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Keep Clear boat question

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Sam.Spoons View Drop Down
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Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 06 Sep 18 at 8:30am

Because the definition of windward/leeward (i.e. "A boat’s leeward side is the side that is or, when she is head to wind, was away from the wind. However, when sailing by the lee or directly downwind, her leeward side is the side on which her mainsail lies. The other side is her windward side. When two boats on the same tack overlap, the one on the leeward side of the other is the leeward boat. The other is the windward boat.") mean that neither is to leeward of the other.



Edited by Sam.Spoons - 06 Sep 18 at 8:33am
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 06 Sep 18 at 8:54am
The diagram shows a two sailed boat, where this rarely happens, but it happens all the time in lasers and such like. 

"However, when sailing by the lee or directly downwind, her leeward side is the side on which her mainsail lies. The other side is her windward side."

The definition of windward side (and hence port and starboard) is like this to make port and starboard clear for running boats. It makes sense to have it that way, as rule 10 takes precedence over rule 11. So you want the boats obligations clear in terms of rule 10 even if it means there are occasion when both boats are keep clear in terms of rule 11. 

Probably best to have a situation where both boats are keep clear, rather than mess of trying to decide when boats running dead downwind are changing tack. 
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Post Options Post Options   Quote Eisvogel Quote  Post ReplyReply Direct Link To This Post Posted: 06 Sep 18 at 8:59am
But I'd argue the rule is not fit for purpose if it takes you half an hour to work out who's got priority. And now scale that up to four boats coming downwind on different tacks and trying to see who's got priority over whom and what you need to do...
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 06 Sep 18 at 9:24am
In practice, in the types of boats this occurs, the boat running has a lot of freedom of course and can easily keep clear. 

The other point is, both boats seem to be the keep clear boat, but that definition seems to rely on there being a right of way boat and actually necessitates in in the right of way preamble to section A. So both boats can be defined as right of way and give way. Leaving just rule 14. 

"Keep Clear A boat keeps clear of a right-of-way boat (a) if the right-of-way boat can sail her course with no need to take avoiding action and, (b) when the boats are overlapped, if the right-of-way boat can also change course in both directions without immediately making contact."
Kind of turns in to a chicken and egg situation. If both boats change course to avoid a collision, then have both boats broken rule 11 as the other boat had to change course? 
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Post Options Post Options   Quote Brass Quote  Post ReplyReply Direct Link To This Post Posted: 06 Sep 18 at 9:32am
Thanks Sam.

Blue (B) is sailing by the lee.  The side of B on which her mainsail lies is her port side.  That is her leeward side.  Her windward side is her starboard side (Definitions:  Leeward and Windward:  A boat’s leeward side …, when sailing by the lee or directly downwind ... is the side on which her mainsail lies. The other side is her windward side).

Y is on starboard tack.  B is also on starboard tack (Definitions:  Tack, Starboard or Port A boat is on the tack, starboard or port, corresponding to her windward side).

Next Question:  Is either boat clear astern of the other?  Applying the Definition Clear Astern and Clear Ahead, Overlap, are the boats overlapped?


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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 06 Sep 18 at 9:43am
Originally posted by Brass

  Next Question:  Is either boat clear astern of the other?  Applying the Definition Clear Astern and Clear Ahead, Overlap, are the boats 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."

Neither are clear astern, so they overlap. 


Edited by mozzy - 06 Sep 18 at 9:44am
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Post Options Post Options   Quote Noah Quote  Post ReplyReply Direct Link To This Post Posted: 06 Sep 18 at 9:50am
Bizarrely, according to the definition, they are overlapped, even at position 1, because neither is clear astern. They're both on the same tack so the definition applies. This is all very counter-intuitive, but educational!
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 06 Sep 18 at 10:10am
I think you'll find though its only really an issue if the blue boat is running a long way by the lee. My understanding is that as soon as you have the blue boat a little squarer, or changing course or anything else then step back a few seconds and it all gets simpler. So its a far more unlikely situation than it looks on paper.
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Post Options Post Options   Quote davidyacht Quote  Post ReplyReply Direct Link To This Post Posted: 06 Sep 18 at 11:00am
Originally posted by mozzy

Originally posted by Brass

  Next Question:  Is either boat clear astern of the other?  Applying the Definition Clear Astern and Clear Ahead, Overlap, are the boats 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."

Neither are clear astern, so they overlap. 

Yes, I am with Mozzy on this one ...
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Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 06 Sep 18 at 11:16am
That sounds right to me too, and, as JimC says Y is running so far by the lee that he would struggle to alter course to port (technically to bear away) without precipitating a gybe, planned or otherwise.
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