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Oppostie Gybes, leeward Mark

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Garry View Drop Down
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Post Options Post Options   Quote Garry Quote  Post ReplyReply Direct Link To This Post Topic: Oppostie Gybes, leeward Mark
    Posted: 18 Jun 10 at 1:09pm

Surely by the time you reach 3 boat lengths its less
about hot angles and more can you sail low enough to
execute a fast drop?


garry



Thinking triangles and sausages here.

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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: 18 Jun 10 at 10:58am
Yes, a gybe could be necessary, but if boat entitled to mark room is not right of way boat then she is not entitled to sail "hot angles" but only to sail directly to the mark (even if this is dead downwind).

If she does anything else she must keep clear.

That is a fine distinction which many sailors have difficulty appreciating.

Gordon
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Post Options Post Options   Quote damp_freddie Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jun 10 at 9:05am
it could reasonably include a gybe in the situation discussed though.


Yes jeffers, it seems a bit of flock mentality going left!

Once in an RS400 club race I had spinnaker issues and while they were sorted ran DDW. Quite quickly, and the VMG was amazing.

I then got the knickers up and took the whole fleet on starboard at the (two boat) zone.

Pepsi and Phoenix used to sail well longer than the rest of us "sheep" in the sigma 33 procession, all for that starboard /zone moment of glory





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Post Options Post Options   Quote gordon Quote  Post ReplyReply Direct Link To This Post Posted: 15 Jun 10 at 1:25pm
Damp freddie said : "Tactically a port boat on a port rounding could break overlap on a starboard boat on her port quarter by soaking near the zone. If she was left (bouy to her stb) of the mark then she would be entitled to gybe, or if she hardened up at the zone she could gybe."

If port tack boat breaks overlap and is clear ahead when she enters the zone, unfortunately she is not also right of way boat - starboard boat is. Port is only entitled to mark room, which means she must sail straight to the mark - if she hardened up just before entering zone she would have to bear away and sail to the mark. If she luffs above the course to the mark as she enters zone she is taking more mark room than that she is entitled to.

Sailing to the mark means sailing in a straight line from the point you enter the zone to a point just beside the mark where you start to change course to round mark, leaving an seamanlike distance between boat and mark. This may well not be a fast angle of sailing!

Gordon
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Post Options Post Options   Quote jeffers Quote  Post ReplyReply Direct Link To This Post Posted: 15 Jun 10 at 1:03pm

Hence why most good assy sailors will know which way they are round and approach the mark on the appropriate 'tack' to ensure they get an inside overlap.

At the Fireball nationals at Paignton many years ago all the boats were playing the angles downwind because it was so light. We decided to go left and everyone else went right. We took half the fleet and called for water (as it was) and got the reply 'since when?'. I replied 'in theory since we gybed on to starboard about a mile or so away'. Had a chat with the guy after (once he got over his grumpy stage) and he thought it was a genius move (we were helped by the tide and a puff or 2 of wind).

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Post Options Post Options   Quote damp_freddie Quote  Post ReplyReply Direct Link To This Post Posted: 15 Jun 10 at 10:12am
Tactically a port boat on a port rounding could break overlap on a starboard boat on her port quarter by soaking near the zone. If she was left (bouy to her stb) of the mark then she would be entitled to gybe, or if she hardened up at the zone she could gybe.

But that is a very useful clarification Gordon thanks: reminding us that it is "to the mark": see definition "mark room" in the rules. " ....sail to the mark and then sail her proper course"

Suggestion for next version of the rules would be to have the relevant definitions for a rule printed in the pre-amble to each or as a footnote.
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Post Options Post Options   Quote gordon Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jun 10 at 10:22pm
Being doing too much umpiring perhaps - it is on a starboard hand rounding that the port tack boat would be inside.

The principle remains the same  the inside boat  or the boat clear ahead IF she is not also right of way boat (when boat astern is on starboard, and boat ahead is on port) can only sail straight to the mark from where she enters the zone (however slow or uncomfortable that course may be). That does not mean that a port tack boat is allowed to continue to sail a "hot" angle then gybe onto a hot angle on starboard then gyge back - sailing a sort of Z course from where she enters the zone. If sailing to the mark means sailing dead downwind... TOUGH!

As for rule 18.4 - which only applies if boat is inside, overlapped and right of way (that is leeward boat or on starboard) - imagine a starboard boat coming in to a port hand mark at the same time as a port tack boat - she would be inside overlapped and right of way, so entitled to sail a "hot" angle until her proper couse is to gybe, and port boat would have to keep clear. When starboards proper course is to gybe she must do so. If after gybing she is clear ahead she can still do a tactical rounding (enter wide, leave tight), however, if she is now overlapped to windward she is only entitled to sail to the mark not a boatlength or so wide of the mark.

Gordon


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Post Options Post Options   Quote damp_freddie Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jun 10 at 9:23pm
Originally posted by gordon




Finally, it is important to appreciate that an entitlemenent to mark room is not the same thing as right of way. A port tack inside boat at a downwind mark is ONLY entitled to sail to the mark, and at the mark sail her proper course. The starboard tack boat has no obligation to give her any more room that that.



Gordon



A port boat clear ahead you mean: the port boat in the zone has the right to gybe also, and go round the mark in a seaman like fashion... or what ever ( like on the water, not sitting with the wee book right now!) as long as she doesn't drill on down with the kite still up .....

b4 you say she doesn't need to gybe for a port rounding, she may need to gybe twice if she was left of the mark or in flukey winds: what happens then? Allowed two gybes I would say? Bound to have happened in RS400 fleets now it is 3 boat legnths!

Does the same duty to round the mark apply to the starboard boat?: ie fundamental r10 is modified by "shall not sail beyond her proper course" once in the zone at the leeward mark (or a gybe mark for that matter, rare species as they are these days) ?

 Assymetric or mad reaching boats makes this more complicated as to when proper course has been sailed beyond: Until your bow is "south" of the leeward mark you could make a fair claim that you gybed at your chosen point because that was the way you would do it in the abscence of other boats....

So this could mean a fair bit of pushing out in slower assymetric classes reaching in: ie the port boat can be pushed wide and then have to watch the stb boat's gybe and rounding infront of her. The difference from the 2008 rules being all that lovely extra zone surface area!

Phew. Armchair monday....

I think there are some elvestrøm cases on this in the latest (well almost latest!) book
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Post Options Post Options   Quote gordon Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jun 10 at 9:30am
Brass is correct in stating that boats on opposite tacks may be overlapped (according to the definition) when sakiling downwind. However, this has no practical consequence until boats are approaching or in the zone, or approaching an obstruction.

The 2 "open-water" rules that use the concept of overlap (11 and 17) only apply to boats on the same tack.

Approaching a mark - for the first part of 18.2b to apply the overlap must have been clearly established when the boats reach the zone (if there is doubt then 18.2d applies) and, in this case the overlap may be between boats sailing downwind on opposite tacks.

Approaching an obstruction when sailing downwind the outside overlapped boat (irrespective of which tack she is on) must give room. This applies even to a starboard tack boat when inside boat is on port. However, it is important to remember that it is the right of way boat (in this case the boat on starboard) that can choose which side of the obstruction she passes.

Finally, it is important to appreciate that an entitlemenent to mark room is not the same thing as right of way. A port tack inside boat at a downwind mark is ONLY entitled to sail to the mark, and at the mark sail her proper course. The starboard tack boat has no obligation to give her any more room that that.

If the inside keep clear boat, entitled to mark room, sails outside the corridor from where she entered the zone to the mark, or if, at the mark she sails above or below her proper course, her entitlement to mark room does not offer her any protection from her obligation to keep clear.

Gordon

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Post Options Post Options   Quote asterix Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jun 10 at 9:06am

"18.1 When Rule 18 Applies

Rule 18 applies between boats when they are required to leave a mark on the same side and at least one of them is in the zone."

there are some exceptions to this but they don't apply in this case.

Rule 18 applies in this case because the starboard boat has reached the zone (see the first post above).

As Gordon and others correctly say, the starboard boat may (is likely to) have an overlap on a large part of fleet.

"18.2 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. If a boat is clear ahead when she reaches the zone, the boat clear astern at that moment shall thereafter give her mark-room."

So in this case the port boats have to give mark-room

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