Jev, I will start by saying I wouldn't have a clue. But just thinking out loud in the hope that it will cause discussion.

A current is a continual flow, while a tide is a rise and fall of water. That rise in water also causes a flow of sorts or a localised current (for want of a better analogy).

The EAC for example runs from approx. Fraser Is in QLD to Tasmania before it heads off back to the east below NZ. So for the guys heading to Norfolk Is, they would primarily be concerned about the north/south aspect of the current.

The coast line closest to the EAC would be the east coast of Aust. So a rise in tide, could cause a westerly flow in localised water, possible deflecting the EAC slightly west and opposite for a failing tide. If this is true, or even measurable, I wouldn't have the faintest. But logical in my mind. I am happy to learn otherwise.

Does an oceanic chart have Tidal Diamonds?

You can see the currents here:www.bom.gov.au/oceanography/forecasts/idyoc14.shtml?region=14&forecast=2

SandS said..

question for the nsw crew ...whats the tide range up there say around Sydney ?

The range between a neap low and high tide is about 1 metre, between low and high of a spring tide about 2 metres.

plenty here on tides ocean temp and swell,not much on the EAC
the swell buoys are very useful if you are going offshore or through a bar (or are a surfer )

new.mhl.nsw.gov.au/data/realtime/oceantide/

new.mhl.nsw.gov.au/docs/project_sheets/NSW%20Coastal%20Conference%202011%20OceanWaterLevels.pdf