Vessel ran aground following error on chart

What happened

A vessel ran aground whilst leaving a channel on the approach to a port. The vessel was making around 4.5 knots, and grounded by the stern in the right side of the channel. At the moment of grounding, the echo sounder was indicating a depth of 3.5 metres. Whilst leaving the channel, the vessel caught a small sand hill that had not been charted.

What went wrong? What were the causes?

During the investigation process, the channel navigational chart was carefully checked and errors were found. There were also indications that a buoy had shifted 5m due to the length of the chain anchoring the buoy.

What lessons were learned?

• Closer control of the water depth indication and echo-sounder information was required. Officers need to be more aware of the location and accuracy of the vessel’s fitted echo-sounder and its limitations in shallow water;
• Suspected errors in navigational marks should be reported to Port Authorities, and any changes reported should be marked on charts.

What actions were taken?

• Management were to approach the appropriate authorities with the findings from the company investigation and communicate updates to relevant vessels. The responsible authorities were to update the channel navigation chart and consider adjusting the length of the chain on the buoy;
• Ensure that deck officers are fully aware of the importance of constantly monitoring the vessel’s draft and echo sounder whilst passing through a channel;
• Passage planning should be from berth to berth. When making any passage plan, it is of absolute necessity to ensure there is safe navigable water throughout the route to be taken. Any areas of concern should be indicated on the chart so that all officers of the watch are aware of any potential issues.

Two tugs were provided to recover the vessel from the grounding. The Captain and Chief Engineer conducted a visual inspection of the hull and several internal compartments to confirm that the vessel’s seaworthiness was not affected. A diving inspection was carried out and confirmed that around two square metres of coating were affected, but there was no severe damage to the hull.

Members may wish to refer to the following incident from the UK Marine Accident Investigation Branch (MAIB):

• Grounding and flooding of ferry – complacency