A payload control apparatus includes a spring-line a spring line actuating mechanism, a spring line flying sheave over which a load line can pass, and a spring line, wherein the spring line flying sheave can move into a position either where the flying sheave is spaced from and in non-contact with or contacting but non-path-altering in relation to the load line, further wherein the spring-line flying sheave can be moved into another position such that the flying sheave engages the load-line and alters its path length. Thus, when a marine surface vessel falls in a heave event that would otherwise cause the payload at the end of the load line to fall as well, the flying sheave will move to increase the path length causing a shortening of the path length, thereby preventing the payload from falling.