See below for full details of the rule change.
In simple terms when boats are sailing to the offset mark, leeward mark or to the finish line if they gain an overlap to leeward they can sail above their proper course, except when the boat is the outside boat when approaching a mark and having to give room.
This change was trialled in France in November and was a great success.
There will be changes to some tactics.
This was originally trialled by the World Match Race Tour, and is now part of the new ISAF trial rules for Match Racing.
Change to Rule 17
“Rule 17 is changed to ‘After the starting signal, if a boat clear astern becomes
overlapped within two of her hull lengths to leeward of a boat on the same tack, she shall not sail above her proper course while they remain on the same tack and overlapped within that distance, unless in doing so she promptly sails astern of the other boat.
This rule does not apply if the right-of-way boat is on a leg to a leeward mark or the finishing line,
or if the overlap begins while
(a) the right-of-way boat is on a leg to a leeward mark,
(b) the windward boat is required by rule 13 to keep clear, or
(c) both boats are OCS.”