Applies only when the notice of race or sailing instructions say so. Judges on the water signal a rule 42 penalty with a sound, a yellow flag pointed at the boat and a hail.
Key points
P2 Escalating penalties
First penalty in the event: a Two-Turns Penalty (or disqualification without a hearing if not taken). Second: retire promptly, or be disqualified with no discard. Third and later: retire, with the disqualification non-excludable; fail to retire and you are disqualified from every race of the event with no discard, and the jury considers rule 69.
P3 Postponement, general recall or abandonment
The penalty is cancelled but still counts towards the number of penalties.
P4 Redress limitation
No redress for a judge's call unless the judge ignored a race committee signal or a class rule.
P5 Flags O and R
When class rules allow pumping, rocking and ooching above a set wind speed, flag O (before the warning signal, or at a mark after the start) means it is allowed; flag R means rule 42 as changed by the class rules applies again.