I found the same problem in my Arctic Tern, and I replaced the seat with another seat from Sealline, which is a little thicker and molded. Then I added a foam wedge about 1-3/4" high at the front, tapering down to nothing over 4". This adds support under your thighs, which immediately solved the problem. The wedge will even work with your stock seat, but not quite as well. All the good fiberglass seats I've seen share that one feature--the under-thigh support.

Here's the URL for the seat:
http://www.cascadedesigns.com/sealline/touring.asp?Action=TouringSeat

Good luck and numbless paddles in your future,
Mark

: I have a couple of Pygmy boats, an Arctic Tern and a Coho. I have REALLY bad
: numbness in my legs after 20 min of paddling with the therm a rest pad
: that came with the boats. I carved a mini-cell seat which I transfer back
: and forth between the two boats but it is only marginally better. I still
: end up with no feeling in my legs after some time in the boat. I have
: followed the discussion of this numbness problem on the bbs for some time.
: I recently went out for over two hours in a rented fiberglass double with
: a molded seat and had no symptoms at all. I am realistic enough to know
: that I will never make my own molded fiberglass seat so that leaves trying
: to find one that could be fit into the Pygmy boats OR other commercially
: available seats that might provide the same kind of support that a molded
: fiberglass seat does.

: Has anyone solved serious leg numbness with a commercially available seat fit
: into a Pygmy kayak?

: Mike