Is it not more correct to say that the zone is now three boat lengths, but that this may be changed in the sailing instructions to 2 or 4 boat lengths……….?
I would suggest that the rules are used as written i.e 3 boat lengths, as I would suspect that most clubs will not change the rule, particularly in mixed fleet racing. It may create confusion if folks get used to one size zone in club racing and another one at a limited number of circuit events and the nationals. However, if most clubs choose to change the zone to 2 or 4 boat lengths, then it would be sensible for the class to do the same for its flagship events……
Just a thought……..