The scenarios below will be encountered by sailors racing in waters where there are multiple divisions of one club racing eg most sailing/yacht clubs, and where more than one club races at the same time on the same water eg most Saturday afternoons on most large metropolitan harbours and sometimes lakes or rivers. They address the fundamental question of whether or not the RRS apply between two boats one of which may be overtaking the other.
Consider this Original Scenario: If boat O(vertaking) from club N(orth) which races under the RRS is sailing in Race 1 and is clear astern of Boat A(head) and establishes an overlap to leeward from clear astern less than 2 boat lengths (of Boat O) from boat A which is also sailing in Race 1 from club N, Boat O is entitled to sail up to her proper course. If the overlap is established by O more than 2 boat lengths to leeward of A, then O can sail up past her proper course and right up to luffing to head to wind even if it forces A to sail above her proper course. Hopefully we are all agreed so far.
What if we change the Original Scenario to Scenario 2 so that boat A is sailing in Race 2 of Club N, not race 1? Do the RRS still apply, or do you have to revert to ColRegs and in particular to Rule 13? Is there anything needed in the sailing instructions to require the RRS to apply between boats racing in different races at the same club at overlapping times but possibly sailing different courses but with some legs being part of both boats' courses?
What if we change the Original Scenario to Scenario 3 so that Boat A is sailing in a race of Club S(outh) instead of Club N(orth)? Do the RRS still apply, or do you have to revert to ColRegs and in particular to Rule 13?
And of course if Boat A is sailing but not racing then we racing in boat O are forced to comply with the ColRegs as Boat A is not sailing under the RRS and so we need to consider whether we are approaching from more than or less than 22.5 degs aft of the beam of boat A .