20  Starting Errors; Penalty Turns; Moving Astern
20.1  A boat sailing towards the pre-start side of the starting line or its extensions after her starting signal to start or to comply with rule 30.1 shall keep clear of a boat not doing so until she is completely on the pre-start side.
20.2  A boat making a penalty turn shall keep clear of one that is not.
20.3  A boat moving astern by backing a sail shall keep clear of one that is not.