Mike--

I'm backing away from by idea about bezier equations.

I did some sketching this morning and the more I look at it the more I like Nick's first idea, seconded by Jay.

You're right that the draft of the boat needs to be taken into consideration to understand the underwater shape of the hull. In line with keeping it simple, why don't we say, "the draft of the boat is 5 inches and the rocker number (RN) is .156 or some other similar value." This expresses how fast the underwater lateral area dies out as we move towards the end of the boat.

Numbers will never express the total handling of a kayak and we're not trying to define the exact shape of the keel line, just give a feel for this characteristic of the boat. One thing that is going to help us in this area is that by moving to the 50% draft waterline we do move away from bow/stern idiosyncrasies and we can assume that the keel line will be a fair curve. Also we are not trying to give a definition that will work for all possible boats, just one small subset, kayaks, so we can assume kayak-like shape.

Mike Scarborough