Here I am living in Woolloomooloo and never heard 'tinny' being used in that way! Can of beer was a tube or a Fosters, VB, Carlton, whatever. Tinny for me is/are (singular or plural? my grammar is slipping) those little aluminium boats that you use to wander the harbour, go fishing, muck around in. The 'little shack down the coast and the tinny' was an ultimate retirement dream of the '50s. Anyway lots of people here have their tinnies tucked under the wharf ready at any time.