Abstract: A seat and foot rest assembly to convert a surf board or sail board into a kayak type paddling craft. The assembly comprises a chassis, connectors to easily secure said chassis to the top wall of the water buoyant board, a seat secured to the rear portion of the chassis and a foot rest adjustably mounted on the front section of the chassis. The connectors include suction cups and board encircling straps or screws to be screwed within screw inserts carried by the board top wall. The conversion kit can easily be detached to allow the user to use the board in its original configuration. An optional steering mechanism is provided for more precise directional control of the craft. The steering mechanism includes a stern mounted rudder and a control stick operable by the user's feet and connected to the rudder by adjustable cables.