My question was how far do they have to go on port to be considered the non-right of way boat?
A tacking boat gives up right-of-way after she passes head-to-wind. See rule 13.
Speaking hypothetically, in the situation you describe, since boat 1 did not hail boat 3 for room to tack (rule 20.1), and boat 2 did not pass along boat 1's hail (rule 20.3), boat 3 was not obligated to respond to either under rule 20.2. Boat 3 was only required to avoid contact if possible (rule 14). Boats 1 and 2 were required to keep clear of 3 (rule 10). If boat 3 needed to take action to avoid contact with boat 1 and/or boat 2, then boat 1 and/or boat 2 would have broken rule 10.
