STERN TUBE BERINGS FAILURE :
While sailing, stern tube system oil level was found to be slowly reducing. After checks it was found that the aft seal was leaking and oil was being lost to sea.
Temporary measures were taken to prevent the oil loss and also the pollution. A lub oil drum was rigged up to act as header tank. The height of the drum could be adjusted using a chain block, depending on the requirement as the swell changes outside. This helped in solving the pollution and loss of oil problems, temporarily.
The ship was taken to dry dock after the cargo work finished, and the tail shaft was removed in the dry dock. Both forward and aft stern tube bearings were found wiped out and pieces this wiped bearing metal had found their way to the seals, damaging them and causing the oil to leak.
The material of the bearing was found to be too much lead based, which was unable to carry the load. Hence the tin based bearing material was renewed, which has the higher load bearing capacity
(Mr K R V Kumar, C/E, REO on 20.08.07)