tve has it right. Well, technically, it is a gybe when going downwind, but is a similar maneuver. Will take you across the face of the waves.
Can't quite see the point when using a surfski.
For sea kayaking, the idea is to conserve energy on long paddles. So, small sail/wing, small boost for a long paddle to give you a bit of a rest - but not expected to give a really high speed.