Recently did my skippers ticket and tried to clarify why a windsurfer could not go offshore to rotto i originally thought it was due to the shipping channel but..
Technically a vessel less than 3.7m in length can not legally travel more than 5nm offshore even with all necessary safety gear.
This would rule out a windsurfer including an rsx or a mistral one design
One thing im not technically sure about is that the waters inside rottnest island are classified as inshore protected waters and there is a exemption for epirbs within a 5nm radius of the zone.
but who is goin to catch you on slalom gear/wave gear in 25knots of wind and km's of coastline to check in. Unless they get one of those super ferries to chase you you, well then you're stuffed