Would like to know, if i register my boat as Australian registration do i need also registered in state registration ?

Yep

I think this would only work if you left Australian waters ie were sailing your yacht arond the pacific, etc for an extended period, then you could drop state registration. Anyone have experience / done this?

Yes. while on extended cruise (2yrs) we let our state registration lapse. you have i believe 3 months upon return to apply for new state based registration.

Appreciate advice - thank you

You need two? State and federal?

Select to expand quote

Mike367 said..
You need two? State and federal?

Only one Mike, just the State rego. Unless you plan to go to other countries.
One step at a time, finish your dinghy, wait for the end of lockdown, and get sailing practice first. BTW you only need it in Vic if you have a motor on the boat. $73 or so per year in Vic and half that for smaller boat < 4.8m long.