Lessons learned: Safe vessel interfaces depend on agreed methods and clear communication

What happened

The vessel was preparing to connect a tow wire to pull back a tanker. It was manoeuvring astern and was approximately 10 metres from the tanker’s stern, ready to receive a heaving line and messenger line. The tanker was stopped on dynamic positioning, with its bow facing the prevailing current and weather.

The agreed arrangement was straightforward: the bridge crew of the vessel would communicate by VHF when it was ready to receive the heaving line. The heaving line was also the approved method for passing the messenger rope. That agreed sequence was not followed.

Without prior warning or agreement from the other vessel, the tanker’s deck crew discharged an LTA. The apparatus split into two parts during firing. One part of the rocket struck the upper spooling winch, while the line detached and returned to the tanker’s deck.

Nobody was injured and neither vessel was damaged. However, the event occurred while the vessels were in close proximity and during an operation involving lines, winches and personnel on deck. The absence of an actual injury should therefore not obscure the significance of the near miss.

IMCA identified ineffective communication, failure to follow the agreed procedure, inadequate control of the vessel-to-vessel interface and concerns over the LTA’s maintenance or handling as contributing factors.

What went wrong

The central weakness was not simply that an LTA was used. It was that the method of transfer changed without the other vessel knowing or agreeing to the change.

The operation already had an established method: the vessel would confirm readiness by VHF and the tanker would then use a heaving line. That arrangement created a shared expectation about what would happen next. When the LTA was fired without notification, that shared understanding disappeared.

This matters particularly during close-quarters operations. Personnel on the receiving vessel may be positioning themselves, preparing equipment or establishing safe working positions on the assumption that the agreed method will be used. Introducing a projectile or rocket unexpectedly changes the hazard picture immediately.

The event also demonstrates why procedures between two vessels cannot depend solely on each vessel having its own SMS arrangements. Where an operation crosses the boundary between two organisations, there needs to be a practical interface mechanism that establishes who communicates, who authorises the next step, which method will be used and what happens if the plan changes.

IMCA also reported that the LTA malfunctioned, with the apparatus splitting into two parts. The Safety Flash attributes this to inadequate maintenance or improper handling.

The big picture

This near miss is a useful reminder that the interface between two competent crews can itself become a safety-critical system.

Both vessels may have sound procedures, experienced personnel and appropriate equipment, yet the operation can still become unsafe if the two sides do not have the same understanding of the plan. The issue is therefore broader than individual compliance. It concerns how the organisations establish a shared operating picture before work starts.

Similar lessons have appeared in other marine operations. SAFETY4SEA previously reported an IMCA case in which an intended method of handling a tow wire was not clearly communicated or understood between members of the working team, resulting in a line-of-fire incident.

There is also a recurring lesson around changes to an agreed plan. IMCA has highlighted cases where an alternative method was introduced during an operation without adequate reassessment or a toolbox discussion.

The practical implication is important: a pre-job plan is not complete merely because it exists on paper. The people actually conducting the operation need to understand it, and there must be a mechanism for stopping and resetting the operation when circumstances or methods change.

What could have prevented the incident?

A more robust vessel-interface arrangement would make the agreed transfer method explicit before the operation begins and require confirmation by both sides before any line is sent.

For operators and crews, useful safeguards include:

• Use a joint pre-transfer checklist. Both vessels should confirm the intended method, communication channel, sequence of actions and responsibilities before coming into the transfer position.
• Define the trigger for each action. “Ready” should have a common meaning. The receiving vessel should clearly communicate when personnel and equipment are ready before the transfer begins.
• Control changes to the plan. If a heaving line cannot be used and another method is proposed, the operation should pause until both vessels agree on the revised method and any additional hazards have been considered.
• Treat line-throwing equipment as safety-critical equipment. Maintenance status, expiry or service dates, condition and correct handling should be verified before use.
• Use Stop Work Authority. An unexpected action during a close-quarters operation should be sufficient reason for personnel to intervene, stop the operation and establish what has changed.
• Verify the interface, not just the individual procedures. The superintendent, Master or person responsible for the operation should ask whether the two vessels’ procedures actually work together in practice.

These principles are consistent with wider industry experience. SAFETY4SEA has previously highlighted that Stop Work Authority is effective only when personnel understand that they can intervene when an unsafe condition develops, rather than treating it as a policy that exists only in the SMS.