I agree with the others. One of those big oversized bowie knives or "survival knives" that are too big to be much good for anything else but chopping can be used to reduce a stave if you don't have a good hatchet. That jig saw won't like wood over 1/2" thick - at least it won't like hickory more than a 1/2" thick. Table saws and circular saws will do a little better, but in reality, if you are going to saw out the profiles of a bow stave, a band saw 14" or bigger is the best route to take.