why is there 1 high tide / day on the west coast & 2 on the east??

I knew Google had their fingers in a few pies but now they're banking the tide?

tidal banking turned up some info,
the best I've found is www.mesa.edu.au/friends/seashores/tidal_zone.html

basically it's normally associated with northern OZ, where the tide surges through between the Indian and Pacific oceans, the tides in Perth at the moment are more like tides that are in phase and over the next couple of weeks will move back to 2 tide cycles per day.

Interesting. Thanks for pointing it out.