Sailing close-hauled upwind is the point of sail most easily balanced.

This photo shows me upwind in a gentle breeze.

The wheel is held up just a fraction to push the boat downwind and held there by shock cord. Meanwhile, the mainsail is close-hauled but then eased a fraction. The rudder is not steering enough to overcome the main wanting to push the boat up until the main approaches luffing. Then, as the main loses power, the rudder takes over until the main catches more wind and pushes her up again.

A continuous series of S bends results. The finer the trim, the shallower the S bends, For this to work, the main needs to luff just before the jib would, hence the main is eased a fraction.

This boat will sail indefinitely like this. Until it hits the shore. Don’t fall overboard – the boat will sail away from you.