In response to /Kjell’s commentof February 13, 2020:
Much of the Victoria class' current maintenance problems are rust-corrosion going back as far as their long term UK storage when they were Upholders.
"the submarines deteriorated while in storage and the Royal Navy was not completely forthcoming on their condition during the sale."
-----------
The complex fuel-water -ballast-buoyancy system of "fifteen" tanks for the Collins also suffers from excessive rust-corrosion.
See https://en.wikipedia.org/wiki/Collins-class_submarine#Propulsion_system
And see this Collins submarine image showing 2 of the Fuel Tanks and the Main Ballast Tank .
See https://en.wikipedia.org/wiki/Collins-class_submarine#Propulsion_system
And see this Collins submarine image showing 2 of the Fuel Tanks and the Main Ballast Tank .
This is a major reason for the excessive A$700 million/year total maintenance bill for the Collins.
-----------
-----------
So Naval Group is especially mindful of reducing rust-corrosion problems in the 12 Australian future submarines.
Pete