How do race time limits work, and when must I abandon for lack of a finisher?

Under rule 35, if one boat sails the course within the time limit for that race (if any), all boats that finish are scored according to their finishing places, unless the race is abandoned. If no boat sails the course within the race time limit, the race committee must abandon the race.

Rule 90.3(a) adds that a race is scored if it is not abandoned and one boat sails the course within the race time limit, even if she retires after finishing or is disqualified.

Also, after one boat has sailed the course within the time limit, if any, the race committee must not abandon the race without considering the consequences for all boats in the race or series (rule 32.1).

Source: Racing Rules of Sailing 2025-2028, rules 32.1, 35 and 90.3(a), https://cdn.revolutionise.com.au/site/ofeyzh6cn3tumfga.pdf