I had an idea, so I made this.
It works pretty well.
It does not like very strong winds though.

Not knowing a lot about sailing craft, I can not say if this behaves in the right fashion or not.

It has nowhere near the performance of a modern sail craft, I know that much.
A 60mph wind will get you maybe 25mph speed, but the craft moves by wind alone, no hidden motors.

The 'sail' is a structural wing XML'd to be weightless and dragless, so that the movement of all that weight does not affect the boat.

The 'mast' is a floppy rotator hinge and the winch controls the sail.

Controls: VTOL up extends the 'rope' on the winch and that moves the sail.

Rudder control is as per aircraft.

The sail will move from one side to the other, depending on how the 'wind' is hitting it and how the boat is pointing.

It's possible that with a better hull shape that a sail craft using this method would work much better than this one.

Warning: Should be boring as poo, but I found it fun to mess with for a little while.