A power take-off device for use in a wave energy converter unit having a buoy includes a power take-off hull connectable to a mooring device, and connected to or connectable to the buoy, preferably by a link rope, and a power extracting device adapted to extract power as the buoy moves with the waves, by applying up to a predetermined maximum control force. A two-stage end-stop cushioning system comprises a first stage end-stop cushioning device having a first fluid cylinder adapted to apply an additional deceleration force on the device above the maximum control force, and a second stage end-stop cushioning device adapted to be extended like a spring in an end-stop operation after the first stage has been activated and when the power take-off force is higher than the above the maximum control force, to hold the buoy submerged through the crest of a large wave.