Tacking on a mark, room to keep clear?

18.2b: 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.

Either of the above is probably OK. The way I was told to do this was to go head to wind until the other boat has gone astern then go through to complete the tack (so like your second option but doing it at the mark). It would depend on tactical considerations for the next leg as to what the best thing to do would be. 

For example it may have been better tactically to let Yellow tack inside and you tack on top to keep a clear lane and yourself in the best tactical position to keep them behind you (depending on which way the next mark was to be rounded).

That's what I don't really get, do you really take any more room to tack around a mark than gybe, or just head up from DDW to close hauled? I imagine the stern swinging out just as much as in any scenario. So it seems weird that the rule say you don't have room for it. 

Sorry guys, but this discussion is yet again highlighting the problems caused by using language that is not in the rules.

The rules do not use the word "tacking" or the phrase "complete a tack", nor do they say that, in any circumstances mark-room "includes a tack".

Originally posted by mozzy Blue (B) clear ahead of Yellow (Y) and slightly to leeward at 3 boats, both boat over the port layline on port. Proper course for both boats is to tack on the mark.  18 applies before B tacks and Y is clear astern so must give B mark room. Rule 21 exonerates B whilst sailing in her mark room for Section A plus rules 15 and 16.  But, at which point is B tacking and therefore not sailing within her mark room? As diagrammed, B is always sailing within the mark-room to which she is entitled. @3 + delta she will have passed head to wind and rule 18, in its entirety ceases to apply (Case 95). @2, B is sailing in to the mark. @3 B is sailing as necessary to round the mark. Between @2 and @3 B is sailing within the mark-room to which she is entitled, and she can change course to round the mark as hard and as fast as she likes and will be exonerated by rule 21 if she breaks rule 16. Between @3-delta and @3, as others have said, B can slow her turn and speed as she chooses and force Y to go around her, as long as she does not pass head to wind. And at which point are they on port and starboard and so 18 no longer applies? When B has passed head to wind. Ignoring the mark the boats are going fast enough that Blue can't complete their tack and give yellow room to keep clear, so would either break 13 or 15. or B would break rule 16 if she comes up so hard that she doesn't give Y room to keep clear. But as they are approaching the mark, and B was clear ahead Y should be giving blue mark room right up until position 3 Yes. AND keeping clear (rules 12 then 11) (or maybe after when the tack is complete?)? No. Mark-room goes off when B passes head to wind The situation could be on a tight reach to mark your course requires you to tack around or two boat over-standing a port layline.

This example, with B on the layline, and able to come head to wind at the mark, contrasts with Case 15, where the boat clear astern was able to pin out the boat ahead,

Case 15
Definitions, Mark-Room
Rule 12, On the Same Tack, Not Overlapped
Rule 13, While Tacking
Rule 18.1(b), Mark-Room: When Rule 18 Applies
Rule 18.2(b), Mark-Room: Giving Mark-Room
Rule 18.2(c), Mark-Room: Giving Mark-Room
In tacking to round a mark, a boat clear ahead must comply with rule 13; a boat clear astern is entitled to hold her course and thereby prevent the other from tacking


Edited by Brass - 20 May 19 at 11:00pm

Originally posted by Brass Mark-room never "includes a tack". It may include "room to tack" but this only applies until the boat passes head to wind and mark-room ceases.