Aratere Propeller
On 5 November 2013, an issue with one of the ferries carrying passengers between New Zealand’s North and South Islands hit the news headlines: a 6.5-tonnepropeller had fallen off the Aratere and sunk into the waters near the Tory Channel.
While the ship was able to complete its journey safely, Seaworks, with extensive salvage experience (such as with the Rena in 2011) and knowledge of the Cook Strait waters, were called on to help locate and retrieve the missing $200k propeller.
We started with an investigation, which involved using multi-beam echosounder sonar equipment and a remotely operated vehicle (ROV) with cameras to locate the propeller and identify the GPS coordinates. This revealed that the propeller was lying flat and partially buried 123 metres below sea level – and to complicate the recovery operation it was near the Tory Channel, an area known for extreme tidal flows and subsea currents.
The Seaworks solution
- Creating the space needed to install a specially designed lifting strop for the propeller. This involved attaching a subsea jetting unit to our hydraulic work class ROV and using it to blast a hole in the sand and rocks underneath the propeller
- Using the ROV manipulators (arms!) fitting strops around the propeller’s blades and part of the shaft
- Employing the ROV to attach a recovery line to the propeller from the sea’s surface
- Using the Brandywine (a self-propelled barge we owned at the time) to lift and recover the propeller
- Loading the propeller onto the Brandywine for delivery back to Wellington and an intensive investigation by the Transport Accident Investigation Commission.
Today the Aratere is back in action, carrying up to 600 passengers a day as one of a fleet of ferries that, combined, cross the strait 4,000 times a year. Whenever one of our team sails on the ferry, they think proudly of the day they helped to rescue one of the propellers below.
