September 2011 - Port Over Starboard III

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September 2011 - Port Over Starboard III

This month I am going to continue to show situations where starboard-tack boats have to keep clear of or give room to port-tack boats. 

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

In the diagram, the blue and red boats are both sailing upwind on port tack (the “red” boat changes colour from red to green to yellow to denote its tack and status – I’m going to call it the red/green/yellow boat unless I’m referring to a particular position or status, when I’ll refer to a single colour). The red boat luffs up at position 3. At position 4, she crosses head to wind and becomes a starboard-tack boat (shown in green). At position 6, she gets onto a close-hauled course (shown in yellow). From position 4 until position 6, she has to keep clear of blue according to rule 13.
After a boat passes head to wind, she shall keep clear of other boats until she is on a close-hauled course. During that time rules 10, 11 and 12 do not apply. …

A boat shall avoid contact with another boat if reasonably possible. However, a right-of-way boat or one entitled to room or mark-room
(a)        need not act to avoid contact until it is clear that the other boat is not keeping clear or giving room or mark-room, and ….

When a boat acquires right of way, she shall initially give the other boat room to keep clear, unless she acquires right of way because of the other boat’s actions.

At position 6, even though her sail is luffing, the yellow boat is on a close-hauled course, so rule 13 stops applying and she becomes a right-of-way boat. Since yellow has just become right-of-way, she initially has to give the blue boat room to keep clear according to rule 15. Accordingly, blue should now alter course to keep clear. If blue has to alter course to keep clear before the red/green/yellow boat achieves a close-hauled course, then red/green/yellow is at fault even though green was on starboard and blue was on port. I should also note that as soon as it is clear to blue that the other boat is not going to keep clear, she should alter course to avoid the collision as required by common sense and rule 14.

Rule 21 discusses a number of exception situations. Rule 21 is part of Section D. The preamble to Section D says that when rule 21 applies, Section A rules (which includes the port-starboard rule) do not apply. This month we will look at rule 21.1.


When rule 21 or 22 applies between two boats, Section A rules do not.


21.1     A boat sailing towards the pre-start side of the starting line or one of its extensions after her starting signal to start or to comply with rule 30.1 shall keep clear of a boat not doing so until she is completely on the pre-start side.

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

In the diagram, the starting signal goes at position 1. Yellow on starboard tack is already partly over the line. At position 3, she starts to sail back towards the pre-start side of the line to start. According to rule 21.1, even though blue is on port-tack, yellow has to keep clear of her. Note, though that yellow didn’t lose her right-of-way until she was heading towards the pre-start side of the line or one of its extensions, which is just before position 3. Until then, blue must keep clear.

© Copyright 2011 Andrew Alberti
Posted: 9/1/2011 1:43:31 PM by Andrew Alberti

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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
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