The pattern we thought would work the best for the pirate look we were trying to achieve was McCall's 2258. It has everything that a pirate costume needs; the jacket, the shirt with the large gathered sleeves, the waistcoat, the cropped trousers and this one even had the hat!
Even thought Jack Sparrow wears a jacket at the beginning of POTC, Sophie decided to just go with the waistcoat, shirt, hat and trousers as this is the costume seen most throughout the film, plus there had to be some distinguishable differences between mine and Sophie's costumes.
Of course then there was the problem of the pattern we'd decided on to make our costumes not being so female modification friendly so I ended up drafting mine and Sophie's costumes using the purchased pattern as a basis. The costumes actually turned out far different from the McCall's pattern except for the parts where I'd actually followed the original pattern, for instance my coat. At least this way though we were getting what we wanted and it would fit us exactly as we wanted. So that Sophie's waistcoat wasn't too bulky we decided to intervein the shirt pattern into the waistcoat pattern. What I mean can be better seen on the picture on the left of a female pirate costume which helped me with some ideas for modification.
We ended up using some trousers I'd made originally for a Hobbit costume as our pirate trousers and dyed Sophie's a deep grey.
