A significant increase in stern tube-related damage claims in recent years.
The introduction of Environmentally Acceptable Lubricants (EAL) in 2013, the number of reported damages grew rapidly, says Cefor, and adds that this continues to be a source of great concern for its members because there is little evidence that the number of reported incidents is dropping.
Stern tube damages can result in loss of propulsion and the requirement for tug assistance. In most cases, stern tube damages will also require docking of the vessel to conduct the repair.
However, the Cefor members have also observed that damage to the stern tube bearings is often discovered in connection with a scheduled docking. While this does not create an immediate danger to the vessel and her crew, it will typically delay the vessel in dock and interfere with the shipyard’s docking plan of other vessels. In severe cases when the propeller shaft is found to be damaged, the repair time or, in the worst-case scenario, the delivery time of a new propeller shaft, may be significant.
A desire to raise awareness of the issue among shipowners and crews, as well as to encourage actions that can be taken to prevent or mitigate stern tube damage.
They also emphasise that operational failures to the stern tube system should be notified to the classification society, and that prolonged operation without assessment and guidance from the maker should be avoided in the event of increasing bearing temperature and/or water ingress into the system.