: I can not envision any combination of arm length, leg length, butt width,
: torso length, shoulder width, foot size or any other linear measurement
: that would accurately predict your weight.

Generally, but not always, a larger person will have larger hips, and perhaps larger hands, which will translate into a wider beam if you use the "hips plus a fist on each side measurement". Also, when fitting the curved deck beams to the shape of your body (for a SOF), larger legs would require more clearance and curvature of the beams, which would increase the volume. Within reason, the anthropometric measurements will get you in the ballpark. Perhaps the anthropometrics should be amended for modern times to say add a fist to either the side of your hips or the front and back of your beer-gut, whichever is largest ;^)

You will want to experiment and modify future kayaks. As Nick illustrates, the main failing of anthropometric measurements is that they do assume a proportional body size. One thing that hasn't been discussed is that these measurements also assume a certain skill level. A novice would probably not want to build a Greenland kayak with a beam determined by the flat of the hand on each side of the hips, as used by many of the Greenland kayakers, and would feel more comfortable with a wider beam. If you fall outside of the "norm" (or like Nick's example, visited the smorgasbord and has thirty pounds of lead in their stomach) then intelligent adjustments may be required. Of course you would apply the same intuition even if your plans had been produced by a CAD program. I feel that there is much more to coming up with workable designs than placing your complete faith in numbers, whether ancient or modern, but you have to start somewhere. Also, if you are only building kayaks for yourself, you only have to discover what works for you. This is a much easier task than marketing plans to the masses, and I have nothing but respect for the designers on this list that find intelligent compromises and manage to make money in the process. But the main reason that spurred me to start work on my own kayak is that I want a custom fit and wish to suit my own personal set of compromises and preferences, rather than accepting the designers assumptions.

Greg Stamer