A requirement to replace worn underwater bracket bearings in HMAS Parramatta without impacting the ship’s mast upgrade schedule has led to the team at the Warship Asset Management Alliance (WAMA) coming up with a unique and innovative solution.

For the first time in the history of the Anzac class frigates, the A bracket bearings have been changed while the ship was still afloat.

The A bracket bearings support the propeller shafts between the ship’s hull and the propeller, and worn bearings usually means the ship must be dry-docked for the replacement to take place.

Worn bearings usually means the ship must be dry-docked for the replacement to take place

WAMA Maintenance and Readiness Manager Mr Sam Matts said this was not only an expensive evolution but also increased the amount of time that the ship spent in the shipyard.

“Upon recognising the challenge, which was to repair the defect with minimal impact to the ship’s operational schedule, we engaged various stakeholders to come up with a solution,” he said.

“That led to IKAD Engineering partnering with a commercial diving company to provide the requisite underwater engineering skills.

“The opportunity to conduct preliminary works and test some techniques was initially trialled on HMAS Stuart at the Common User Facility in Western Australia.

“This required the removal of all of the covers surrounding the A brackets, measuring clearances and rebuilding – all carried out underwater.”

Navy Clearance Divers then commenced work on the task by removing the covers from Parramatta’s hull.

The initial estimate of the bearings replacement taking almost two weeks was, in reality, reduced to less than a week

A video link between the divers and the surface allowed site engineers to monitor and supervise the work.

Following that, preliminary work to prepare for the replacement of the bearings was undertaken, and the actual removal and replacement was carried out a few days later.

Mr Matts said once the replacement bearings had been installed, and all walls had passed integrity testing, Parramatta was announced ready-for-sea.

“This was an excellent effort by all involved, and the initial estimate of the bearings replacement taking almost two weeks was, in reality, reduced to less than a week.

“This is exactly the innovation that we hope to explore further in our support of the Anzac class – the window of opportunity was very tight but working together as a collaborative team has generated a very real benefit.”

The WAMA is a collaborative alliance between BAE Systems Australia, Saab Australia Pty Ltd, Naval Ship Management Pty Ltd and the Commonwealth of Australia.

Its mission is to deliver materially seaworthy Anzac class warships, driving long term efficiencies to enable Navy to fight and win at sea.

This article by LEUT Gary McHugh originally appeared in Navy Daily.