green takes no action to round the mark on the required side. Green is sailing outside the mark-room to which she is entitled, so she cannot be exonerated under 43.1(b).
Green is now sailing parallel to the finish line, it could be argued that she is not sailing towards the finish line. Green would have difficulty in convincing a PC that she is sailing in a manner so as to sail the course as quickly as possible the course. 
In any case, Green is on starboard. Purple on port is required to keep clear, which she fails to do and breaks rule 10.
In order to be exonerated Purple would have to demonstrate that:
i) Green broke 18.4
ii) Purple was compelled by Green's breach of rule 18.4 to break rule 10. Good luck with that.

The best probable outcome for Purple is that both boats get disqualified.

Benjamin. Am interested to know which diagram prog you are using.

Well, I'll be honest and say that my main point with this thread is my suspicion that 18.4 is being coached wrong and potentially dangerously.

However, yes Ang.  I originally set out to point out that 18.4 doesn't have anything to do with mark-room.  That teaching the port boats that they must give 'room' or 'mark-room' to starboard is not the whole truth and dangerous.  It puts an incorrect perception into port's mind of their obligation.

No.  Simply, Port must primarily keep clear under rule 10. End of.

(The mark room of 18.2 is essentially irrelevant and just confuses the matter.)

I wanted to stress that perhaps this is what we should be focusing on as rules 'gurus' when we teach rule 18.4 practically.  It would be safer if all Port boats were ready to keep clear of Starboard no matter what track Starboard sailed, right?

And then John reminded me of the rather curious connection with mark-room via 18.1(b).  18.4 is linked to mark-room. Sigh!

It should be a limitation to RoW regardless of mark-room, but actually turns out expiring per the new definition when the mark is astern - now we have added a new confusion to the real life application of the rule.  It solidifies my case that there is something dangerous about 18.4.
-------------
So to bring us back on track, I ask, is 18.4 being coached correctly and safely?  What is actually happening in the real-life coaching world?

My suspicion is that youth sailors are being taught that 18.4 means that Starboard is only entitled to mark-room and will have to gybe. Kind of true, but I fear he basic requirement for port to keep clear is being brushed over or forgotten.

In some cases, the coaches are interpreting that phrase 'proper course' as meaning, "Sail to the finish as soon as she can" e.g. "GYBE IMMEDIATELY".  If this is what is being taught, it is incredibly dangerous, since Port will sail with those expectations, rather than with the caution and keep clear mindset required.

Accidents will happen.

So, boiling it down as Ang says, perhaps 18.4 shouldn't be linked to mark-room (especially with the new definition).  Perhaps it should be of the same status as say, 'Rule 17'. A limitation to RoW.  That's what it is, right?

Or perhaps 18.4 causes more problems than it solves and it just needs to be deleted all together.  

Robin Meads,

This is a tool called 'Boats'.

https://sourceforge.net/projects/boats/

Hope that helps.

Thanks Benjamin

Ben re: "In some cases, the coaches are interpreting that phrase 'proper course' as meaning, "Sail to the finish as soon as she can""

It's "farther .... than needed to sail the course" in 18.4, not "proper course".   So, yes, if they are teaching based on a "proper course" concept, they are clearly coaching incorrectly.

In your OP drawing, given the shown wind direction, location of the FL and the demonstrated gybe angles, there is no "need" to sail further from the mark than would be "needed" to complete a seamanlike gybe-rounding. 

That said, a seamanlike gybe-rounding might involve sailing the stern past the mark (by a competent but not expert crew), so our conundrum continues somewhat. 

In a past thread, I argued that "left astern" should be interpreted to include "clearing" the mark as well (as we do when we determine when a boat is no longer "racing") which would extend the time to include the idea of when a boat's course is no longer being "influenced" by the mark.  Doing so would then exclude a moment that the mark is astern just prior to a boat turning, thus returning the mark forward of her stern perpendicular. 

All that said ... yea ... I think it might be clearer to have 18.4 separate. 

Geometrically, a gybe immediately at the mark is the shortest distance, however a smoother turn is quicker overall. It depends greatly on the kind of boat of course. 

But as I keep saying, this thread is not so much about 'when Starboard' must gybe, but more about Port's underlying obligation to keep clear above all else. 

After all, if a bunch of Internet rules nerds (us) can't work out when Starboard must gybe from the comfort of our our armchairs, what chance do the sailors have on the water!

So I reiterate, focus on the Rule 10, not the Rule 18.2.

Ben re: "Geometrically, a gybe immediately at the mark is the shortest distance, however a smoother turn is quicker overall. It depends greatly on the kind of boat of course.

My point is that concepts around "quicker over all" have no part to play in 18.4.  It's only what is "needed to sail the course" (not quicker/desirable/preferable).
(above is incorrect .. I inadvertently was replacing "the course" for "that course", which makes all the difference)

Also, interestingly as Rob O points out regarding RRS 17, it appears a ROW boat can break RRS 18.4 even if the KC boat's course is not impacted in any way. 

Huh ... that really highlights the similarities between 17 and 18.4 and maybe is another way to talk about your point, Ben. 

We often tell sailors that it's important to understand that RRS 17 does not convey "room" to the windward, KC boat.  Therefore there is no exoneration for breaking RRS 11 for windward, even if leeward breaks 17 (assuming 15 or 16.1 not broken).  So, if you are windward under 17, KC of leeward and protest if you think they are sailing too high. 

Likewise (your point Ben) is that 18.4 does not convey "room" to the KC boat.  Therefore, likewise, the KC boat is not exonerated for breaking RRS 10 or 11, even if the ROW boat breaks 18.4. They must prioritize keeping clear first and then protest. 

PS: I feel like I'm talking myself into the POV that 18.4 should be part of 17  (a new 17.2) and 17's title reworded "Course limits on ROW boats"

How can 18.4 even exist where it is, since, in our example:

18.1.(a): "Rule 18 applies between boats when they are required to leave a mark on the same side" 
in the diagram S no longer needs to leave that mark on any side, 
and

18.1.a (3) [18 does not apply] "between a boat approaching a mark and one leaving it"

Philip,

The diagram depicts the last reaching finish leg leg of a course like this.

https://assets.rya.org.uk/assetbank-rya-assets/action/directLinkImage?assetId=50311

I'm pretty sure 18.4 applies.

I’m with Philip - green is leaving the mark.  

To Angelo’s ‘quicker overall has no part to play’….surely the reference to proper course in 18.4 does bring ‘quicker overall’ into play?

Fair enough.

As I said, whether 18. 4 is on or off doesn't wally matter. Point is that Port better be ready to keep clear! 

Matt and Ben, you're correct.  I spaced-out on the "that" in "that course". 

It's not "further from the mark than needed to sail the course." .. .it's "further from the mark than needed to sail that course."

I had thought they changed it from "that" to "the" in 2025.  Somehow my mind was playing tricks on me and replacing "the" for "that" each time I read it.

(you can see that I was typing "the" in my replies .. yuk!)

"That course" refers back to the previous reference of "proper course" earlier RRS 18.4.  So yes .. my previous comments to Ben were incorrect.

Thanks!

After passing the mark Green is sailing a course parallel to the finish line, while Purple is sailing a course perpendicular to the finish line. Not sure how Green is sailing the course as quickly as possible. Green may have broken 18.4 by not gybing at the mark. Green would have to persuade the PC that a finish at the starboard end of the line was advantageous so her proper course was to stand on.
I am not convinced that if the PC decided that Green had broken 18.4 they would conclude that this breach had compelled Purple to break RRS 10 and give exoneration under 43.1(a)
Green has been given room to sail to the mark. She has been given room to pass the mark and to leave it astern. According to the definition, mark-room has been given. RRS18 no longer applies when contact occurs.

I think Gordon Davies' response was more to the point for Q2.
1. A boat is not obliged to anticipate that another boat will break a rule (Case 3)
2. 18.1 (a) states that it applies between boats when they are required to leave a mark on the same side and ... 
3. Green standing on unreasonably / not on proper course cannot be said to have left the mark astern for the purposes of 18.4, as she has not taken the mark room to which she is entitled, as she has not rounded the mark.
4. The definition mark room states (b) to round or pass the mark on the required side, AND (c) to leave it astern, so the leaving it astern cannot take place until it has been rounded/passed. 
5. As Green is on stbd she does have the right to take the rounding wide, however this has to be proved as being her proper course. See also Case 75 (if that will be in the new case book)
6. On the diagram provided, I would find that:
a) Mark room has not been give at point 4 as Green has not exercised Def (c) due to Def (b) not having taken place
b) 18 has not switched off, as Green has not rounded the mark and then left it astern at point 4 (i.e same reason as a))
c) Green in breach of 18.4 as by sailing further from the mark than needed as she did, she is not sailing her proper course 
d) Purple not obliged to anticipate that Green would do that.
e) Purple exonerated for breach of 18.2(a)(1), possibly also for 10 & 14 under 43.1(a)
f) Green not exonerated 43.1(b)

Robin,

Can I drill into this idea that Port does not have to anticipate that starboard will break a rule...?

It is a well agreed principal that a boat does not have to anticipate another will break a rule.  Stbd should gybe at or before her PC.

I'm not sure I agree that this can be used as a defence to gain exoneration under 43.1(a) in this case though.

No matter how Starboard sails, Port (Magenta) still needs to anticipate her obligations under Rule 10.  Since that 'keep clear' obligation is  on here, Port can't really claim that  she was compelled to break R10 because Stbd broke 18.4.

This is my basic point to all this - Rule 10 ROW is still on.  Everyone forgets it, yet it is the key to safety.

So, Port doesn't get exonerated in my opinion even if Stbd did sail further than allowed.

I DSQ both boats in Q2.

-----------------

I think Robin has done exactly what I suspect coaches are doing... focused on the concepts of room, mark-room and proper course, and ignored R10 and Port's obligation to keep clear no matter what Stbd does, which is the one which will prevent damage and injury.

Do we really want boats making that call (and sailing to that expectation) on the water?  Imagine 2 skiffs on collision course with closing speed of 20kts, and Port helm asking her own crew, "Do you think she will gybe or won't she?  Let's sail as if she will gybe at exactly 1.2 boat lengths from the mark and hope for the best!"

Yeah...nah.

Ben re: " I DSQ both boats in Q2. "

Agree .. just as in RRS 17, RRS 18.4 does not convey room to the keep-clear boat.  Assuming that RRS 16.1 or RRS 15 does not apply (which would convey room to the keep-clear boat) the KC boat has no access to exoneration under 43.1(b) or 43.1(c) for breaking RRS 10 or 11.  Likewise, RRS 43.1(a) does not apply to the keep-clear boat as under both RRS 10 (as shown in OP) or RRS 11 (not shown), the keep clear boat's obligations  to keep clear under those rules are not diminished.

Robin -
Regarding your point 4, there is nothing in the definition of mark-room that requires that (a), (b), and (c) happen in that order or that one must happen before the other can take place.

I am feeling playful today.
In the original scenario does 18.4 ever apply?
Mark room stops when the mark is astern.  Does here 18 get switched off before 18.4 can apply?
THis has wider implications. At mark 3 of the regular team race 18.4 does not apply, but starboard often passes the mark leaving is astern, gybes inside the zone and proceeds on port to mark 4.
She was previously considered to have mark room so protected from approaching starboard boats.
Yes she did have restrictions, she could no longer sail to the mark (her proper course being below) and if she luffed she was not protected from 16.1 as she was then outside her mark room.
Do we now say 18 is off for the starboard boat when the mark is astern, if so no protection from the starboard boats, we may have a new game!

Robin wrote:
 The definition mark room states (b) to round or pass the mark on the required side, AND (c) to leave it astern, so the leaving it astern cannot take place until it has been rounded/passed. 

Green chose not to change course at the mark. But she has clearly passed the mark and left it astern. So she has been given mark-room. When there is contact Rule 18 no longer applies. Mark-room does not require a boat to change course at the mark.
The PC may decide that Green breaks RRS 18.4 at the mark by not changing course. That would depend on the angles the type of boat sails, the exact wind direction and the position of the finishing line.

John  I would argue that sailing to the mark precedes rounding or passing  the mark, which then precedes  leaving it astern

Gordon,
In most cases that is the natural progression.  In places like San Francisco, where there is a lot of current, you can leave the mark astern and then pass it.  18 no longer applies when each of the things has been done, regardless of the order.  If the rule writers meant to imply an order they would have used 'then' instead of 'and'.

Or alternatively, until you have passed the mark 'the leaving it astern' does not apply
I understand that there is some debate about the exact meaning of the definition and look forward to reading the Q&A.

1. Ben, if the Sailing Instructions maintain the leeward marks as gate marks throughout, then, RRS18.4 does not apply and Magenta has to give way to Green under RRS10. Period.
2. We both have done island races with keelboats before. If the mark is an island to be rounded before the finish, Green may have a deeper keel and is complying with RRS18.4 by carrying out a wider seamanlike rounding, sailing no farther than needed to sail the course to the finish line without running aground. Magenta may have a shorter keel (maybe a Cat?) and can sail a tighter course around the island towards the finish line. Magenta had better keep clear of Green (emphasising the need to coach boats their obligations as you rightly pointed out) unless she can prove in the hearing  that Green broke RRS18.4, in which case, Magenta has to read the above discussions to prepare her case.

Hi Leonard,

1.  Yes - at a gate 18.4 is not applicable, so boat's naturally sail to Rule 10 - at least I hope so.  In my example, 2P was not meant to be a gate.

2.  Your illustration of the case with the mixed fleet and island surrounded by varying depths really helps give a practical explanation of the rules.  As Brian would say.. 'The rules in practice'.

As you say, Magenta had better read the discussion.  On the water she needs to be prepared for any track by Green (including a late gybe or even no gybe.)  Magenta to keep clear.

Thanks for that.

Re your last sentence...

If Magenta can prove Green broke 18.4, there is still the interesting question whether she can use this as her own defence for her R10 breach?  Did Green's breach compel Magenta to fail to keep clear?

I don't think so.  I don't think that proof helps Magenta, except that Green get's pinged.

Gordon, I see the logic of your argument, but surely passing or rounding a mark governs the actions required to make it either a passing or rounding mark.. For Green the mark is a rounding mark, otherwise she cannot sail to the finishing line. If she continues on a course without rounding it & delays attaining her proper course for the next leg, until she does so she has not done both Def (b) & (c), because she is obliged to round the mark at some point, not pass it,  therefore she remains liable under 18.4. If you are correct then any boat that leaves the mark astern at any point of rounding a mark without completing a rounding (trouble with spinny perhaps) immediately loses mark room & cannot be penalized under 18.4, which only leads to the conclusion that the Def & 18 are poorly written.

How do you immediately loose mark room without tacking or sailing out of the zone.

The new loss can be the mark left astern, this is proving to be such a loose term, and a potential problem.

See my comment on the affect on team racing above.

The rule now seems a mess.

Robin,
What rule, other than 18.4, requires a boat to change course at a mark? A rounding mark is a mark in which the string, when drawn taut, touches the mark. However, that does not define the course that a boat need sail. 
In this case, assuming that before reaching the mark, Green is sailing at her 'hot' angle. Depending on where the finish line is exactly, depending on the bias on the finish line, on expected wind changes.... Green may well believe that the quickest way to sail the course is to stand on.
So, at position 3.5, Green has been given room to sail to the mark, room to pass or round the mark and room to leave it astern. Mark-room has been given, so RRS 18 ceases to apply.
To penalise Green for a breach of RRS 18.4, the PC must establish that while RRS18 applies (from when Green enters the zone until mark-room has been given) that the quickest route for Green to sail the course was to gybe.