Forum: Rule 18 and Room at the Mark
18.2(b) on Starboard windard rounding opposite tacks
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Greg WilkinsNationality: Australia
Certifications:
- Club Race Officer
- Club Judge
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I'm trying to work out exactly how 18 works for a windward rounding when two boats approach on opposite tacks: A on starboard layline and tacks in her zone and B on port layline and in her zone. Here is my thinking so far:
EDIT: [
Mark is a windward mark to be left to starboard.
Boat A approached on starboard lay line and must tack in the zone to round the mark.
Boat B approaches on the port lay line and does not need to tack.
Indeterminant who reached the zone first... let's say about the same time.
]
EDIT: [
Mark is a windward mark to be left to starboard.
Boat A approached on starboard lay line and must tack in the zone to round the mark.
Boat B approaches on the port lay line and does not need to tack.
Indeterminant who reached the zone first... let's say about the same time.
]
- 18 doesn't apply initially by 18.1(a) & (b), since they are on opposite tacks to windward.
- Once A has passed head to wind, then the boats are now on the same tack, so the exclusions in 18.1 no longer apply and rule 18 switches on.
- 18.2(a) will apply unless 18.2(b) does...
- 18.2(b) does not apply. When the first of the boats reached the zone (either A or B), they were on opposite tacks and thus can't be overlapped as they are not 90 degrees from the wind. Also neither can be clear ahead when they reached the zone as that can't geometrically happen if both boats are on lay lines (unless one of them is already passed the mark).
- 18.2(c) doesn't apply as 18.2(b) doesn't
- 18.2(d) is meaningless without (b) or (c).
- 18.2(e) does apply, but is less so without (b). However it can still be applied to considerations of (a).
- 18.2(f) may apply.
- 18.3 doesn't apply when A tacks in the zone because it is a starboard rounding (and 18 wasn't applying yet anyway).
- 18.4 doesn't apply as gybing at an upwind mark is not the proper course!
Thus it is just 18.2(a), (e) & (f) that apply (plus 10-17 of course). Specifically:
- if either boat establishes an inside overlap (within doubt given by 18.2(e)) then the other must give her mark-room by 18.2(a) unless 18.2(f) applies and it is not possible to do so.
- If either boat establishes an inside overlap from clear astern, then she is constrained by 17 and has to sail her proper course and round the mark.
- If B's gets the inside overlap due to A's tack, then she is not constrained by 17 and can sail past the mark.
- If one boat reaches the mark clear ahead of the other, then 18.2(a) doesn't apply and neither are owed mark-room.
- But when a boat clear-ahead at the mark bears away to round the mark she may be constrainted by 16 to give the other some room to keep clear. Also it is a possible that the bear away establishes an overlap and 18.2(a) switches back on and mark-room is also owed to the now inside boat.
Is that about right?
Comments
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John
Is this a port rounding?
I understand that 18.1(a) means that 18 does not initially apply, but I believe 18 does apply after A has tacked.
sorry I didn't prepare a diagram because this is not about a specific instance, but more a general one.
It is a windward mark that must be left to starboard.
A approached on the starboard lay line and needs to tack in the zone to round the mark.
B approached on the port lay line and does not need to tack.
18 does not initially apply because they are on opposite tacks.
I am asking how/if/why/when 18 applies after A has tacked so they are on the same tack.
You can add R15 while A is subject to R13 or when B becomes inside overlapped due to any bear away by A after reaching CHC om port. However, R15 does not apply in these two instances because B acquired ROW due to A's own action.
If B gains that inside overlap she will have mark room from the moment A passes HTW to port but possibly not if A is unable to give it. However, in this case A must keep clear R13 or R11 and R15 does not apply.
If A then subsequently breaks R13, 15,16.1 etc or hits the mark breaking R31 she might be exonerated by R43.1b depending upon the interpretation of 'as a consequence of an incident etc'.
I think your analysis is right. Rule 18.1(b) excludes Rule 18 only as long as the boats are on opposite tacks. After A's tack, Rule 18 begins to apply.
If A, after her tack establises an inside leeward overlap with B, Rule 18.2(a) applies (because 18.2.(b) does not. Under this Rule, A would be entitled to mark room.
However, at a port rounding, this result is modified by Rule 18.3, saying that A shall not use B to sail above close-hauled. At a port rounding A is therefore not entitled to mark room. At a starboard rounding, Rule 18.2(a) is not modified by Rule 18.3.
The consequence is that there are different results, depending on the rounding direction:
I think the idea for that different result is the fact that at a port rounding B approaches on starboard tack, i.e. as the right of way boat, whereas at a starboard rounding B approaches on port tack - and is therefore less worthy of protection versus A.
In this situation, it is 16.1 which limits A relative to B while A is luffing to tack. Note that 16.2 now includes “.. bear away ..” in the 2021 quad. Luffing is the opposite of bearing away therefore 16.2 does not apply.
Also, 15 will not apply to B while 13 applies to A as B acquires ROW by A’s (the other boat’s) action.
Ang
Greg Wilkins