Hi,
Not sure where the information on the vessel came from, but most probably from a web site "A Rorke Family Research Project" founded by an American school teacher April Blakeley. I started researching my wife's family in 2005 and found some interesting information on April's site. I have subsequently identified a lot more information, and have been to the ancestral home in County Galway, Eireland.
I have published this, amongst my own family research on our website.
http://ateades.tripod.com/Unfortunately the majority of the information is concerned with James Rorke, one of five sons of James and Julia. These were, in no particular order, James, Michael, Benjamin, Thomas and John.
Michael, James, and Thomas emigrated to South Africa in 1823, as single persons. Benjamin arrived some time later with his wife, and John stayed in Eireland and took over the farm his parents rented from the Earl of Clancarty.
Have a look at the site and if there is more information you require, I will try and answer your queries.