Are they not all operated out of Wa now?Part of the fleet operates out of fleet base west in Perth and the other part out of fleet base east in Sydney. It’s a dual coastline strategy. Perhaps Adelaide being roughly half way between the two works well.
Not sure of the history behind why Adelaide was chosen to be the centre for submarine construction and servicing back in the 1980s, when the Collins Class project began. These days there is a fair bit of cynical political pork barrelling around it. But perhaps it wasn’t purely just that in the first place. Maybe connected to the amount of heavy auto and machinery manufacturing that Adelaide has a history in, meant there were some synergies. That’s not to say Melbourne wouldn’t have also had the capability to serve this function for similar reasons. Which is where an element of parochial politicking perhaps comes in.