Picture this:
Two A'Classes flying in towards the windward mark both on Port. The windard A has a slight overlap so the leeward A' gives just enough mark room (no problems so far). However, there's a Dart 18 also on Port which was clear ahead at the 3 boat circle. The Leeward A' can scoot around the leeward side of the Dart quite happily but the windward A looks to be going right up their transom at quite a speed.
Does the Leeward A' have to give the windward A' extra room to round both the Mark and Dart ? Or should the windward A' looked ahead and decided to slow down and follow what was the leeward A' around the Dart and Mark?
Since the Dart was clear ahead at the zone, both A's are required to give her
mark room. See rule 18.2(b). This makes the Dart an
obstruction to both of them. See the definition of Obstruction. If the leeward A chooses to sail below the Dart, she must give the windward A room to sail below her also. See rule 19.2(b).
I hope that helps,
Eric
