This report summarizes an incident investigated by the National Transportation Safety Board (NTSB) involving a collision between a multi-purpose cargo vessel and a moored bulk carrier in the Houston Ship Channel, Texas, on August 25, 2023. The event resulted in significant vessel damage but no injuries or pollution.
What Happened
While departing from a terminal on the Houston Ship Channel, a multi-purpose cargo vessel lost primary steering control. The vessel was underway under pilotage, with normal steering verified before departure. During transfer of steering control from the port bridge wing to the main bridge console, the rudder unexpectedly moved hard to port instead of responding to helm commands.
Attempts to regain steering through the primary system failed, prompting the master to activate the emergency override mode. Despite regaining limited rudder control, the vessel could not avoid striking a moored bulk carrier at the nearby terminal. The collision caused hull damage to both vessels, estimated at approximately $1.175 million. There were no injuries or pollution.
Why It Happened
The NTSB determined that the primary cause of the collision was a failure in the vessel’s steering control system. A malfunctioning component—specifically the bridge wing non-follow-up (NFU) steering tiller micro switch—likely caused an unintended rudder movement and loss of control.
Contributing factors included a delayed crew response in executing emergency steering procedures, which reduced available time to prevent impact. Post-casualty inspection identified internal cracking and moisture ingress in the tiller’s rubber protective boot, leading to electrical malfunction. The steering gear manufacturer later confirmed similar issues in other vessels and issued a Safety Bulletin citing micro switch failures in NFU tillers delivered between 2002 and 2009.
Actions Taken
Following the incident, the vessel operator replaced both bridge wing NFU tillers, “in-command” push buttons, termination cards, and the power supply transformer with original equipment manufacturer parts. Identical components were also replaced on two sister vessels with comparable steering systems. Refresher training was conducted for bridge and engine teams on transferring steering control and using emergency override systems. The manufacturer’s Safety Bulletin was distributed to vessel operators worldwide to raise awareness of potential failures in similar tiller assemblies.
Lessons Learned
- Immediate response to steering failure is critical during confined or maneuvering operations where hazards are nearby.
- Routine inspection of steering control components, including tiller micro switches and rubber protective boots, should be emphasized to detect degradation or moisture ingress.
- Bridge and engine crew training must include scenario-based drills simulating loss of primary steering to ensure quick transition to emergency modes.
- Redundant verification of steering transfer before departure can help detect latent control faults.
- Safety communication from manufacturers, such as bulletins, should be promptly reviewed and acted upon by vessel operators.
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Source: NTSB
