Changing to a BVI registration
is relatively painless - usually all you need to do is get the boat measured by an approved measurer if the boat is not already BVI registered. The red ensign flag is available to Commonwealth (or EU) citizens whereas Americans and others need to open up a BVI registered company and register the boat in the corporation's name. This might be worth doing for you as well. The company costs about $750 per year all told but has some advantages - particularly in terms of avoiding inheritance taxes
, since all that would need to be transferred are the "shares" in the company and thus no taxes
Would the boat be physically located in Oz or elsewhere?