August 2011 - Port Over Starboard II

placeholder image

August 2011 - Port Over Starboard II

Last month I discussed the situation at a leeward mark where a starboard-tack boat has to give room to a port-tack boat. Before I continue with situations where starboard tack has to give way to port tack, I want to show two situations that may seem similar to last month but which are not. In last month’s situation, starboard had to give “mark-room” to port according to rule 18.2. Rule 18.1 describes when rule 18 applies and more importantly where it does not.


Section C rules do not apply at a starting mark surrounded by navigable water or at its anchor line from the time boats are approaching them to start until they have passed them. When rule 20 applies, rules 18 and 19 do not.


18.1     When Rule 18 Applies
Rule 18 applies between boats when they are required to leave a mark on the same side and at least one of them is in the zone. However, it does not apply
(a)        between boats on opposite tacks on a beat to windward,
(b)        between boats on opposite tacks when the proper course at the mark for one but not both of them is to tack,
(c)        between a boat approaching a mark and one leaving it, or
(d)        if the mark is a continuing obstruction, in which case rule 19 applies.

(click on the diagram to see a larger cleaner version)

In the diagram we have the red boat on port tack approaching a weather mark. Green is approaching on starboard tack. They are therefore on opposite tacks on a beat to windward and the proper course for the red boat, but not the green boat, will be to tack to round the mark, so rule 18.1a and 18.1b both say that rule 18 does not apply. This means that the green boat will not have to give mark-room to the red boat and as the port-tack boat, red will still have to keep clear (just as if the mark was not there).

The second situation is closer to the leeward mark I showed last month. It is also much less common. I did however see it happen in two Friday night TGIF races this spring.

(click on the diagram to see a larger cleaner version)

The start was downwind. The blue boat was coming into the committee boat on port tack. The yellow and white boats were approaching on starboard tack. The preamble to section C says that the rules of section C do not apply at a starting mark surrounded by navigable water … from the time the boats are approaching to start”. Since they are all “approaching the starting line to start” rule 18 does not apply. Blue has got herself into hot water here. She is not entitled to mark-room and as port-tack boat should be keeping clear according to rule 10 (opposite tacks). We don’t see this situation very much since we don’t see downwind starts very often. This situation is very similar to barging on a normal upwind start. There again, rule 18 does not apply, so the rules of part A rule 11 (same tack overlapped) do apply.

© Copyright 2011 Andrew Alberti
Posted: 8/1/2011 1:49:32 PM by Andrew Alberti

Trackback URL:

This page provides links to a set of articles original published in Kwasind magazine. The versions here include animated diagrams. The original articles can be found within the original magazines which are available online back to January 2007. 

Articles before December 2020 are based on the Racing Rules of Sailing 2009-12 or 2013-2016 or 2017-2020 and have not been updated to reflect the changes that apply as of January 2021 with the publication of the Racing Rules of Sailing 2021-24. A copy of the new rules can be found on
Andrew Alberti has been writing these monthly articles in the Kwasind since early 1997.  They explain the Racing Rules of Sailing. Andrew is an International Judge and National Umpire. He is a member of the Sail Canada Rules and Appeals Committees. The interpretation of the rules contained in the articles is Andrew's and not that of the RCYC or any of the committees he sits on. 

Send your questions to Andrew at [email protected].


166 Years of Tradition | World-Class Sailing | Toronto Island & City Clubhouse
After You Cross The Finishing Line I
Tacking III
Tacking II
Publication Changes and Tacking
How to Finish
Post Archive
May 2024(0)
May 2024(2)
March 2024(1)
February 2024(1)
May 2023(1)
September 2023(1)
September 2023(0)
May 2023(0)
January 2023(1)
April 2022(1)
December 2021(1)
October 2021(1)
August 2021(2)
March/April 2021(1)
January/February 2021(1)
December 2020(1)
November 2020(1)
September 2020(1)
July 2020(1)
June 2020(1)
May 2020(1)
March/April 2020(1)
January/February 2020(1)
November/December 2019(1)
September/October 2019(1)
July/August 2019(1)
May/June 2019(1)
March/April 2019(1)
January/February 2019(1)
November/December 2018(1)
September/October 2018(1)
July/August 2018(1)
May/June 2018(1)
March/April 2018(1)
January/February 2018(1)
November/December 2017(1)
October 2017(1)
September 2017(1)
August 2017(1)
July 2017(1)
June 2017(1)
May 2017(1)
April 2017(1)
March 2017(1)
January/February 2017(1)
December 2016(1)
November 2016(1)
October 2016(1)
September 2016(1)
August 2016(1)
July 2016(1)
June 2016(1)
May 2016(1)
April 2016(1)
March 2016(1)
January/February 2016(1)
December 2015(1)
November 2015(1)
October 2015(1)
September 2015(1)
August 2015(1)
July 2015(1)
June 2015(1)
May 2015(1)
April 2015(1)
March 2015(1)
January 2015(1)
December 2014(1)
November 2014(1)
October 2014(1)
September 2014(1)
August 2014(1)
July 2014(1)
June 2014(1)
May 2014(1)
April 2014(1)
March 2014(1)
January 2014(1)
December 2013(1)
November 2013(1)
October 2013(1)
September 2013(1)
August 2013(1)
July 2013(1)
June 2013(1)
May 2013(1)
April 2013(1)
March 2013(1)
January 2013(1)
December 2012(1)
November 2012(1)
October 2012(1)
September 2012(1)
August 2012(1)
July 2012(1)
June 2012(1)
May 2012(1)
April 2012(1)
March 2012(1)
February 2012(1)
January 2012(1)
December 2011(1)
November 2011(1)
October 2011(1)
September 2011(1)
August 2011(1)
July 2011(1)
June 2011(1)
May 2011(1)
April 2011(1)
March 2011(1)
February 2011(1)
January 2011(1)
November 2010(1)
October 2010(1)
September 2010(1)
August 2010(1)
July 2010(1)
June 2010(1)
May 2010(1)
April 2010(1)
March 2010(1)
February 2010(1)
January 2010(1)