: I'm about to start building a kayak for a rather large guy. I figure around
: four hundred pounds. I was planning on increasing the sheer of a Mill
: Creek 13, and wanted to know if someone has a way to calculate how much I
: would need to add to give it another 100 pounds of capacity.

With someone that size I'd think you'd need to increase the strength of the materials too. The forces of just getting into the boat would be much more than gradually loading cargo in addition to the average size paddler. Might call CLC?

Bill H.