That's a larger model, this is the earlier Saildrone Explorer mentioned in that video. The vessel they are launching is 72 feet long, this one is 23 feet. So not a model boat, but not large either.
Nice, I had seen the Explorer models a while back and rather liked the work they were doing, it's great to see they are progressing and making larger ones.
It's a self trimming wingsail. Its only purpose is to maintain the angle of attack of the main wing, much like how a horizontal stabilizer works on an airplane.
Personally I think it is something that is brilliant, and it is actually the primary feature that enables autonomous operation as a drone. There are no halyards or sheets, no ropes anywhere. All you have to do is maintain an angle of attack relative to the wind, and you have propulsion.
BTW, the founder holds the wind propulsion land speed record, and the wing design for this is an evolution of that design. When you're moving at 4 times the wind speed, no human can possibly keep up with the continuous trimming demands of a sail. This design does it perfectly, and at an overall reduction in total complexity.
That's a safety feature as much as it is an efficiency feature, it allows you to safely furl the blades when you are overspeeding, you can't rely on anything that isn't directly connected to the rotor base because it might be jammed, damaged, out of power or missing entirely. The blades governing themselves is the ideal, the linkage is there for synchronization and balance purposes only.
Probably wasn't clear above, I'm saying they weren't using a swashplate (most helicopters) they were using this little tiny tab attached to the rotor that could be controlled.
