Tuesday, 23 February 2010

Looking for 18.1(b)

Not long ago during a presentation I was asked to give an example of rule 18.1(b). I must confess I was not able to come up with one that was not also already covered by 18.1(a). I've been thinking about it after that, but could use some help.

Lets start at the beginning:

Rule 18.1 is the rule that tells us when rule 18 applies. There are four bullets, from (a) to (d):
The first one is easy enough. For boats on different tack on a beat, approaching a windward mark, there's no rule 18, until one of them changes tack

The third one has been added in the latest rule cycle, but most people already applied it before. No rule 18 between a boat approaching and a boat leaving a mark.

The fourth bullet (d) tells us that in case the mark is also a continues obstruction, rule 19 applies and not rule 18.

That leaves the second one, rule 18.1(b):
Rule 18 does not apply between boats on opposite tacks when the proper course at the mark for one but not both of them is to tack.

The one I came up with was a starboard tack boat on a reach toward a mark and a port tack boat on a beat about to round the same mark. Something like this:

Rule 18 is off until the Orange boat passes head to wind. Then she becomes inside boat entitled to mark-room. If Purple has to avoid Orange before she's passed head to wind; penalty on Orange
If Purple only has to respond after Orange has passed head to wind, no infringement, no penalty.

READ UPDATE in Comments!
(J. 23/02/10; 21:33 h)

Can you find other situations where rule 18.1(b) is applicable?


  1. How about coming into an offset mark where, perhaps due to a windshift, the leeward boat is not fetching but the windward boat is... Now the leeward boat tacks onto port, and is not entitled to mark-room because her proper course at the mark is to tack back onto starboard.

  2. There is a very good explanation on sailingword: link

  3. This is the theme I have been waiting for a long time.
    The situation that I was thinking away to myself is the same as Jos's one.
    The 18.1(b) is similar to 18.1(a), but not same.
    I felt much better now that a long-pending question was settled. Dank U.
    sen yamaoka

  4. Dear Jos,

    I think that your explanation after Orange changes tack within the zone should also take in consideration RRS18.3 Tacking when approaching a mark.
    I would propose the following text "If Purple only has to respond after Orange has passed head to wind, no infringement, no penalty, provided Orange did not break RRS18.3 (e.g. Shall not cause the other boat to sail above close-hauled to avoid her...)
    J. Cantero

  5. @anonymous2
    Thanks for the link! I checked my files about this issue but didn't think to look back before 2009.

  6. But what is the definition of "on a beat to winwards"?

    Is the SI or NOR required to define each leg as a beat to winword or not?

    What happens if is there a wind shift? Is it a leg to be consider according the planned wind or the real wind?

  7. @J. Cantaro
    Yes, good point.
    Orange is subject to rule 13 within the zone.
    But if we use rule 18.3 and I think we must, then rule 18.2 does not thereafter apply!

    Which means that only the rules of section A and B apply. No mark-room for Orange as inside boat!

    Orange has to keep clear during whole tack until she's on her new close hauled course and then rule 15 dictates she initially must also give room to Purple to keep clear.
    The way I've drawn the picture she is breaking 13 for sure.

    I don't think there's a big chance that Orange will cause the other boat to have to sail above close hauled, since Purple was reaching. But you are right, it is also a rule that Orange has to follow.

    (Should have drawn the zone in the diagram, I guess)

  8. @Anonymous3
    You can find your answer in Q&A 2004-006.
    I've copy-pasted the text below:

    Q&A 2004-006
    Revised: 12 January 2009
    Except on a beat to windward, rule 42.3(c) permits a boat to pull the sheet or guy to initiate surfing or planing. When is a boat on a beat to windward?
    The phrase 'on a beat to windward' is used in rules 18.1(a) and 42.3(c). For the purposes of each rule, a boat is 'on a beat to windward' when her proper course is close-hauled; when she is 'beating.' Therefore, if a boat is sailing on a leg to the windward mark and the wind direction changes so that the boat's proper course to the mark is no longer close-hauled, then the boat is no longer 'on a beat to windward.'
    Similarly, when a boat is sailing on a downwind leg and there is a wind shift so that it is clear the boat’s proper course to the mark is close-hauled, then the boat is 'on a beat to windward'. When judging this, the last point of certainty principle is used. For example, a boat approaching a windward mark on the starboard tack layline gets a lifting shift. The judges need to be certain that the boat’s proper course is no longer close-hauled before permitting 'one pump per wave'. If there is any doubt, the judgment will be that the boat is still 'on a beat to windward'.

  9. I think rule 18.3 does not apply to this situation. Because if the exception in rule 18.1(b) applies, rule 18 does not apply.
    When rule 18 does not apply, the rules in Sections A (R-O-W) and Section B (General limitations) apply.
    So Orange needs to keep clear of Purple under rules 10, 13, 15 and 16 first, and then Purple needs to keep clear of Orange under rules 11 and 16.
    sen yamaoka

  10. How about this: two boats are approaching the windward mark on starboard tack, the leeward one clear ahead as they reach the zone. L would normally be entitled to mark room but if he is below the mark and has to tack to fetch it, 18.1b turns 18 off. or the same scenario but overlapped, L would be entitled to mark room if he could pinch around the mark with favourable current but if he tacks 18 turns off and 13 and 10 take over,

    George Morris

  11. The difference between rrs 18.1(a) and 18.1(b) can be seen on three exmaples:
    Example 1:
    Windward mark to be rounded on port.
    18.1(a) as well as 18.1(b) apply between a port and a starboard boat.
    Example 2:
    Finishing mark at a the end of a windward leg.
    18.1(a) apply but not 18.1(b) between a port and a starboard boat.
    Example 3:
    Mark 2 on a trapezoid course.
    Only 18.1(b) but not 18.1(a) apply between a port boat coming form mark 3 and a starboard boat coming from mark 1.

  12. Dear Uli;
    Please excuse me for my long silence.
    Thank you for your answer. I see!
    sen yamaoka

  13. @Sen in comment 9
    Boats are usually always moving. Therefore the rules have to be applied anew in every transition. Rule 18.1 must be tested in every new situation. Once boats or no longer in one of the four 'exceptions', rule 18.2 or 18.3 dictate the rights and obligations.
    I'll try to set up a flowchart.

  14. I would agree that rule 18 is switched off until Orange passes head to wind. However rule 18.3 refers to rule 13. Rule 13 applies until Orange is on a close hauled course.

    But whilst passing from head to wind to the close hauled course I think that the provisions of 18.3 would apply and Orange would be binned until she was on a close hauled course.

    So in that situation, if Purple has to respond after Orange is on a close hauled course she can do so without penalty provided that she gives mark-room.


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