Since the beginning of 2020, and during COVID-19, our Global Office Network received an increased number of instructions on Stern Tube damages, totalling 25 to date. The latest instruction was received by our new Singapore Office, with damage discovered at Unithai Shipyard (Thailand), being catastrophic to both aft ST bush and tailshaft (photos).
The nature and extent of damage varies in each case, sometimes limited to ST bush bearing metal wiping, or resulting in catastrophic failure during voyage/loss of propulsion with vessel needing towage to destination or port of refuge, arising to General Average expenditure when vessels are in laden condition. At COVID lockdown periods, limited availability of Shipyard Drydocking space, resulted in rapid deterioration of bush condition and aggravation of damage – a “force majeure” situation.
Investigation into the cause of failure in each case suggests that the ST bush wiping is usually gradual and Lub oil analysis records indicate that, in most cases, the periods until discovery of damage/failure are rather long, without necessarily triggering high-temperature alarms or involving sea water ingress / LO leakage.
