At the Delta Lloyd Regatta I was spending a day on the water doing rule 42 work with Chris Atkins, one of the members of the Rule 18 working party. Together with three other persons he worked on the changes we will all find in our rule books next year.
In between races, we talked about these changes. I asked him specifically about the background for changing the two boat-length zone into three and the choice the OA or RC could make, to decrease this back to two or increase to four. Wouldn't this create confusion for sailors encountering different zones at different regattas?
First of all he explained to me the reason for the increase to three-length zone. In the new rule, the current "about to round" part of rule 18.1 is deleted. That part has always been a source for discussion and confusion. No longer!
Only when you enter the zone, rule 18 will begin to apply.
The working party concluded - as we all do with the current rule - that two lengths was a too small an area for that. Spinnakers are lowered and course is adjusted before entering the two lengths zone. Most boats are already busy with the rounding well before. Without the "about to round" part of the rule, the zone could not stay two lengths. He stressed that in most classes, three lengths should work on the water the same as the current rule, with the added bonus that the 'border' for rule 18 was now fixed.
There are classes and circumstances that the three-length zone may be too large or too small. The working party wanted to give race committees the ability to deal with that. In the current rule book two-lengths is in the definitions and cannot be changed. In the new rule it is specifically allowed to change it in the sailing instructions. But the working party wanted it to be an exception, only to be done for very specific classes or circumstances.
For example on a small lake with slow(er) boats, or in team racing, where three would be too much. Gates could be 5-6 boat lengths instead of 7 or 8, marks could be closer to shore etc. etc.
Or for multihulls and yacht racing (those very fast boats) the zone can be increased to four, to give more time to do a proper rounding, without having to drop that huge spinnaker in five seconds. But only in those very special cases.
The intention is to stick to the three-length zone for all classes and all regattas, as much as possible.
Class Associations, Race Committees and Organizers, who have a say in what is written in the Sailing Instructions, should only change the three length-zone, if they are absolutely convinced that it is necessary. For sailors it is hard enough to judge the distance, without the added difficulty of having to change from one regatta to the next.
I suspect whenever ISAF has any say in it - for graded events at least - the requirement will be to leave the three-length zone intact.