You need to move your legs around a bit as you spend time in the boat (or any seated device). If the rudders (oops! foot pegs) have you so jammed up that you can't move around some, it'll make you numb.
You also need to have the correct position handy enough that you can quickly get the purchase you need to brace for a sudden wave or whatever.
In both my long boats I can have my legs laying on the bottom for much of the paddle but lift and be in solid bracing position instantly. One is a very low deck, and the other is a narrow higher front deck where I padded down the thigh braces a bit. So I am just not making that big a change to do this. Granted the lower you make the deck the less it helps good rotation, but any boat is a compromise.
As the deck gets higher, or the cockpit gets wider, it takes a little more trial and error to find this sweet spot. But it's there - just keep messing around with the pegs. Another option some like me use is to pad down the thigh pads with minicell, but at your size I doubt that is needed. I suspect that you just have to let go of that always-ready locked in position and the tension associated with it.
posture and padding might help too I love using the “Gold’s Gym” yoga pads from WalMart for seat pads. They are about 1/2 inch thick and fairly firm but give a little. Try a couple layers and see what you think. Good posture really helps too.
I don’t kayak so … … I don’t know if this type is any good but I’ve saved the link in my favs. for a long time now because it looked like a potential good thing .
Sorta looks like the bottom part of the full seat someone posted a link to .
So I removed the old seat yesterday. This thing, I swear if I find who put it in there.... The stop-nuts on the 4 bolts holding it in were in a place you couldn't reach, so I had to sawzall the seat open to get to them. Then the nuts wouldn't come loose, so I had to sawzall off the bolts too. Then I had to do things inhuman to get the damn thing out of the boat.
Adjust the rudder pegs Sliding rudder pegs can be adjusted forward and backwards. I hope you tried this before removing the seat. If not, go ahead and get started. I use a Thermarest cushion for a seat in many boats without a seat.
Yep Yes, I’ve adjusted the rudder pedals before. The situation was equally as uncomfortable even with the pedals further forward. I think the overall seating arrangement was a bad one.
I’m interested to see how it will be with no seat at all. I imaging my vastly lower CG will be impressive.
