Abstract: This invention relates to apparatus for the control of a weight suspended from a vessel employing a pneumatic suspension system subject to heave action so as to maintain the pressure in the pneumatic system substantially constant during the heave of the vessel as the result of the wave action.

Abstract: The traveling block of the derrick mounted on a floating barge is connected in off-center relation with a load supporting motion compensator cylinder, the sheaves being located and strung asymmetrically with respect to the center line of the motion compensator cylinder. The crown block sheaves are rotatable on axes which are skewed to reduce fleet angle of the line. Different size sheaves are strung differently and different numbers of line runs are strung differently to equalize the forces about the center of gravity of the mass of the traveling block.

Abstract: A compensating apparatus is suspended from a divided crown block mounted on a derrick of a floating drilling barge, the compensating apparatus including a single cylinder extending vertically between and carrying divided travelling block sheaves on opposite sides thereof, with drawwork lines passing over the divided crown block sheaves and divided travelling block sheaves, and with the upper portion of the cylinder extending between such lines and adapted to move upwardly between the crown block sheaves without interference. A piston structure, forming part of the compensating apparatus, is slidable in the cylinder, being connected to a hook, or the like, from which a running string, such as a drilling string, is suspended extends into an underlying well bore, liquid under pressure in the cylinder acting on the piston structure to support part or all of the weight of the running string.