There's something to be said for taking apart a sail and copying it and stitching it together. In the past I've learned a lot from taking things apart to get an idea how they work. But I wouldn't it be a better idea to get some cloth and practice cutting and stitching on smaller pieces? It might be a nice break from the cerebral work of learning about saildesign and actually designing a sail. I'm not against copying per sé as long as it's done to gain an understanding of the processes involved, after all a lot of great artists have started that way.
Would a good domestic sewing machine be good enough, or am I going to struggle with it or, even worse, break the machine?

Great info so far, thanks all