Wednesday, December 19, 2012

A New Rule Interpretation by Dave Perry - Keep Clear

Rules authority Dave Perry helps explain some of the significant changes to The Racing Rules of Sailing for 2013-2016. Perry is chairman of the US Sailing Appeals Committee, and has served as Rules Advisor to the US Olympic Sailing Team.

Definition of 'Keep Clear' Expanded...
The second part of the definition 'Keep Clear' has been expanded to apply to port and starboard tack boats as well as windward and leeward boats. If a port-tack boat allows herself to get so close to a starboard-tack boat that the starboard-tack boat cannot change course in both directions without making immediate contact with the port-tack boat, the port-tack boat has failed to keep clear. This commonly occurs when the boats are sailing dead downwind.

Keep Clear - A boat keeps clear of a right-of-way boat
(a) if the right-of-way boat can sail her course with no need to take avoiding action and,
(b) when the boats are overlapped, if the right-of-way boat can also change course in both directions without immediately making contact.

Purchase the new Waterproof edition of The Racing Rules of Sailing for 2013-2016. 


  1. Does this mean that a port-tack boat on a beat must cross a starboard tacker far enough ahead so the starboard tacker has room to luff as they cross? If so, this is a significant change to the rules that apply to such crossings.
    - Gary Thorne

  2. From Dave Perry:

    Thanks Gary...I should have pointed out that the new language in the definition Keep Clear applies only to "overlapped" port and starboard tack boats. Boats on opposite tacks are not considered "overlapped" under the rules unless rule 18, Mark-Room, applies, or both are sailing more than ninety degrees from the true wind (see definition Clear Astern and Clear Ahead; Overlap).As rule 18 does not apply between boats on opposite tacks on a beat to windward (see rule 18.1(a)), the change to the definition Keep Clear applies only to port and starboard tack boats when they are sailing downwind below ninety degress to the true wind.

    For more on the rules, get Dave Perry’s two books Understanding the Racing Rules of Sailing through 2016 (which includes the complete rule book) and Dave Perry’s 100 Best Racing Rules Quizzes available at US Sailing, 800 US SAIL-1, or

  3. How about downwind? Many boats gybe through wide angles downwind. Can a boat on starboard tack suddenly sail below her normal VMG course in a crossing situation in order to draw a foul from a boat on port tack?
    -Steve Shumaker

  4. Hi Dave! Following up on Gary's thread, the next question is: does this mean that when running, the port tacker that intends to cross has to leave extra room to allow the starboard tacker to be able to change course at the last second by bearing away? Previously, a last-second hunt was prohibited by RR 16.1, right?

  5. From Dave Perry:

    Rule 16.1 requires a right-of-way (r-o-w) boat room to keep clear when she changes course. The rule writers realized it would be unfair if a keep-clear boat could put herself so close to a r-o-w boat that the r-o-w boat could not physically change course without immediately breaking rule 16.1. The language in the definition Keep Clear is intended to solve that. If sailing downwind, a port-tack boat (P) tries to pass so close in front of a starboard-tack boat (S) that S can bear away and "immediately" hit her, then P is not keeping clear of S by definition, and is breaking rule 10. If P is crossing a little further away such that S *can* bear away without "immediately" hitting her, then S is allowed to bear away to try to prevent P from crossing her, but she has to give P the space and time P needs to promptly maneuver away from S in a seamanlike way.

  6. In the new expanded definition of Keep Clear, the word "both" is a bit confusing. My Dad interprets the meaning to be inclusive of heading up and heading down. I read it as meaning if S can do either, head up or down without immediate contact, there is no infraction. Would it not be better to use "either" instead of "both" if my dad is right?