'Bent can't sit directly on the surfski, although I can. He uses a small piece of a gel shower mat - the kind of thing you attach to your bathtub with little suction cups. Not sure if that might help. For 'Bent, it's more of a sore tailbone thing.
A re-bum-bent surfski?
Had to be done once I thought of it. Sorry.
I would have been disappointed if you didn't.
From my experience, some numbness in your feet is part of the game until you start paddling more regularly. Best thing you can do is try to be more active with your legs - pushing on the footrest on your paddling side and pulling on the strap with the other. Then switch.
Your whole leg probably shouldn't be going numb though. Just your foot, which might feel like more. I remember it being explained to me that there was a nerve running though your heel, and the pressure on that nerve was what caused the numbness. So being active with you legs relieves some of that pressure.
It definitely helps, whatever it is.
Actually, the bath mat suction cup thing is glued to a small thermarest-type kayak cushion under my butt. Helped immensely.
The seat is fine but I think something to do with the pressure on my heel and lack of leg activity as Hansel suggested. I'll try to jimmy the feet around a bit more; it's so strange.
... getting old
I feel (don't feel) your pain :-)