A 50,000 GT ro-ro vessel was conducting its loading operations in a European port, while the Navigation Officer had prepared the passage plan for the next port of call in central America. Before departure, the Master received weather routing for the passage which suggested a route over the Silver Bank and via the Windward Passage.
Following, the Navigation Officer scheduled the route in the ECDIS and on paper charts and found out that the minimum depth the vessel would encounter was at the Silver Bank where the water depth was 16 metres according to British Admiralty chart 3908.
The ship’s draft was 7.5 metres, meaning that a 16-metre water depth was consider acceptable according to the company’s ISM under keel clearance procedure, according to which there had to be a minimum of 20% under the keel clearance of the maximum draught.
It is highlighted that on the route planned by the Navigation Officer there was no specific mention of inadequately surveyed waters. The Navigation Officer did not consult the Admiralty Sailing Directions when preparing the passage plan.
The Master firstly checked the entire routing on the ECDIS and on the paper charts and then followed the route that was suggested by the weather routing company.
The passage was ‘quite’ over the Atlantic from Europe and the vessel maintained a speed of 13.5 knots. Yet, a bit later of entering the Silver Bank the vessel’s bow suddenly swung to starboard, which caused a list for about 3 to 5 seconds, with excessive vibration.
That’s when the OOW switched to hand steering. A couple of minutes later the vessel’s bow swung to starboard, but this time with less vibration.
The vessel’s bow swung a third time to starboard and listed for about 3 seconds, with vibrations. The vessel continued the voyage to the next port of call after carrying out a damage assessment.
The assessment showed that the forepeak tank and a water ballast tank had water ingress. All the fuel tanks were intact.
Following the incident, the vessel arrived at the destination port, discharged the cargo and carried out an in-water survey. It was found that the tanks had been punctured as the vessel had touched bottom.
Therefore, the vessel had to be repaired in dry-dock.
- The vessel had on board the Admiralty Sailing Directions NP 70, West Indies Pilot, where it is stated that Silver Bank has been inadequately surveyed and it is not advisable to attempt to cross it. The sailing directions had not been reviewed before or after making preparing the passage plan.
It is important to ensure that all reference literature is used when making a passage plan.
- The Club notes that it is crucial to perform a two-person check for critical operations such as a passage plan. It is more likely that another person will find a mistake rather than just carrying out your own double checking.
The ECDIS chart information is based on data from the paper charts. If the quality of the data in the paper charts is poor, then so will the data in the ECDIS charts cell be.