Abstract: In some aspects, an in-line passive heave compensator system includes a damper actuator, a fluid vessel, and a hydraulic manifold. The damper actuator extends and retracts in response to an external dynamic load, and the fluid vessel transfers hydraulic fluid between itself and the damper actuator (e.g., back and forth) as the damper actuator extends and retracts. The hydraulic manifold provides the channel of fluid transfer between the damper actuator and the fluid vessel. The hydraulic manifold includes an extension flow control device in an extension fluid path between the damper actuator and the fluid vessel. The extension fluid path receives fluid flow only during extension of the damper actuator. The hydraulic manifold includes a retraction flow control device in a retraction flow path between the damper actuator and the fluid vessel. The retraction flow path receives fluid flow only during the retraction of the damper actuator.