Abstract: An improved rig assist compensation system is provided, comprising a motion compensation unit operatively connected to a semi-submersible rig platform having a blow-out prevention (BOP) stack; a hydraulic workover (HWO) jack rotatably affixed above the BOP stack, wherein the HWO hack includes a through-rotary portion, and a stationary portion; and a hydraulic motion compensator unit, positioned between the HWO jack and the BOP stack. The motion compensator unit comprises a base frame having a plurality of base cylinders; an upper frame having a plurality of mating upper cylinders to engage the base cylinders in telescoping fashion, wherein the base frame and the upper frame are slidably connected, and are movable from an extended position and a retracted position.