We always seem to justify building subs here, in order to...

We always seem to justify building subs here, in order to preserve our ship building industry / skills in the event of hostilities.

Funny thing is that there seem to be no concerns around the closing of the BP Bulwer Island oil refinery in Brisbane, which is Australia's source of F44 grade helicopter fuel.

If war were to break out in our region, I would think it would be far more important to have a home grown source of helicopter fuel, than a ship building industry, where a new build might take half a decade to complete.

Yep, next subs should be off the shelf German diesel (or Stirling engine) subs. After all, the really difference is the skill and training of the crew, where Australia is second to none.