It was a system called Windhunter which was fitted to my previous boat. It seemed a good idea, apart from the slight inconvenience of the towed generator, but in practice proved almost impossible to set up properly in self-steering mode. It was extremely sensitive to any change in wind, current, or the price of fish, and was frustrating to say the least. All the other users I spoke to found much the same thing, although a couple of them found it OK for very extended trips, eg Pacific crossings.
Was a good, if expensive, way for battery charging, though.
That was it. Another good idea launched on an unsuspecting public before the development was done.
I got caught by Cufo-Foil, a stuck on sheathing/anti fouling. Damn good idea, but the glue didn't work. Several radar reflectors that didn't and self heating soup that wouldn't..
I remain a hopeful optimist .