Australian submarines incapable to operate by... rust

According to the Australian Broadcasting Corporation, this year half of the six conventional Collins submarines will not go to sea.** The origin is the extraordinary corrosion of the rigid hull at HMAS ‘Sheean’, the 5th unit in the family, discovered by the ASC shipyard engineers. The navel under "Sheean" was laid in 1994, was launched in 1999, and a flag was raised on it 2 years later. So it's a middle-aged unit, but inactive modern. In view of the crucial safety concerns associated with the ability of “Sheean” to scope a maximum depth of immersion (which is officially about 300 metres), the ASC reported that **repair would last at least until Christmas.**