It's all about expectations... what does the NOR say?
If it doesn't ... perhaps the OA should resolve the class splits now and announce them before you get in the car and drive!
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Put in the NOR... or have the OA make their best guess at attendance, declare the class splits and let the racers know ahead of time.
I disagree. In an open invitational event such as this, there is no way the Organizing Authority can know ahead of time what boats will attend. The only reasonable course is to declare class break-out at the event. Furthermore, Race Committee is free under the rules to start multiple classes together. It wouldn't make sense to declare separate starts in the NOR.
Good Race Committees understand that their job is to serve the sailors. They are happy to provide separate or combined starts - whichever the competitors prefer. They do not dictate the racing format ex cathedra. That said, it is our responsibility as racers to tell RC our preferences. That's really why I wanted to have this discussion - so we could form our opinions in advance and be ready with them upon arrival.
When I am PRO for an event, I usually seek our "fleet captains" and ask them what their class members would like. RC wants input, and sailors want to be heard. I suggest each design decide amongst themselves what they would like, and send a representative to tell Race Committee on their behalf - preferably well before the competitors' meeting. Good, open communication can only improve the event.
Regards,
Eric