Hi I got this reply directly from Australian Customs
When you arrive in Australia, there are two clearance options depending on when you intend to leave. If you intend to leave within twelve months, you may be granted a cruising permit
or asked to provide a security
for temporary importation.
Both options provide access to Australian waters and lands.
1. Control permits
A control permit
will be issued to the Master or owner of the craft if Customs and Border Protection is satisfied the craft is touring Australia for non-commercial purposes. Control permits may be issued for specified periods, for example three (3) months or the length of time of the Master's visa, whichever is less, however the maximum length of time a permit will be granted will not exceed twelve (12) months.
Extensions of the permit may be granted on application, provided that you have an appropriate visa however extensions will only be granted for a maximum of three (3) years within a four (4) year period commencing from the date of arrival of the craft in Australia.
You will be required to comply with certain conditions attached to the issue of the permit.
Control permits will not be issued if:
the vessel is owned or operated by an Australian resident unless exceptional circumstances apply;
the vessel is to be used for commercial
purposes (e.g. charter
, hire or lease);
the vessels, or parts
of the vessel, are to be sold or listed for sale
If circumstances of the craft's presence in Australia change, you are required to advise Customs and Border Protection. Failure to do so can result in a cruising permit being revoked and the vessel being deemed imported at which time payment of duty and tax will be required.
For further information please click here http://www.customs.gov.au/faq/Yachts.asp
Hopefully this will help you.