The New Zealand Transport Accident Investigation Commission (TAIC) has published a report after bulk carrier Achilles Bulker lost its rudder in 2023.
What happened
On 24 July 2023, the fully loaded Achilles Bulker was under pilotage outbound from the Port of Tauranga. Shortly after clearing the harbour entrance, the ship’s heading began to swing to port and deviate from its intended track in the centre of the channel. As the bridge team took corrective action to return the ship to the centreline of the channel, the ship’s rudder broke off and the ship continued out of the channel into shallow waters. The pilots and ship’s crew successfully anchored the ship using both anchors, narrowly avoiding grounding.
Why it happened
The rudder pintle was missing, which left the bottom of the rudder unsupported and allowed excessive movement in the rudder system. The rudder broke off when the rudder palm fractured on both sides of the rudder stock .
The pintle dropped out of position and was lost before the ship lost its rudder. As a result, excessive lateral loads had been placed on the rudder palm over time, contributing to the development of fatigue cracks in the palm on both sides of the rudder stock.
In 2021, Achilles Bulker underwent maintenance during a scheduled dry dock period. During this period the rudder pintle assembly was removed and later reinstalled. It is virtually certain that the way the rudder pintle assembly was reinstalled did not ensure that the pintle would remain in place during normal shipboard operations.
The way the rudder pintle assembly was reinstalled meant that components used to secure the pintle in place failed, allowing the pintle to drop from the bottom of the rudder.
The Transport Accident Investigation Commission (the Commission) has identified a safety issue relating to the quality assurance and oversight used during the pintle reinstallation.
The Commission has made recommendations to address the safety issue.
Lessons learned
Pintles are critical components of a critical system and should be treated as such. The way the rudder pintle assembly is installed is important for the durability of the rudder system and for preventing loss of the pintle and rudder.
Ship owners and operators have overall responsibility for the ship. It is important that they have sufficient oversight of repairs to components of critical systems to ensure the repair is effective.
The loss of controlled manoeuvrability of a ship is particularly dangerous when navigating in pilotage waters. Pilots and ship crews need to be prepared for such an event.
Download the report: TAIC MO 2023-2025