Stability:
Case Study 2
Vessel Type: Feeder Container
Trading Area: Far East
Case No: 32771
The Incident:
This incident took place on a 25 year old 370 teu feeder container ship. Shortly before arriving
at the pilot station, an unexplained port list suddenly developed. The list was corrected and“sounding round” showed there to be about 100 cm of water in her hold.
Until berthed, the vessel had flopped one way or another on a number of occasions, each time corrected by moving ballast. Alongside she lay with a 15° list against the quay. The Chief Officer carried out an assessment of the stability and deemed the vessel to be unstable. The port authority subsequently refused to give permission for cargo operations to commence until the vessel was upright, the cause of the listing was determined and stability was confirmed by the Classification Society.
Efforts to pump out the hold bilge were thwarted by choked suctions. The services of a local
salvage company were engaged to pump out the hold and remove the top tier of containers in
order to regain positive stability. The ballast tanks were closely monitored during this operation
and it became apparent that water from two ballast tanks was entering the hold. The stability
calculations were reworked and showed the vessel to have positive stability. This was later
confirmed by the Classification Society.
Permission for cargo operations to commence was given nearly three days after the vessel’s arrival at the port.
The Cause:
The incident was caused by free water in the cargo hold. Choked hold bilge suctions
prevented the water being pumped out by the ship’s staff.Investigations showed that the vessel had sustained two fractures in the tank top. These were
believed to have been caused by the heavy landing of containers during loading. The
problem was further exacerbated by the fact that the heeling tank filling pipe had corroded
through. Ironically therefore, ballast water used to correct the list increased the leakage into
the hold, aggravating the problem.
Observations:
The Master was criticised for not conducting a more thorough investigation at the time of the
initial listing.
A regular systematic daily sounding programme is a well established procedure of good seamanship and would give an early indication of any problem. It would do away with the need to engage in the dangerous practice of entering enclosed spaces to visually check the hold. The difficulties in pumping out the hold once the water had entered were reportedly due to the suctions being choked with debris. This highlights the need for the holds to be kept free of rubbish and the regular proving of the pumping arrangements. The provision of a hold bilge alarm would have given a very early indication of the water entering the hold. The original erroneous stability calculation was a major contributing factor to the delay suffered by the vessel. This should have been carried out prior to leaving the load port.Third party calculations can not be relied upon.
The base of cell guides which carry the brunt of heavy container movements, should be inspected on a regular basis so that corrosion and weakness can be detected at an early stage.
The Financial Cost:
The total claim is expected to be in the region of US$75,000 to US$100,000.
