Situation 1
After a boat starts as per the definition, she touches the starting mark.

Question
Did the boat break rule 31?

Answer
Yes.
While racing but before starting, a boat shall not touch a starting mark. From the moment the boat starts, the starting mark begins the leg of the course on which she is sailing and she shall not touch it.

Situation 2
A boat sailing in the direction of the finishing line, overstands the mark of the finishing line, bears away and touches the mark. After she passes the mark, she luffs and finishes.

Question
Did the boat break rule 31?

Answer
Yes.
While the boat is sailing on the last leg and until she finishes, the finishing mark ends the leg from the previous mark to the finish and she shall not touch it. After she finishes but while still racing, a boat shall not touch a finishing mark.

Situation 3
A boat sailing from the course side in the direction of the finishing line, touches the mark of the finishing line, and takes a penalty under rule 44.2. After taking the penalty she crosses the finishing line from the course side again.

Question
Did the boat break rule 31?

Answer
Yes.
See situation 2. However, by taking a penalty under rule 44.2 she takes an appropriate penalty for her breach.

Situation 4
A boat sailing in the direction of the finishing line, overstands the finishing mark, bears away and touches the mark. Before finishing, she realizes she made an error under rule 28.2 by not rounding the last mark. The boat corrects this error and finishes.

Question
Did this boat break rule 31?

Answer
Yes.
While sailing towards the finishing line, the boat was sailing on the finishing leg. See situation 2. The finishing mark ceases to be a mark that begins, bounds or ends a leg of the course on which the boat is sailing, from the moment the boat realizes that she must correct an error under rule 28.2. See World Sailing Case 126.