In the diagram, the course is a twice around windward-leeward course. The same mark is used as the start mark, the leeward mark and the finishing mark. The race committee either uses a different boat for the start and finish or moves in between the start and finish. At position 5, Purple crosses the finishing line from the course side. According to the first part of the definition of finish, she has finished. The third exception applies because they continue to sail the course and do another lap. She crosses the line again at position 11. This time she finishes. This type of course setup used to be quite common. It can cause confusion and it involves moving the signal boat, so it is not used as frequently as it used to be.


In the second diagram, there is a leeward gate just above the start/finish line. Yellow has trouble getting her spinnaker down as she gets to the gate. While she is struggling to get the spinnaker down, she drifts through the finish line from the course side. She finally gets herself sorted out and starts to sail up wind to the next mark. She is continuing to sail the course and the third exception applies.


If you had asked me a few weeks ago for the meaning of “continuing the sail the course” I would have given just these two examples. I recently discovered that recently, World Sailing issued Case 148. It can be found in the latest edition of the case book https://d7qh6ksdplczd.cloudfront.net/sailing/wp-content/uploads/2023/02/28112609/Case-Book-for-2021-2024-with-2022-2023-Supplements.pdf World Sailing Cases are authoritative interpretations of the rules. This case says that a boat can cross the finishing line from the course side and then go back and correct other errors in sailing the course, not just the errors at the finishing line, as long as “her actions are consistent with continuing ‘to sail the course’” The cases describes a boat that after crossing the line for the first time “eased her mainsheet, luffed her sail and stopped for 30 seconds”. The cases conclude that these actions are not consistent with sailing the course, so the exception does not apply and this boat has finished and therefore it is too late to apply rule 28.2 and correct any errors in sailing the course. In the diagram above, where Blue slows down at position 4 and luffs at position 5, I would conclude that she was not continuing the sail the course. If she then discovers that she missed a mark, it is too late.