Friday, 5 March 2010

LTW Readers Q&A | 038; Virtual Boats at the Windward Mark

A Q&A from Thorsten from Germany about virtual boats. Or are they? Read for yourselves and tell me what you think.

Hi Jos,

While playing virtual skipper (an online regatta simulator), the following situation at the windward mark arose in a fleet race.

Since I had similar situations with a H-Boat from time to time on our lake at home, I think the situation would be possible in real life
I wondered, what rules apply here, given the fact that both boats are head to wind simultaneously in position 3 and both overturn about 5 or 10 degrees.

TB QA 038 windward mark- htw Animation by Thorsten. Here’s the file: TB QA 038 windward mark – htw.gif

In position 1 and 2 rules 11 and 18.2(a) apply, ok. But what rules apply in position 3, 4 and 5?
Both boats are under rule 13 in position 3 and 4, yellow being obligated to keep clear. Rule 18.3 does not seem to apply, since the boats are not on opposite tacks and there is no boat under rule 13 while the other one can fetch the mark.

Since no other rule switches off rule 18.2, to me it seems that rule 18.2(a) is still on. After overturning 5 to 10 degrees, both boats are now on port tack, though not on a close-hauled course. Yellow would be entitled to mark-room including room to tack.

In position 5, blue ignores yellow, turns to round the mark and pushes yellow onto the mark. Without blues manoeuvre and the contact, yellow would have been able to round the mark. Slowly, but still. So it seems to me that blue breaks rules 16.1 and 18.2(a).

I searched the RRS, the case book and the Q&A Service for similar cases, but that was to no avail. I'm wondering if my conclusion is correct, especially the interpretation of rule 18.2(a) and 18.3.
Maybe you can help me out?

Thanks in advance and best regards from Germany,


Dear Thorsten,
I agree with your conclusion but not with the reasoning. The way I play out these scenarios, is to write down the rights, obligations in each position. Make a list of facts as in a protest hearing.

Pos 1: Rule 11, Yellow is ROW - & Blue is Keep clear-boat, keeping clear (barely)

Pos 2: Rule 11 (as in 1) entering the zone, Yellow inside boat with right to mark-room under rule 18.2(b), Yellow can luff to sail to the mark but is still under rule 16.1, so she must give Blue room to keep clear when luffing.

Pos 3: Still rule 11, both are not yet passed head to wind, same as in Pos 2. Yellow still has mark-room and Blue must keep clear (and give mark-room)

Pos 4: Yellow is passed head-to-wind> (NEW) Rule 18.2(c) comes in effect, switching off 18.2(b). We have to go back to the basic rule: 18.2(a).
Both boats are tacking. Rule 13. Yellow on the left so she’s now keep clear boat and Blue is ROW boat. But Blue still must give mark-room to Yellow. Yellow is at the mark and sailing her proper course. She’s entitled to tack with her being windward of Blue who must give mark-room.

Pos 5: Blue bears off. As ROW boat she’s breaking 16.1 and also breaking 18.2(a) by not giving mark-room to Yellow. Yellow breaks rule 13 (not keeping clear as port boat while both boats are tacking) and 31.1 (touching the mark), but is forced to do that by Blue en therefore exonerated under 18.5(b) for rule 13 and 64.1(c) for rule 31.1.

18.3 never enters into this, as the basic premise is never fulfilled: Two boats approaching the mark on opposite tacks.

I hope this answers your question.


Pretty real situation IMHO, wouldn’t you say?
Still in the pipeline: LTW Readers Q&A’s about OCS and Finishing



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