Read the information that Nick has written on his site. It will be helpful. Use the search feature and go back through all the archives. Use a search engine and look for kayak and canoe design. John Winters, among many others, have written articles about designing a canoe or kayak. And then you can consider the way I do it...which certainly doesn't mean I know what I'm doing because I haven't built the perfect boat yet (or even a boat that I wouldn't make some changes with): "If it looks good, it is good."