The 75ft trimaran will attempt to break solo speed sailing records, including the 24-hour and trans-Atlantic records.
Ellen said: ""There aren't many boats that exist like her ... she's designed to go across oceans very quickly with one person on board."
Her new boat, the B&Q trimaran, has a mast height of 100 feet and was designed by France-based Nigel IRENS and built in Somersby, which is 50 miles north of Sydney, Australia.
MacArthur has been in Sydney for several months to test out the boat while it was being finished.
She said: "We basically said, 'Forget the rule book, we want to build the fastest boat, how are we going to do it?'"
The 27-year-old from Derbyshire said sailing the new boat was "powerful and not as violent as sailing smaller boats".
She was launching the Schroeders London Boat Show via a video link from Sydney on Thursday.
MacArthur's last record attempt, to set the fastest non-stop circumnavigation of the globe last February failed when the mast on Kingfisher 2 broke in the Southern Ocean.
She will sail the new trimaran to Auckland in New Zealand with a crew this month and expects to set off for Cape Horn or the Falkland Islands in early March.
The crew will disembark there and MacArthur will sail solo back to Europe, possibly attempting the 24-hour speed record, which is currently held by Frenchman Laurent BOURGNON.
Bourgnon set the record of 540 miles, average speed 33.75mph in 1994.
From June 2004 onwards MacArthur will be attempting the round-the-world and trans-Atlantic records.