A device for sealing a ship's propeller shaft between external water and a lubricating medium chamber is provided with a seal arrangement with multiple seals. At least one oil-filled seal chamber is disposed and comprises a supplying device from a tank via an input pipeline. In the input pipeline of the oil-filled seal chamber, a circulation pump is arranged between the tank and the seal chamber. The input pipeline is connected with the lower area of the seal chamber. And the upper area of the seal chamber comprises an exhaust pipeline leading to the tank.