unless the SIs specify a required side to round when only one buoy of a gate is present, the remaining buoy is not a mark and a boat can round in either direction.  I would consider abandoning in that event.

I think you have to abandon.

The ideal solution would be to get a mark boat in place quickly with a Mike flag and multiple, repeating sound signals.  They don't necessarily have to be anchored as long as they can reasonably hold position.  Obviously, anchoring would be ideal, but I've never seen the "missing mark" flag used leisurely.  You're always in a hurry.

Absent that or an instruction in the SIs - you certainly have cause to abandon, but there's nothing that says you have to.

(The "Q&A" you may be thinking of is WS Case 82, but that applies to ambiguous finish lines, not gates.)

Agree. RC should Abandon or mark-boat stand as replacement. 

The question is would a racer know to abandon racing if they get there before noticed by RC?  

Would it be worthwhile for Rule 34 to speak to either a port-rounding default or abandonment in this case, for safety-sake? - Ang

curious, why abandon?  Doesn't RRS 18 kick in for everyone to round the mark?

TJ it doesn’t have a specified side, unless they were different shapes/colors where a competitor could tell the diff between the left/right gate (very atypical). 

PS: Also the SI’s would have to been written such that the marks’ distinctions were described as well as their “side”. 

RRS 28.2(c).  Pretty sure once one of the marks of a gate is gone, the remaining gate buoy is no longer a mark 

the concept of "a gate with one mark missing is no more a mark" is interesting.
Thanks
So is a must to state in the SIs this possibility, and how to cope.
Though, if the fleet is already scattered when one buoy disappear, and some boat take the remaining buoy on port, other boats on starboard, well, maybe no need to abandon the race. Maybe.

I've seen SIs state " In the event one of the gate marks is missing, the remaining mark shall be rounded to port "

That's a very big "maybe."  As a race officer, I avoid creating redress situations if at all possible.  That's just asking for a redress hearing.

Wait a minute!  Just playing devil's advocate here, but I think the mark has a required side.  There was a course diagram, showing boats rounding the right-hand mark to starboard and the left-hand mark to port.  (Note that when a boat passes through the gate, she satisfies both those requirements.)  So if the remaining mark is the one to be rounded to starboard, then boats rounding the mark to port are not sailing within the room to which they are entitled.  They'd better obey the rules of Section A, as well as rules 15 and 16, because there's no exoneration for them!  And if they don't unwind their strings, they won't have sailed the course.  

Of course, there's the problem for the boats, of determining which mark is still there.  As Angelo says, we could make the gate marks different colors.  Why don't we commonly do that? 

As Matthew points out, many SIs have a provision saying that if one gate mark is missing, the other is to be left to port.  If there is such an SI, no effort should be made by the RC to replace the missing mark until everybody is around it.

yeah, I think the problem is when we assume that the competitors know which gate buoy is missing.  The definition of mark controls a little as well: "An object the sailing instructions require a boat to leave on a specified side"  By the rules, a gate doesn't have specified side...just that boats must "pass between".

Rob, “As Angelo says, we could make the gate marks different colors.  Why don't we commonly do that? “

Wouldn’t that be handy if we developed the custom of Red/Green gate marks?

PS: Matthew that goes to my other comment, it depends on how the gate is described. Often it is described as Rob indicates ... pass R to STB AND L to port this going between satisfies.  Actually, come to think about it, if one of those are missing, you can’t satisfy one of those requirements. 

You could do it, but you've now placed another burden on the RC to get it right - and you take away a commonly used mechanism for a minor gate adjustment - the "flip-flop" (moving one mark to the opposite side of the other, which typically does not require signalling a course change at the weather mark).

I wouldn't want to be in the redress hearing when the RC gets the marks mixed up.

Also, what about red/green color blindness?  Are you going to have a green tet and a red tomato?  I foresee an MBO revolt.

well, so far, a SI that says to round the remaining buoy at a specific side is good and clear enough. 
My original question refers only when SI says nothing about it.
Good point the redress line out of Jury room to attend. Surely to be avoided.
Thanks you all

If one of the gate marks is missing competitors are no longer able to comply with rule 28.2(c), so the mark is missing. The RC should proceed in accordance with rule 34.

Mark T. That’s a really good point when considering SI language that attempts to anticipate a missing gate mark and say the remaining mark should be rounded to port. 

Should such an SI call out that it changes 28.2(c)?

Mark T. - Would I be right in thinking you meant to say "The RC should proceed in accordance with rule 34."?

The race committee should do the same thing that they do if the weather mark is missing; (a) replace it in its correct position or substitute a new one of similar appearance, or (b) substitute an object displaying flag M and make repetitive sound signals. When race committee gets overly creative they usually confuse the sailors and end up with a visit to the protest committee because someone wants redress. Always remember, no good deed goes unpunished!

If the SI anticipate a missing gate mark and say the remaining mark should be rounded to port, at what time do we consider that a drifting  gate mark, and more precisely a gate mark to be left on port, is missing ?

The underlying issue here is that the race officer should never put him/herself in this position. There should be a mark boat nearby ready to comply with rule 34 and if that isn't possible, have the statement in the SI dealing with rounding the remaining mark in the event the other is missing. If you don't, you risk having the race tossed and it's shame on you. 

I agree with John A that the race officer and race committee should have a mark set boat nearby ready to comply with rule 34. My experience has been that the mark is out of position, having been hooked on the keel or rudder of a boat, rather than missing. Given a choice, I tend to avoid having an SI dealing with rounding the remaining mark in the event the other is missing, as it causes additional confusion and debate as to if the mark is missing or merely out of position, and you also need to deal with rule 28.2(c) if it is missing.

I think it is always good practice to put a default in, in case one mark of a gate is missing. You do not want to lose a race, especially if it is a gate at 4 on a trapezoid and half the fleet finishes and some then do not any you have to deprive someone of a win.

Mike B, as I have been ruminating on your ‘1/2 the fleet’ comment, I wonder if it is actually a fair-race to have some boats have the option of the gate and others, not.   What if the missing gate was favored due to a wind-shift?  I’d argue that these boats actually did not sail the same course. 

I also came to similar thoughts when considering what may be on the new quad and how it might impact this discussion. Assuming the new definition “Sail the Course” survives to the published 2021 quad, (as we saw it in the ‘Draft 1’ that was published) having “a default” in the SI’s might be a little trickier to word.  Somehow one would have an SI that converts the remaining gate-mark to a rounding-mark without touching the new “Sail the Course” definition. 

Maybe one approach would be to think about the change of the gate to a rounding-Mark as a ‘change of course’ ... but one can’t do that in the middle of a fleet. 

Ang

I was thinking of half the fleet as being those on the outer loop who complete their race, not those on the same course. So we have boats on different courses (inner loop and outer loop) who are scored as in the same race so I see rounding only one gate mark as no problem.
The rya recommend
 A problem arises if a mark is missing and has not been replaced in a manner specified in RRS 34, which requires substitution with a similar mark or an object displaying flag “M”. ISAF Question and Answer 2009-034 says that with only one mark remaining there is no gate and the remaining mark has no required side. The consequence of this is likely to be abandonment of the race. To avoid this problem, race committees are recommended to specify a required side when only one mark of a gate is present so that there will still be a mark with a required side. Boats would then round the remaining mark as any other single rounding mark. 
The suggested SI to be inserted in the courses section is: A gate may be replaced by a single mark to be left to port (or starboard). 

Q&A 2009 034!!! That's what I was looking for. Thanks. It resumes rather well the situation. Thanks very much Mr: Michael.