Why large AIP submarines do not solve the range problem

Could Australia or Canada avoid nuclear propulsion by buying a large AIP submarine with advanced batteries?

Not with an established design suited to their distances; available conventional boats did not provide the required long-range operating scope.

The market lacked a proven large AIP submarine for this mission. Japanese designs approached parts of the requirement but were not equivalent to the long-range boat under discussion. German submarines could struggle even with the distances between Australian bases before reaching an operational area. Canada's Upholder purchase likewise reflected the scarcity of suitable alternatives, since those boats had originally served as insurance against interruption of Britain's nuclear-submarine production.