Sea water seal without oil lubrication for pods

A sealing device for a propeller shaft of a marine vehicle propulsion unit, comprising:

• a set of sealing lips being (i) located within a movable housing;
• (ii) axially offset relative to one another and (iii) arranged for contact with a surface along a length of the propeller shaft, the set of sealing lips including, in an order from an inner space of the movable housing toward a space outside of the movable housing, a first sealing lip, a second sealing lip, a third sealing lip, a fourth sealing lip, and a fifth sealing lip;
• wherein the first sealing lip, the third sealing lip, the fourth sealing lip, and the fifth sealing lip of the set of sealing lips are axially angled toward a space outside of the movable housing, and the second sealing lip of the set of sealing lips is axially angled toward an inner space of the movable housing;
• a receiving space for a hydraulic fluid, the receiving space being defined between the first sealing lip and the second sealing lip of the set of sealing lips;
• at least one buffer space being axially offset with respect to the receiving space and defined between two adjacent sealing lips of the set of sealing lips other than the first sealing lip and the second sealing lip;
• a feeding device configured to supply the at least one buffer space with a buffer fluid;
• a sampling circuit configured to sample buffer fluid contained in the at least one buffer space;
• and
• a monitoring device fluidically connected to the at least one buffer space and configured to check parameters of the buffer fluid sampled by the sampling circuit contained in the at least one buffer space.