Shaft seals are essential to the reliability and environmental compliance of a vessels primary shafting. They sit either on the forward end or both the aft and forward ends of a Stern tube on the conventional shafting of a vessel. They can also be found on Thruster or podded type propulsion units. These seals are very similar to the aft seals found on conventional Stern tube arrangements. ATZ with our partner Aegir Marine have the parts, service and experience to overhaul most shaft seal types.
For the purpose of this section we will discuss shafts seals as found on Stern tubes as the principles can be applied to seals in other propulsion arrangements
Two main types of Sterntube configuration exist, which are:
In both case they are normally supported by an emergency inflatable seal as should failure occur, this is only a single barrier system
The importance of reliable operation and refurbishment of marine shaft seals cannot be underestimated. Through failure comes the possibility of:
Routine maintenance and refurbishment of marine shaft seals is carried out at 5 yearly intervals and usually consists of:
ATZ with our partner Aegir Marine have extensive experience with most shaft seals types are in position to meet your parts and service needs for stern tubes, thrusters, pods and more. We use specialist dive teams for underwater fault finding, refurbishment and repair of outboard seals.
If within the limits of the maker, plan for overhaul at the next opportunity. If leakage is beyond these limits are starting to test the limits of the bilge pumps then the shaft should be stopped, locked in position and the emergency inflatable seal activated. Make plans for immediate refurbishment, repair and investigation.
Yes. Make sure that your new lip seals are supplied split and that the specialist tooling and experience for bonding is brought in to carry out the job.
If the seal header tank oil levels are rising, then the lip seals either side of the Sterntube volume are leaking. This should be monitored, and plans made for repair.
If the seal header tank oil levels are not rising, then either there is a system pipework leak (trace and rectify) or oil is leaking outboard of the vessel. This should be investigated immediately with a visual check at the eft end of the vessel and a dive inspection if required.
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