GovWire

Completed preliminary assessment (PA) summary 2/24: Thames Kestrel

Synopsis

At 1340 on 19 July 2023, the Gravesend to Tilbury passenger ferry Thames Kestrel made contact with the brow of Gravesend Town Pier (Figure 1).

The impact resulted in damage to the vessels wheelhouse (Figure 2). None of the 35 passengers or two crew were injured and everyone disembarked safely.

Shortly after departing from Gravesend Town Pier, Thames Kestrels steering system locked at the full helm to starboard position after its skipper had executed a turn to starboard to give way to a merchant vessel underway in the channel. The skipper unsuccessfully attempted to correct the fault by switching to the alternative electronic steering system, so the crew then reverted to a manual steering method to manoeuvre Thames Kestrel back to Gravesend Town Pier. This involved a member of the crew standing aft and moving the tiller arm on the steering direction control system while the skipper conned the ferry from the wheelhouse. The skipper attempted to berth Thames Kestrel on to the piers pontoon but lost control of the ferry and contact was made with the brow on the pier. A pilot launch attended and helped berth the ferry alongside the pier to allow the passengers to disembark.

Thames Kestrels waterjet manoeuvring system had been overhauled and the hydraulic components replaced before the ferry entered service with Jetstream Tours Ltd in August 2022. The electronic control for the vessels manoeuvring system was as originally designed and fitted. A similar loss of control had occurred under the ferrys previous owners (MAIB report 6/2017) and the Maritime and Coastguard Agency (MCA) originally required an alternative steering system to be fitted; this modification was carried out by the vessels current owners, Jetstream Tours Ltd, and involved fitting a tiller arm to the waterjet directional control actuator. The tiller arm was moved via a series of pulleys and ropes by a crew member positioned at the vessels stern.

The MAIBs preliminary assessment identified that:

• The steering system failure was caused by the electronic steering control feedback potentiometer loosening due to vibration and releasing from its mounting and rotating, transmitting a false signal to the control system. The potentiometer was common to both electronic steering systems.

• The vessel made contact with the brow of the pier because the ferry took a wide turn towards the berth on approach to the pier and did not follow the expected parallel course.

• The skipper misjudged the high speed of approach and was unable to sufficiently slow the ferrys speed, resulting in it overshooting the berth and making contact with the brow of the pier.

• The skipper attempted to berth the vessel as usual despite the steering being operated in a reversionary mode. The skippers ability to focus on the berthing task and to execute the manoeuvre were hindered by the need to relay steering orders to the crew member at the aft of the vessel operating the manual steering. This resulted in the unusually wide turn and the speed misjudgement.

Actions taken

Following the accident, the vessels owner, Jetstream Tours Ltd has:

• Modified the securing arrangement of the electronic steering control feedback potentiometer on Thames Kestrel and its sister vessel using self-locking fasteners.

• Issued an instruction to its ferries skippers to manoeuvre to a place of safety and call for assistance before attempting to berth alongside while using the manual steering system.