Here is a picture of the oil rig being towed in circles by the Pacific Champion. There is a little white dot just below the rig to the right, which is a sail boat, and seen through binoculars gives a good appreciation of the size of the rig.

If you go to
Marine Traffic and click on the turquoise ship off the southwest coast, heading approximately 255 degrees, then click on "show vessel's track" you can see it's just going in circles.
Not that this explains any of the mystery!