Mooring rope caught in stern thruster

A vessel was preparing to depart with a pilot onboard. Local traffic control instructed the Pilot that the vessel must remain alongside until another vessel departed and passed astern, and that the vessel was not permitted to use thrusters until the passing vessel was clear.

The Pilot advised the Master to “start with the stern ropes first,” which the Master relayed to the deck crew. This wording was interpreted as an action command, rather than an instruction to prepare, resulting in the unintended release of both stern lines by the deck crew. Critically, the aft spring was already taken onboard, unnoticed from the bridge due to the aft capstan winch location and blind spot. Although the forward spring remained in place, it was later assessed that it had not been properly adjusted / tensioned, allowing the vessel to surge ahead when the stern lines were released.

With only forward lines restraining the vessel and a significant river current acting as a wedge between the stern and the quay, the vessel began moving toward another berth. The Master applied astern propulsion and lateral thrusters to regain control. During this manoeuvring, deck crew reported that a rope had gone under the stern.

• Miscommunication: An ambiguous mooring instruction was interpreted as an immediate release order, leading to premature letting go of stern lines.
• Loss of situational awareness due to blind spots and no verification of spring-line status.
• Bridge Resource Management (BRM) failure, including the lack of closed loop communication and assumption of shared understanding.
• Overreliance on informal phraseology, instead of standardised mooring commands.