I've been doing research on umiaks and have consulted various books, including Skip Snaith's Umiak and Adney and Chapelle's Bark Canoes and Skin Boats of North America. The design that appeals to me most is a 20 ft unmiak whose plan appears on p. 184 of Adney and Chapelle. It's got nice lines--a flat bottom that's not too wide (this turns out to be a shallow V when it's skinned), a strong shear and ample flare. It's a hunting umiak--Adney and Chapelle say these averaged between 15 and 18 feet, so this seems to be on the larger side. (Skip Snaith's book has a plan for a 17 footer, but the lines of that boat are somewhat different--it's got a wider bottom, for example, and it's deeper, with less flare.) What I'd like to do is shorten it to 15 or 16 feet--i.e., by 25 percent. What I don't know is how to adjust the other measurements--beam, bottom width and depth. I don't think I'd want to simply shorten the boat so much without making it slightly narrower and shallower. Maybe this is beyond my abilities, but I wonder if anyone has advice for me on how I might do this.