Despite their very disappointing problems, that has reduced reliability and required continuing expensive fixes, when they work they can work very well. In exercises with the US Navy since 2000 Collins class subs have "sunk" (gotten unseen within firing range of);
3 Los Angeles class nuclear subs. 2 40,000 ton amphibious assault ships And the Nimitz class aircraft carrier USS Abraham Lincoln
HMAS Rankin "sinking" USN frigate in 2005 exercise.
http://www.youtube.com/watch?v=d8Kv4rqR6RQ
Modern submarines are the most complicated machine made by man, problems with new cutting-edge designs are not uncommon. The Royal Navy has had major problems with their recent Astute and Upholder class subs.
http://www.bbc.co.uk/news/uk-scotland-11977871
The faulty welding on HMAS Collins was done in Sweden.
On the current crewing problems for the Collins Class, it is argued that these could be much alleviated if half the sub fleet was based in Sydney, as not all east coast Naval personnel, interested in submarine service, are able to uproot and move their family to Perth.
That said, the first Collins Class sub is nearly 20 years old now, the Japanese Navy replace their subs at around this age.
