It's the loudest thing in the ocean according clueless military experts on the internet, and the Liberal party (to discredit Kim Beazley). Because I'm lazy I'll just quote myself
"The hydrodynamic noise signature was loud at high speeds. The main cause for this was that the hull design was modified and no model was created to test the hydrodynamics of the new design. There were arguments over who should pay for the model, so it was never made. There were also issues of propeller cavitation but I'm not sure of the details of that. Note that none of these were issues related to Australian workers in Adelaide, these were design issues.
It's also worth pointing out that the main source of noise in the Oberons were machine vibrations being transmitted through the hull. Kockums overcame this in their submarines by placing the machinery on platforms that were mounted on rubber isolation blocks, and connected to the hull via flexible hoses rather than rigid pipes. So design wise the Collins class was on the right path to being much more quieter than the Oberons, if only someone tested the modified external hull shape."
Oh and those issues were fixed.
What investors? And I'll think you'll find it existed because we needed a new submarine.
What contractors?
That never happened, work started straight away. Although it's arguable what the hell Rockwell were doing on the combat system--which was bar far the biggest flaw in the Collins and oddly enough never mentioned. You forgot a lot of other Liberal propaganda. Like Kockums bribing Labor MPs. They were billions of dollars over budget. They had massive building flaws because Australians can't make stuff (only mine and farm).