the Wymaroo named after Chris Wyman, US sailor from the 90's is quite similar to a Gu Screw, named after Mark Angulo, older brother of Josh.
It is a downwind rotation which is really a very downwind flat spin loop.
Best way to try is carve hard downwind, like starting a fast carve gybe but don't lay your rig down to low, just like bottom turning into a Gu screw, then once heading straight downwind keep carving but initate a jump off of your toes to your heels, swinging your body hard to continue the downwind rotation. You need to pull your rig across you a bit like a slam gybe position and then sheet in hard as the rig pulls through the wind without catching on the water, keeping alot of mast foot pressure to spin the board around and to land as dry as possible.
Ricardo started to do these again over the last few years in freestyle heats but not as good as the originals, check out older vids such as surface tension etc for some good examples.
I heard Colin Dixon uses the Wymaroo as a teaching stepping stone to help sailors learn to spin loop.