Forum: Rule 18 and Room at the Mark
Gybing in zone
Casper Lyhne
Nationality: Denmark
0
Hi
Two situations for everybody. One is just the mirror of the other. I wonder how the rules apply. So on the first one green enters the zone well before pink. Both green and pink are sailing their proper course on position 1, that is down-wind VMG sailing.
Is green clear ahead? She entered the zone first, but pink has less distance to sail to the mark. But to me the seem to be overlapped since a perpendicular line off of each transom shows that no boat is clear astern. But under that definition boats quite far behind time-wise could be overlapped. Pink is a little ahead if she sailed her proper course. So here is my interpretation.
When green enters the zone the boats are overlapped, so green is entitled to mark room.
Two situations for everybody. One is just the mirror of the other. I wonder how the rules apply. So on the first one green enters the zone well before pink. Both green and pink are sailing their proper course on position 1, that is down-wind VMG sailing.
Is green clear ahead? She entered the zone first, but pink has less distance to sail to the mark. But to me the seem to be overlapped since a perpendicular line off of each transom shows that no boat is clear astern. But under that definition boats quite far behind time-wise could be overlapped. Pink is a little ahead if she sailed her proper course. So here is my interpretation.
When green enters the zone the boats are overlapped, so green is entitled to mark room.
Green needs to gybe to sail round the mark, and she wants to gybe before the mark to sail her proper couse, which would require more space than mere mark room. But 18.4 also states that it only applies to a ROW boats, so proper course is not relevant to green and she is therefore violating rule 10 by taking more than mark room? Would she be required to sail straight to the mark when entering the zone?
Pink is the ROW boat per rule 10, and at position 2 she is bearing away to let green sail what she thinks is greens proper couse, although green could easily have beared away and sail more slowly to the mark
For the right picture green is the ROW boat, so 18.4 does apply, but it states that "until she gybes she shall sail no farther from
the mark than needed to sail that course" which she is not, and so in the right picture both boats are doing what they are supposed to?
Tbh i would be super stressed out if i was on board the pink boat in position 2 in the right picture. Because I have to somehow anticipate how far green wants to go until she gybes onto her proper course. Especially if green and pink are different types of boats, which would mean different optimal gybe angles. So as pink i would hesitate staying on the outside after it was too late to duck and while green has not started gybing yet.
Pink is the ROW boat per rule 10, and at position 2 she is bearing away to let green sail what she thinks is greens proper couse, although green could easily have beared away and sail more slowly to the mark
For the right picture green is the ROW boat, so 18.4 does apply, but it states that "until she gybes she shall sail no farther from
the mark than needed to sail that course" which she is not, and so in the right picture both boats are doing what they are supposed to?
Tbh i would be super stressed out if i was on board the pink boat in position 2 in the right picture. Because I have to somehow anticipate how far green wants to go until she gybes onto her proper course. Especially if green and pink are different types of boats, which would mean different optimal gybe angles. So as pink i would hesitate staying on the outside after it was too late to duck and while green has not started gybing yet.
Did i get this right?
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No, as you say, simply looking at the definition, the boats are overlapped.
Clear Astern and Clear Ahead; Overlap. One boat is clear astern of another when her hull and equipment in normal position are behind a line abeam from the aftermost point of the other boat’s hull and equipment in normal position. The other boat is clear ahead. They overlap when neither is clear astern.
...They (These terms) apply to boats on opposite tacks only when rule 18 applies between them...
I agree that "proper course" plays no part in the first scenario. At position 2, it looks to me like Pink is bearing away because she needs to give mark-room to Green rather than avoiding contact via Rules 10 &14. In terms of mark-room, we may need more information about conditions such as boat type, sea-state, wind, swell etc. to determine if the mark-room taken by Green falls within the definition of "room".
Room.
The space a boat needs in the existing conditions, including space to comply with her obligations under the rules of Part 2 and rule 31, while maneuvering promptly in a seamanlike way.
Mark-Room
Room for a boat to leave the 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.
Proper Course
...a course a boat would sail to finish as soon as possible...
A agree that the second scenario puts a lot of pressure on Pink. As proper course relies on boat type, weather conditions, tactical execution etc., it would be hard to anticipate/predict Green's actions precisely.
Both Scenarios
Yes. That's exactly how the Definition Clear Astern and Clear Ahead; Overlap works.
Yes.
Here are the relevant parts of the 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.
@1, P overlapped outside, begins to be required to give G mark-room. G's proper course is to sail close to the mark. The mark-room that P was required to give G was the space G needed in the existing conditions to sail promptly to the mark in a seamanlike way. That space was a direct corridor from @1 to a position close to and alongside the mark on the required side (Case 75).
Between @1+delta and @3, G is not sailing within the mark-room to which she is entitled, but no rule says that G is required to sail within that mark-room.
@3+delta G is close to the mark, and is beginning to round the mark as necessary to sail the course. G is now sailing within the mark-room to which she is entitled.
Proper course was relevant to delineating the mark-room to which G was entitled, but she is not entitled to room to sail her proper course.
RRS 10 does no more than require G to keep clear of P. The relevance of mark-room is that if G fails to keep clear but is sailing within the mark-room to which she is entitled, she is exonerated by RRS 43.1(b).
@2 There is 2BL of space between P and the mark and P and the direct corridor to the mark, so P is giving mark-room as required by RRS 18.2(b).
@2, with only 1BL between two assy boats, reaching towards each other, P changes course. It would be reasonable for her to apprehend that if she didn't change course collision would result, so she needed to take avoiding action (Case 50, and thus G breaks RRS 10.
@2 G is not sailing within the mark-room to which she is entitled and is not exonerated for breaking RRS 10 by RRS 43.1(b).
On valid protest penalise G.
No, see above. She is not required to sail within the mark-room to which she is entitled, but if she does not and fails to keep clear she is not exonerated.
I would interpret the diagram as above, that is that P is bearing away to avoid contact with G.
Not relevant.
Yes. P is keeping clear and giving mark-room, G is gybing no farther from the mark than she needs to sail her proper course.
Pretty much.
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On valid protest penalize G.”
——
Left hand scenario: I’m not 100% sure I’d make that determination (but maybe I could be convinced).
First, if you draw a straight line from Pink-1, that path does not leave room for Green to pass between Pink and the mark. Looks to me, Pink’s course alteration to port @2 is a move that Pink would need to do to provide Green mark room. It’s close.
Second, Case 21 tells us:
Looking at the path of green and where she ends up after her gybe, she doesn’t head-up after entering the zone and appears to timed her gybe to put her along the proper-side and close to the mark on the opposite angle without over-standing an inch. The OP facts are that both boats are sailing DW angles appropriate for the boats in the current conditions. Case 21 tells us that we should take into consideration the boat’s design characteristics and sails set. If these are light-hulled boats, Green could come to a complete stop if she doesn’t keep wind in her spin.
In other words, Green’s course does not seem to qualify as a “tactical rounding” as addressed in Case 75 and US 20 based on what I’m seeing. Depending on the characteristics of her hull and sails and conditions, Green’s corridor to the mark could be argued is exactly what she sailed, because she might not be able to “sail to the mark” heading dead down-wind.
There used to be a Case that talked about asym boats and room to gybe and angles … but I can’t put my finger on it.
Anyway .. the combo of both those thoughts would give me pause for DSQ’ing Green based on position 2.
Well put Angelo, that is how i envisioned it. I was envisioning boats like J/80, J/70 or Melges 24's in light air. I made the optimal gybing angles 90 degrees for simplicity, although they would be a bit lower much of the time.
Based on your answers i have revised the left picture into what i think green should have done. So here she gybes while just clear of pink on the inside. Then she sails a bit low straight to the mark. Green is in my opinion therefore sailing in the room she is entitled to, marked in light yellow. Pink then bears away to give green room on the inside. It is a subtle difference from before, but that's where the collisions will happen.
Angelo Guarino Said Created: Today 13:56
Agree. Diagrams only show what the person who drew them thought was important when they drew them.
We might well want more evidence.
Try this diagram showing the mark-room to which P is entitled.
And Case 21 also tells us:
The term ‘existing conditions’ deserves consideration. For example, the inside one of two dinghies approaching a mark on a placid lake in light air will need relatively little space beyond that required for her hull and properly trimmed sails. At the other extreme, when two keel boats, on open water with steep seas, are approaching a mark that is being tossed about widely and unpredictably, the inside boat may need a full hull length of space or even more to ensure safety.
I take this as my starting point: 1 boat length is normally plenty.
Depending on how light the wind was, but is that the action of competent but not expert crew?
Interestingly, see Caspar's post below: he was contemplating sports boats, not skiffs like 49ers or 18 footers, that can stop dead in a gybe.
See Caspar's diagram below.
I used to think that, as Caspar diagrammed, G's direct corridor ran from wherever she engaged with P to the mark. I've changed my position.
Case 75 says
That space was a direct corridor from S1 to a position close to and alongside the mark on the required side.
I don't think that leaves any room to interpret it as anything other than the line from the point where G reaches the zone to the mark.
Doesn't ring a bell, and there's no 'assy' anywhere in the Case Book.
Yes, it's a very subtle change.
Key things are that
I agree that at least from @3, G is sailing within the mark-room to which she is entitled.
The corridor comment, though oft quoted (yours truly guilty), is not in the summary of Case 75, but a statement in the discussion. I think we might consider the context of the statement and the facts surrounding it.
The first words in the Facts are:
The "corridor" quote in context is ..
In case 75's scenario, mark-room IS a direct corridor from the zone to the proper side of the mark, given that these boats were able to "sail directly downwind to a leeward mark". This goes to the sails, conditions, and characteristics of the boats.
As you say .. it's close.
No particular part of a case, such as the headnote or summary, or any other part is more authoritative than any other.
While, if you are arguing by analogy or extension from a case, you might choose to limit your argument by context, when you see the plain words in the case, they are authoritative.
Ang suggested that the 'direct corridor' somehow didn't apply because it only applied when boats were able to "sail directly downwind to a leeward mark". This goes to the sails, conditions, and characteristics of the boats.
Even for performance skiffs like 49ers or 18 footers, it is possible to sail 'directly downwind', even if this is relatively slow or awkward. I can't think of any sort of boat that it is not possible to sail directly downwind.
I don't think that carve-out works.
At the risk of being repetitive, here are the relevant definitions
Mark-Room Room for a boat to leave a mark on the required side. Also,
Room The space a boat needs in the existing conditions, ... while manoeuvring promptly in a seamanlike way.
Ang seems to be grasping after something like 'mark-room is room to sail a boat's proper course to the mark'. I think that's absolutely ruled out.
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I can't readily visualise a situation with problems: The direct corridor seems absolutely consistent to me.
The point in this diagram is that G gybes while she is keeping clear of P, so whether or not she is sailing within the direct corridor is irrelevant.
Going back to the earlier version of the diagram where G gybed later, and P changed course @2, G did not keep clear and whether or not she was sailing within the mark-room to which she was entitled (the corridor) is relevant to whether she is exonerated or not.
Somewhere round about @3, either 3a or 3b, G is rounding or passing the mark, and is sailing within the mark-room to which she is entitled.
Agree.
It is, but not because G is sailing within her mark-room @2.
What I hoped to suggest is that the words "direct corridor" be put into context of the facts of Case 75 and the surrounding paragraph, which I think I did.
The Case-writers summarize the main thrust of the cases for us.
Here is Case 75's:
There is nothing above about defining the bounds of MR in a general sense. Yes .. they use "direct corridor" in the case text while describing the scenario and in making points about how the rules apply in this situation.
In Case 75, to help make the point that Sections A and B apply while rule 18 applies, (in summary) they describe how, as ROW, S is not restricted to her mark-room as long as she complied with 18.4 and 16.1. To do that, Case 75 describes what S's mark-room was in this circumstance so that they can show that S sails outside that mark-room.
What I'm saying is, we know that in the situation of Case 75, Boat S's mark-room was a "direct corridor".
What I am also pointing out is that Case 75 does not make a more general, sweeping statement such as, "A boat's mark-room is a direct corridor that leads directly from where it enters the zone to a position on the proper-side of the mark. Therefore S's mark-room was .... ".
I am noticing (honestly looking at this from a new perspective) that the statement is what S's mark-room was in this circumstance.
I am also wondering (aloud for all to read) if perhaps I may have carried that "direct corridor" idea into situations which were significantly dissimilar from Case 75's facts where it was maybe less applicable.
That is what I'm trying to say.
... and speaking of cases that are specifically focused on defining this space ...
Let's look at Case 118 which actually is focused on interpreting what mark-room is.
Case 118's summary:
Here, Case 118 introduces the term "promptly" directly into the summary of it's key point (and the description). Is an asym boat forced to DDW with a collapsed spin going to sail "... promptly in a seamanlike way to a position close to, and on the required side of, the mark."?
Maybe .. maybe not. It depends.
So, is Case 75's "direct corridor" description of S’s MR in conflict with Case 118's "sail promptly to"?
No, I don't think so when we apply Case 118's description of what ‘room to sail to the mark’ “means” on Case 75's description of what Boat S's mark-room was in Case 75’s specific circumstance. Both boats were sailing directly down wind prior to reaching the zone. Continuing in that direct corridor puts S promptly close to the mark on its proper side.
Now .. back to the OP drawing. Is Green sailing promptly in a seamanlike way to be close to and on the proper side of the mark?
I think she arguably is. Green puts forth the case that sailing the VMG course she did put her in the position close to the mark faster than if she headed lower earlier.
Isn't that “sailing promptly”?