After all boats had finished a race, the race committee realised that a mark had drifted out of position during the race. The race committee decided that, as a result of the drifting mark, the race was unfair for some boats.

May the race committee abandon the race after all boats have finished?

Yes, see rule 32.1.

However, after one or more boats have finished, the race committee should make every effort to ‘save’ the race, if necessary by requesting redress on behalf of all affected boats. The RC should only abandon a race if, after considering the consequences, it is satisfied that this is the fairest arrangement for all boats in the race or series.

If the answer is yes, how shall the race committee signal that the race is abandoned?

The race committee should post a notice about its decision. This may include the reasons for the decision.

If the boats are still in the racing area waiting for a further race when the race committee decides to abandon a completed race, the race committee may also display flag L from the race committee vessel and attempt to notify competitors afloat.

Displaying flag N is not suitable for abandoning a race that has been completed, as its meaning presupposes that the race is abandoned while it is in progress.