The Racing Rules of Sailing

Overlap or not?

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Vladimir Leonov
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Just a simple question. Are Yellow and Green overlapped through Blue between them?

Situation 1
Situation 2
Created: 20-May-10 19:56

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Mark Townsend
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In situation 1 and situation 2 as all boats are on the same tack we can use the first three sentences of the definition Clear Astern and Clear Ahead; Overlap to determine if they are overlapped.   
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.
There is a second test in the fourth sentence of the definition, which will also need to be applied.
However, they also overlap when a boat between them overlaps both.

Situation 1 & 2
  1. Yellow, Blue and Green are all on the same tack 
  2. Yellow is not clear astern of Blue, and Blue is not clear astern of Yellow. So as neither is clear astern of the other, and they are on the same rack, Yellow and Blue are overlapped.
  3. Blue is not clear astern of Green, and Green is not clear astern of Blue. So as neither is clear astern of the other, and they are on the same rack, Blue and Green are overlapped.
  4. Yellow is not clear astern of Green, but Green is clear astern of Yellow. Under the first test Yellow and Green are not overlapped.
Situation 1 (2nd Test)
  1.  Blue overlaps both Yellow and Green, and Blue is between Yellow and Green so Yellow and Green are overlapped.
Situation 2 (2nd Test)
  1. Blue is not between Yellow and Green so Yellow is clear ahead of Green.
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.  These terms always apply to boats on the same tack. They apply to boats on opposite tacks only when rule 18 applies between them or when both boats are sailing more than ninety degrees from the true wind. 
Created: 20-May-10 20:40
Eric Rimkus
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They are all on the same tack. 
Blue and Yellow are overlapped
Blue and Green are overlapped
Is Blue between Yellow and Green?
Created: 20-May-10 20:45
John Ball
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I disagree with Rick. Refer to the sentence prior to the one he cites from the definition for clear ahead/clear astern/overlap which says "These terms always apply to boats on the same tack". Yellow, Blue and Green are all on the same tack, so the term may apply to them.
So Yellow and Blue are overlapped and Blue and Green are overlapped. So Yellow and Green are overlapped as Blue is between them, however briefly, and with no other factors present, it would appear to have little significance. However if Yellow was entering the zone of a mark while Blue was exiting the mark, it could give Green mark room, even if the overlap is subsequently broken. 

John
 
Created: 20-May-10 20:48
Vladimir Leonov
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Yes, Blue and Yellow are overlapped
Yes, Blue and Green are overlapped
That is pretty clear... But what about Yellow and Green? Is Blue "between" them to comply with the definition "Overlap" or not? 
Created: 20-May-10 20:59
Mark Townsend
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They also overlap when a boat between them overlaps both. In situation 1 Blue is in the space separating Yellow and Green, so is between them. In situation 2 Blue is not in the space separating Yellow and Green, so is not between them, If you can draw a line from Yellow to Green and it touches Blue, then Blue is between them, otherwise she is not.

Created: 20-May-10 21:38
Dušan Vanický
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Mark, according to your bow to bow line ( which according to mee is irrelevant), the next yellow and green would be not overlapped.
Created: 20-May-10 23:24
Thomas Hampton
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I would add a stern-to-stern line to Mark Townsend’s Diagram with the bow-to-bow line, thus forming a box. If blue is inside the box, she would appear to be between yellow and green and therefore yellow and green would be overlapped. If blue’s outside the box, then no overlap.
Created: 20-May-10 23:41
Mark Townsend
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The line can go from any point on Yellow to any point on Green. I drew one between the bows as that demonstrated that Blue was between Yellow and Green.

In the diagram below I drew a line between the boats bows and another between their sterns, any boat that touches the blue shaded area is between the boats. Or... the way I remember it is, if you can draw a line from Yellow to Green and it touches Blue, then Blue is between them, otherwise she is not.







Created: 20-May-11 00:20
Martin Rheaume
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Situation 1: In the definition of Leeward/Windward, it says "when two boats on the same tack overlap,  the one of the leeward side of the other is the Leeward boat. The other is the Windward boat.   Blue is on Yellow's leeward side and Yellow is on Blue's leeward side so which boat is the windward/leeward boat ?  
Created: 20-May-11 00:52
Philip Hubbell
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We have enough difficulty determining when (Yellow) is at three boat lengths.
The two seconds' transience of (Blue) overlapping (Yellow and Green) sailing in the opposite direction cannot reasonably be found as Fact in a hearing unless both agree to the timing.
Edit:
 Therefore, per 18.2.e, it shall be presumed that (Green) did not establish an overlap.
Created: 20-May-11 01:10
Dušan Vanický
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Philip, you do not play Vladimir's question. :-) 
Mark, what about the "space" "between Y and G" as per the pic below?
Something similar (with an unclear convention about parts of the geometric plane) was at the table with the starting line (and its extensions.)
Created: 20-May-11 05:08
Ric Morris
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With conjunction [^], disjunction [v], implication [<-], and compliment [!] and clauses highlighted:

They apply to boats [<-] (on opposite tacks) only [^] (when rule 18 applies between them) or [v] (when both boats are sailing more than ninety degrees from the true wind).

The common order of application is compliment, conjunction, disjunction, implication; so this sentence is equivalent too:

To be overlapped boats, either:
1) Rule 18 applies between them and they are on opposite tacks
2) They are both sailing more than ninety degrees from the true wind.

They are not overlapped as:
1) None of them is in the zone,
2) Blue is not 90 degrees from the true wind

Created: 20-May-11 06:47
Ric Morris
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(yes I did miss the sentence before!)
Created: 20-May-11 10:16
Mark Townsend
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Duscan, Your diagram shows the space between the tracks of Yellow and Blue, not the space between the boats.

Created: 20-May-11 16:26
Dušan Vanický
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Mark,
I slightly changed the diagram. 
Can you put the shaded space between Y and G?
If B is in that space, is it between Y and G?
I am not sure and so I support the doubt of Vladimir, who came with an interesting moment.
 
Created: 20-May-11 21:08
P
Uros Zvan
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Dušan, boats in situation 2 are forming triangle. Just forget that they are moving. Is it blue in between yellow and green? No.
Is it boy in green shirt in between boys with red and grey shirt? No.
Created: 20-May-11 21:39
P
John Allan
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Philip Hubbell
said Created: Today 01:10
We have enough difficulty determining when (Yellow) is at three boat lengths.
The two seconds' transience of (Blue) overlapping (Yellow and Green) sailing in the opposite direction cannot reasonably be found as Fact in a hearing unless both agree to the timing.
Therefore, per 18.2.e, it shall be presumed that (Green) did not establish an overlap.
That looks like very good logic to me.
Created: 20-May-12 01:39
Christian Hartmann
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i go with Ric, so none of the boats overlap with any other. (accoring to the def.: when both boats are on a course with more than 90 degrees to true wind)
Created: 20-May-13 12:27
Mark Townsend
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Christian, The sixth sentence, which you are quoting, is only relevant to boats on opposite tacks. Yellow, Blue and Green are all on the same tack. The first four sentences always apply when boats are on the same tack.

Read the entire definition of Clear Astern and Clear Ahead; Overlap, which is below with sentences numbered.
  1. 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.
  2. The other boat is clear ahead.
  3. They overlap when neither is clear astern.
  4. However, they also overlap when a boat between them overlaps both.
  5. These terms always apply to boats on the same tack.
  6. They apply to boats on opposite tacks only when rule 18 applies between them or when both boats are sailing more than ninety degrees from the true wind.   

Vladimir's question was simple "Are Yellow and Green overlapped through Blue between them?" and there were two situations in the diagram.  

In situation 1 and situation 2 all boats are on the same tack, so we can use the tests in first four sentences of the definition Clear Astern and Clear Ahead; Overlap to determine if they are overlapped. First test: 
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.
There is a second test in the fourth sentence of the definition, which will also need to be applied.
However, they also overlap when a boat between them overlaps both.

Situation 1 & 2 (1st Test)
  1. Yellow, Blue and Green are all on the same tack.  
  2. Yellow is not clear astern of Blue, and Blue is not clear astern of Yellow. So as neither is clear astern of the other, and they are on the same tack, Yellow and Blue are overlapped.
  3. Blue is not clear astern of Green, and Green is not clear astern of Blue. So as neither is clear astern of the other, and they are on the same tack, Blue and Green are overlapped.
  4. Yellow is not clear astern of Green, but Green is clear astern of Yellow. Under the first test Yellow and Green are not overlapped.
Situation 1 (2nd Test)
  1.  Blue overlaps both Yellow and Green, and Blue is between Yellow and Green so Yellow and Green are overlapped.
Situation 2 (2nd Test)
  1. Blue is not between Yellow and Green so Yellow is clear ahead of Green.



DEFINITION - 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. However, they also overlap when a boat between them overlaps both. These terms always apply to boats on the same tack. They apply to boats on opposite tacks only when rule 18 applies between them or when both boats are sailing more than ninety degrees from the true wind. 
Created: 20-May-13 15:34
Christian Hartmann
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@Mark,  reading the definitions with your comment in mind ... i go with your interpretation.  maybe i was on a wrong path with the german(!) definition :(  this one id defined in counterwise words and seems to be in conficht with the english wording.  glad to be race officer only ;)
Created: 20-May-13 16:53
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