A coupling unit device for unloading of a ship, where the coupling unit comprises a hull and is arranged to be connected to the ship by means of a connecting element wherein the coupling unit is provided with an evaporator for liquefied natural gas (LNG) and the required pipe elements for transporting liquefied natural gas from the ship to the evaporator, as well as the required pipe elements for transporting the evaporated gas from the evaporator to a pipe for onward transport. The coupling unit is free-floating and is arranged to maneuver itself to the ship during the connection and disconnection from the ship by means of its own propulsion machinery.