As UK MAIB reports in its most recent Safety Digest, a passenger ferry completed loading and was preparing for departure.
The incident
Harbour control gave approval for the ferry to depart and advised there was no traffic to affect the outward passage. With all departure checks completed, the master instructed the crew to let go of the mooring lines.
At the same time, an inbound ferry was in the channel destined for the berth being vacated. Harbour control directed the inbound ferry to wait in the vicinity of the last starboard lateral buoy, east of the breakwater. The inbound ferry’s bridge team misinterpreted the message and continued their approach, thinking
they had just been asked to slow down. The ferry passed the lateral mark and turned towards the harbour entrance.
Unaware of any conflicting traffic, the outbound ferry cleared the berth and started making way; however, as it approached the breakwater the inbound ferry was spotted and the risk of collision immediately identified. The outbound ferry’s master urgently attempted to agree a suitable passing arrangement with the inbound ferry’s master over very high frequency (VHF) radio, but the situation remained unclear.
The outbound ferry’s master put the helm hard to starboard and applied full bow thruster power to starboard. The outbound ferry’s bow swung clear, but the stern was swinging to port towards the inbound ferry so the master stopped the bow thruster and applied port rudder to avoid collision. The ferries passed one another at about 50m.
Credit: UK MAIB
Lessons learned
- Communicate: Navigational and safety communications from ship-to-ship and ship-to-shore must be precise and clear to avoid confusion and error; the use of standard marine communication phrases can avoid ambiguity. In circumstances such as this, where there was a lack of clarity among both the ferries and harbour control, closed-loop communications can ensure that messages are received and, more importantly, understood. Having a receiver repeat back the relayed information allows the sender to confirm the understanding of the message and, if necessary, relay it again. In this case, it might have prompted the port controller to reassess the intentions of the inbound ferry.
- Equipment: The use of VHF radio for collision avoidance can be unhelpful and may even prove dangerous. In this instance, the radio communication delayed the manoeuvre and led to confusion between the bridge teams. Although it is useful in limited circumstances, VHF is not a collision-avoidance tool and must only be considered a navigation aid when it is appropriate to do so.
- Monitor: Maintaining a safe watch starts before the lines are let go. Monitoring the automatic identification system (AIS) and listening to VHF messages can provide an early indication of potentially conflicting traffic. It was established after the incident that both ferries were transmitting on AIS and it would therefore have been straightforward for the outbound ferry’s bridge team to plot the inbound ferry before getting underway.
- Action: The inbound ferry did not communicate to harbour control that they needed to maintain headway for steerage and the strong breeze would have made waiting or loitering at the lateral buoy difficult. Maintaining a higher speed to reduce drift is sometimes necessary; however, actions contrary to harbour control’s instructions should be communicated immediately to assess the impact on other traffic and maintain a shared mental model.
