September/October 2018 - What Tack Are You On?

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September/October 2018 - What Tack Are You On?

The first right-of-way rule (rule 10) covers right-of-way between boats on opposite tacks. To use this rule, we must know which tack boats are on. Most of us know that, if the wind is coming over the starboard side, we are on starboard tack. Sometimes it is not so obvious, and the resulting ambiguity may create confusion, and occasionally, exploitation.

Tack, Starboard or Port  A boat is on the tack, starboard or port, corresponding to her windward side.

Windward  See Leeward and Windward.


Leeward and Windward  A boat’s leeward side is the side that is or, when she is head to wind, was away from the wind. However, when sailing by the lee or directly downwind, her leeward side is the side on which her mainsail lies. The other side is her windward side. When two boats on the same tack overlap, the one on the leeward side of the other is the leeward boat. The other is the windward boat.



When boats are on opposite tacks, a port-tack boat shall keep clear of a starboard-tack boat.



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. If two boats are subject to this rule at the same time, the one on the other’s port side or the one astern shall keep clear.

The rule book takes several steps to define which tack a boat is on. First is the definition of “Tack, Starboard and Port”. This is found in the Definitions section of the rulebook. It says that the tack a boat is on is based on her windward side. Next is the definition of Windward, which not very helpfully, says to look up the definition of “Leeward and Windward”. Finally, this definition tells us how to tell which the boat’s leeward side is and says the other side is her windward side.

In position 1 of the first diagram, the two boats are sailing close-hauled towards each other. Yellow is on starboard tack and Blue is on port tack. At position 2, both boats start to luff. Their sails are no longer full but according to the Definitions, they are still on the same tack as they were on in position 1. At position 3, they are both head to wind. They are exactly parallel and neither has crossed head to wind. The definition says “A boat’s leeward side is the side that, when she is head to wind was away from the wind”. This means that Yellow, whose port side was way from the wind in position 2, is still on starboard and Blue, whose starboard side was away from the wind in position 2, is still on port tack. The moment they pass head to wind, they change tacks and are subject to rule 13 instead of rule 10.


In position 1 of the second diagram, we see two boats sailing downwind toward each other. The wind is coming over Green’s starboard side so she is on starboard tack; Red is on port tack. Both boats bear off onto a run in position 2. They are now parallel. Green has her boom on the port side and according to the definition “when sailing directly downwind, her leeward side is the side on which her mainsail lies.” This means Green is still on starboard tack.  Red is still on port tack. As they turn even further to position 3, they are now both sailing by the lee (this is very common in single-sail boats such as Optimists, Lasers and even Nonsuches). The definition covers this as well. “When sailing by the lee her leeward side is the side on which her mainsail lies.”  Even though the wind is now coming over Green’s port side, she is still on starboard tack, since her mainsail is on her port side. At position 4, the wind caught the other side of the originally Green boat. Her crew works hard to hold her boom onto the port side, but now that the wind is blowing the other way in the mainsail, her sail no longer “lies” on the port side. This boat is now on port tack. Judges consider the mainsail to lie on the port side when it would stay there without being held; if the mainsail would stay on the port side only by virtue of being held, the boat is not on starboard, regardless of what its crew may say.


When sailing downwind it is very important to think about which tack you are on and which tack others around you are on. Pink and Purple are sailing parallel to each other and Pink is overtaking Purple, but Pink has right-of-way since she is on starboard tack and Purple is on port tack.

© Copyright 2017 Andrew Alberti


Posted: 5/1/2019 8:47:05 AM by Andrew Alberti | with 0 comments

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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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