Lessons learned: Never rely on a single navigation appliance

At the time of the handover, the vessel had started a slow turn to port to follow the planned route. Several alarms were sounding, warning of a fault in the GPS receiver. This caused the navigation equipment to lose its positioning signal. Although the GPS was lost, the ECDIS and one of the radar units continued to estimate the vessel’s position using dead reckoning (DR).

The officer being relieved was aware that the GPS receiver had, at that time, lost its positioning signal, but noticed that the other GPS receiver was operational. He had experienced similar problems previously, and assumed that the relieving officer was also aware of the cause of the alarm and what actions to take to restore the GPS receiver if the positioning signal was not restored automatically. However, he did not confirm this with the relieving officer before leaving the bridge. Over a ten-minute period, the alarm signals were repeated on several of the navigation systems but after acknowledgement were silent. No further action was taken.

As the vessel came onto a course of 010°, the vessel’s true drift of two to three degrees to port of the course was not showing. Instead, the ECDIS showed that the vessel was sailing with a drift of two degrees to starboard, as it was on DR mode. This meant that the vessel was gradually moving to the west of the planned route. The deviation between the planned route and the actual route is shown on the chart overleaf. The OOW was oblivious of this variation because his attention was exclusively on the ECDIS display.

At 05:13 the vessel passed on the wrong side of an eastern cardinal mark that marks a shoal. The first grounding took place at this time. As the vessel passed over the shallow area, its speed decreased from 17 knots to 9 knots and there were strong vibrations, which continued for around 20 seconds. The chief officer, now on the bridge, observed that the X-band radar was missing a GPS signal and the OOW responded that this issue had persisted since the watch change. Once the vessel had passed the shoal and entered deeper water, speed increased again to 17 knots. The crew made no adjustments to the engine controls during the grounding because they did not realise they were off track and had touched bottom.

The Master, having felt the vibrations, came to the bridge. When he arrived, the vibrations had stopped; the OOW was unperturbed and the Master’s initial concerns were assuaged. The Master asked the bridge crew what had happened, but he did not receive an explanation for the vibrations. He checked the vessel’s position on the ECDIS, which showed that the vessel was following the planned route. The S-band radar also showed the DR calculated position, albeit with the position indicated in a different colour and the note ‘Dead Reckoned’. However, the radar image itself was not affected by the error.

At this point, the Master took over responsibility for the navigation and preparations for arrival began. The crew members on the bridge discussed whether the vessel had run over something, or if there were other possible causes for the vibrations. The bridge called the engine room to ensure that there was no problem with the engines. The response was that everything was in order.

Engine personnel then called back and informed the bridge that an overfill alarm had been activated in several bunker tanks and a level alarm had been activated in void tanks. The chief engineer called in extra engineering personnel to conduct tank soundings.

The Master engaged hand steering and ordered a heading of 345°, intending to steer the vessel towards the fairway of the arrival port. The ECDIS was still operating on DR and indicated that the vessel was following the planned route. However, the actual position was substantially further to the north-west, and the new heading took the vessel towards shallow water. Nobody on the bridge had double checked the position using other instruments.

When the vessel entered shallower water, the vessel speed decreased and a second grounding occurred at 05:24, with strong vibrations again occurring. The vibrations ceased when the vessel came to a stop, but the bridge team were still unaware that the vessel had grounded. The engine controls were reduced to slow and the engine room crew assured the bridge team that the engines were functioning normally. The Master decided to continue the voyage into port, so he increased the engine control, but the speed remained at zero. He interpreted this as the vessel having lost propulsion, but the chief engineer assured him that the engine was functioning as expected.

On the vessel’s bridge there was confusion about what had happened. The ECDIS showed that the vessel was in water 30m deep and drifting at half a knot in an easterly direction. The crew were still unaware that the vessel had run aground.

The Master called the coastal Joint Rescue Coordination Centre (JRCC) to inform them of the situation. The JRCC operator checked the vessel’s AIS track and realised there was an error. He informed the Master of the vessel’s true position. After a second call, the Master checked and found they were truly aground and not in deep water.

Passengers were then evacuated from the vessel. The salvage operation lasted 11 days and included a third grounding before it was successful. Heavy fuel oil had escaped from the vessel and the environmental response was a protracted, complicated affair involving several organisations.