This one comes to me from an umpire at the ICSA Pacific Coast Team Racing Championship.
Approaching mark 1 (to be left to starboard), Dark Blue is nearly stationary. Her teammate, Light Blue, is approaching from behind with an opponent, Yellow, to windward. As they approach Dark Blue, Yellow hails for room. Light blue continues to point directly at Dark Blue's transom until Yellow is "hooked" to windward. Light Blue then bears down below Dark Blue, and Yellow is trapped to windward. Yellow protests. What should the call be?