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Oppostie Gybes, leeward Mark

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gordon View Drop Down
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Post Options Post Options   Quote gordon Quote  Post ReplyReply Direct Link To This Post Topic: Oppostie Gybes, leeward Mark
    Posted: 28 Jun 10 at 8:12am
Hull length not boat length - bowsprits, for instance, don't count

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damp_freddie View Drop Down
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Post Options Post Options   Quote damp_freddie Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jun 10 at 10:00pm
That's right, and I was thinking quite wrong: it is 3 of her hull legnths as a circular zone around the mark you must not go outside, and once at the mark you must not sail longer into than you need to.

You could think of it as a truncated circle with the area beyond the gybe or lee mark being cut off due to 18.4 and the definition of "mark room"

Anyway, if you come in on starboard in lightish winds, on the LHS of the Leeward mark, I reckon you can sail a hot angle on STB , gybe to windward of the mark in the 3 boats zone and sail TO the mark on a new reaching angle (while probably taking your kite down)



I consider you have the luxury of doing this because 1. you have the port boats on 10  2. you have overlap on port boats on your beam and behind atleast
3. You then have "mark room" and can gybe by 18.4, taking no more room than required to sail that course
4. You are not sailing beyond your proper course before you are AT the mark  ie at the point you should harden up at a LM.

The crux of the interpretation is in "sail to the mark" ("mark room" definition) and "sail that course" 18.4

For an RS400 to "sail that course" in the abscence of other boats, it would be reasonable to sail hot angles and gybe near the mark to keep her speed: but here we lack " sail her proper course TO the mark" in the definition.

It is therefore vague and I interpret it differently to Gordon.

Whatdyyathink?



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gordon View Drop Down
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Post Options Post Options   Quote gordon Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jun 10 at 8:59am
I believe that the rules are both clearly expressed and well defined... if one reads what is written and takes the trouble to examine the definitions.,

There are a few subtleties - rule 18 does not give an inside boat right of way. Rather, the rule imposes an obligation on the outside boat (which may well be the right of way boat) to allow the inside boat to round the mark in a clearly defined way.

My advice is stop looking for some obscure get out clause that is not in the rules. If you are only entitled to mark room you are ONLY entitled to sail straight to the mark. There is special exception for boats that are designed not to be able to sail straight downwind.

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JimC View Drop Down
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jun 10 at 10:09am
Originally posted by gordon

There is special exception for boats that are designed not to be able to sail straight downwind.

Gordon means NO special exemption of course. Typo I expect.
RS 400s and things sail dead downwind perfectly happily. They just don't do it particularly quickly.
I agree, the meaning of the rules in question is straightforward enough, but if you struggle hard enough you can find a hidden meaning in anything. If you're Dan Brown you can even make a lot of money out of it.

I can remember many years ago, being in a PC that was steadily misleading itself into a complete misinterpretation of a rule. Happily the offending party was much more sensible and retired before we could make complete idiots of ourselves!



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Post Options Post Options   Quote damp_freddie Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jun 10 at 10:12am
Now Gordon- you have hung yourself on "sail straight to the mark" which is not what is stated explicitly or implicitly in the rules:

 we can go back to the more usual situation in a symmetrical fleet, port rounding, all boats on port at the Leeward Mark (LM):

This would mean that a boat clear ahead or with overlap inside,  once in the zone would need to poke its bow right at the LM and not be allowed to go wide in, tight out as is seaman like.

The strict definition is to sail no further than the proper course to round a mark once AT the mark.

I for one would not protest an assy' boat coming in on starboard, with inside overlap, gybing infront of me as long as they don't go outside the 3 boat zone and do not sail further than the mark.
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Post Options Post Options   Quote Sailing4Life Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jun 10 at 10:30am
Relevant parts of Rule 18.2 states:
Giving Mark-Room

(a) When boats are overlapped the outside boat shall give
the inside boat mark-room, unless rule 18.2(b) applies.

(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.

Ok so what else do we need to know, Mark Room:

Room for a boat to sail to the mark, and then room to
sail her proper course while at the mark. However, mark-
room does not include room to tack unless the boat is
overlapped to windward and on the inside of the boat
required to give mark-room.

and the important piece in this is proper course,

A course a boat would sail to finish as soon as possible
in the absence of the other boats referred to in the rule
using the term.

So to help with deciding what a boats proper course is at
a leeward mark where it might gybe the ISAF made 18.4

When an inside overlapped right-of-way boat must gybe at
a mark to sail her proper course, until she gybes she
shall sail no farther from the mark than needed to sail
that course.


The way that I read all of this is, as a assy boat on
stb, coming in hot, I can sail no further from the mark
than to gybe round it and drop, I cannot sail well past
it gybe drop and round once in the zone I must sail the
fastest course (one I would sail to get to finish
quickest)
Rs600 + many others
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gordon View Drop Down
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Post Options Post Options   Quote gordon Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jun 10 at 10:35am
There is an essential difference between the entitlement of a keep clear boat with mark room and a ROW boat with mark room

A keep clear boat entitled to mark room is most definetely NOT allowed to as so-called tactical rounding. Mark-room entitles a boat for room (as defined in the rules) to sail to the mark. This gives that boat a narrow straight corridor from the point of entry to the zone to a position alongside the mark at which it is seamanlike to change course to round the mark. The concept of proper course does not apply UNTIL the boat is at the mark.

It is important to note that the definition of proper course is not the fastest course from the start to the finish, but the fastest course from where the boat is at any given moment to the finish. When a keep-clear boat is entitled to mark room she is NOT entitled to sail her proper course until she is at the mark.

The situation is very different for a right of way boat entitled to mark room - they are allowed to sail their proper course to the mark, subject to the limits imposed by rules 15, 16, 17 and 18.4. A ROW boat may sail a tactical rounding.


a boat can lose ROW during a rounding (by gybing on to port,overlapped to windward, for instance), and is then only entitled to mark room.

Can't see how I can make this any clearer

Gordon

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JimC View Drop Down
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jun 10 at 11:09am
Originally posted by damp_freddie

This would mean that a boat clear ahead or with overlap inside,  once in the zone would need to poke its bow right at the LM and not be allowed to go wide in, tight out as is seaman like.


No, No, No. You're confusing yourself again... The crucial point you seem to be struggling with is the difference between a boat with right of way and a boat which is simply entitled to room.

If you have right of way you can pretty much sail where you like given certain limitations, principly those to boats that are entitled to room.

If you are entitled to room, but are otherwise the give way boat then all you can do is sail to whatever place you are entitled to room to get to. Room is not the same as right of way.

A boat clear ahead almost certainly has right of way. An inside overlap boat may or may not have right of way, depending on circumstances. If its on port and the other boat is on starboard the inside boat does not have right of way for instance, but if the inside boat is on starboard and the outside boat is on port then the inside boat has right of way.
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Post Options Post Options   Quote asterix Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jun 10 at 11:28am

I agree with the good advice given by Gordon above.  I also think damp_freddie is seeking to sail in a way that would at best only give a very marginal benefit but which in practice might not actually be beneficial or successful on the water. 

Having said that, I would make an observation that the current rules do not describe sufficiently well what is meant by 'sail to the mark' - as is evidenced by this debate, by the apparent need to clarify the requirement to sail 'straight' to the mark 'in a narrow corridor', and by other similar conversations I have heard at my club.

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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jun 10 at 11:48am
Grief boys: its just english.
Sail to the mark, not via somewhere else.
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