I don't know Matt. To me, it looks like the boat flying the chute was on starboard (look at the position of the whisker pole), which would make him the ROW vessel.
Spinnaker pole is on the port side - making that the windward side = port tack. The boom is on the starboard side = port tack. If you blow the photo up, you can see the spin sheet crossing the front of the mast - so there wasn't an accidental jibe during the collision (it's hard to tell if the pole is pinned to the forestay or just sticking out to port).
The downwind boat is on port tack.