ONCE derided as "dud subs", the navy's six Collins submarines are now performing better than ever following a concerted effort to get more to sea rather than ashore undergoing maintenance.
Where once only one of the six submarines was available for operations, the submarine force can now deploy two and often three at a time.
In a progress review of efforts to improve the Collins fleet, UK submarine expert John Coles said this turnaround was remarkable.
The Collins boats were delivering a level of performance which would not have been viewed as possible two years ago, he said.
"It has been an enormous pleasure to observe the astonishing turnaround of a seriously failing project to one that should, within just two years, achieve or better International Benchmark performance," he said in the report.
The Australian-built Collins submarines have been controversial throughout their service. A succession of technical problems attracted scathing headlines, branding them "Dud subs".