From what i recall the gov. rego on landyachts is for Pt. Gawler beach ONLY as this is the only place sailed that both landyachts and cars could mix.
The rule is that if a (standard) car can drive on the area (without going through a control gate etc) the area would be regarded as a public road. So shopping centre care parks are public roads... even your home drive way is a public road up to a closed gate.
Now Goolwa beach... West of the access road is "NO vehicle access" this what is regarded as Goolwa town beach.
Now East of the beach access road you could sail and with no rego. you wont get to the Murray mouth as it gets too soft even 4wd's about half way there. But you will get a l-o-n-g way down the beach, I did it once late on a moon light night.
A good indication of surface softness is if standing / walking you leave FULL footprints its to soft.
Here is a link to a trip done to the Murray mouth from the other side done many years ago.
www.seabreeze.com.au/forums/topic.asp?TOPIC_ID=37055The rego is 3rd party property the same as included in your car rego. Any landyacht can be registered ... any size or shape