Thanks for the responses. But I need to clarify a few things.
Boat A is fetching the mark, however is not within the three boat length distance to the mark. Boat B cannot pass clear ahead of Boat A bow and has to tack. The tack is short and just below Boat A, but within three boat lengths of Boat A, probably closer to one to two boat lengths. Boat B does not want to under shoot the mark and has to sail high a close hauled coarse. Boat A is carrying more speed and will over take Boat B within seconds. Since Boat B needs to sail close hauled, she sails a higher coarse.
My take is Boat B needs to give room to Boat A or a least time to alter coarse to steer around Boat B because he tacked on a Starboard boat, however my take is Boat B wants to drive Boat A of his line to the mark, which would allow Boat B to round ahead of Boat A or create a penalty situation if Boat A does not respond.
Am I off base on thinking Boat B tacking on Boat A has to stay clear since Boat A had the ROW. It really depends on whether Boat B has finished its tack, if Boat A has to steer around Boat B isn't that a penalty since the Boat A has to alter coarse and was the starboard boat.
This happened really fast when boats are moving at 5-6 knots. There is a lot going on in a few seconds to create the situation.