This seal assures waterproofing at the propeller shaft (a turning shaft.)Progress in industrial materials has enabled the development of new turning joint systems for the shaft. The principle is simple: two rings with a polished surface (a stainless steel and a graphite ring)rub against one another. One ring is attached to the propeller shaft with which it turns, the other is attached to the stern tube by neoprene, this ensures a constant pressure. The sea water acts as a lubricator for the two rings. It is therefore important that the stern tube is always full of water. For fast boats, on which the stern tube empties due to the vessel speed, there are models with water injection (ask us.)The rotary joint frees you from all the
maintenance problems associated with conventional systems (water in the bilge, retightening, setting it so tight it damages the shaft…)Ensure there is water present in the valve by simply loosening it slightly. Although it does require maintenance,one should check the joint regularly, notably the collar tightness and the free rotation of the mobile ring.