.......Errr! No the Sea Witch is not a catamaran;
From the early part of chapter 27; "The only vantage point Lisa could see was a view between some waterfront houses. She drove by slowly, looking intently at the thirty-nine foot Sea Ray powerboat." From that angle, she could see the name currently on the stern, 'Sea Witch'
...........and earlier in the prologue; "'Rachel had proved herself well suited for the task. Three years later, flush with cash from her very profitable businesses, Rachel, with Dirk's reluctant consent, had purchased Atlantis, a second catamaran identical to Ares.'
Trevor taking on another passenger to help him sail sounds like fun! But I recall CJ saying something to the effect that part of the voyage will go by quick, I doubt he wrote in another character for the voyage to Australia.