Patent ID: 7887066

Claim:
A device for use in activity on a snow-covered surface or on a water surface, comprising a) a bottom board for contact with the surface, said bottom board having a longitudinally flat or slightly concavely curved central portion which extends from a curved front portion to a rear portion of the board, said bottom board further comprising side faces on each side of the central portion that are higher than the central portion, and yet further comprising longitudinal steering ribs or grooves arranged on the underside of the central portion, said steering ribs or grooves extending from the curved front portion to the rear portion; and b) a top board attached to the bottom board, said top board and the top board being joined together along their edges so as to define a hollow space between them, said top board comprising depressions along its sides adapted for receiving the legs of a user when in a riding position; wherein: c) the top board comprises a central region having an elongate, trough-shaped depression in which there is secured an airtight bag that is adapted to the depression, said airtight bag adapted to function as a seat for the user; d) the central portion of the bottom board has longitudinal edges comprising auxiliary steering ribs arranged on each side of the central portion, said auxiliary steering ribs being shorter than the longitudinal steering ribs or grooves, said auxiliary steering ribs being flattened towards the forward and rear end areas of the central portion; e) the side faces of the bottom board are flat, and are angled slightly upwards towards a substantially curved face part which forms a transition from the bottom board to the top board, each of said side faces being equipped with a steering runner projecting at an angle from the side face; and f) the device, at its front end is equipped with fastening means for a towing line or rope.