I am descended from the Newland family who arrived at Port Phillip in January 1853 on board the Zes Gesusters. I found a reference on the Prentice family website to a log written on the voyage at http://www.iroots.net/news/2003/john_prentice_sharnbrook_eng...
. It quotes from another website that is now defunct but may give some good leads.
There are also newspaper reports about the ship viewable at the National Library of Australia website www.nla.gov.au
. Go to TROVE and search on "Six Sisters" and on Gesusters. A thanks to Captain and the surgeon is at http://trove.nla.gov.au/ndp/del/article/4789105?searchTerm=%...
I'd be interested if you find any more information. Thanks