First thanks you all for the good suggestions.
I did a little experimenting over the last couple of days and thought you might be interested in the results.
- A lot of what I thought was loss of stability when I went to the kneeling position was acutally a gain in the ability to edge (under control) rather than loss of stability. When sitting it took a real effort to shift enough weight to heel the canoe. Once on my knees with them spread out even a little weight shift would start a nice heel. On my knees I was much more stable when heeled over and I could heel farther over comfortable than when sitting. Even when kneeling if I sat back far enough I could take most of the weight off the knees and make the canoe react almost the same as when seated.
- Toes straight down took all the pressure off my ankles, but I think I need stiffer toed shoes to sit comfortably that way for a long time. I was in aqua-sock type shoes that flexed a lot and put pressure on my toes.
- Toes back but turned out to the side (instep up into chine) allowed for the longest paddling time. I did not cramp up but about 30 min was as long as I went before a need to quit.
- Putting a seat pad on the web seat really made the most difference. It was what let me do that 30 min stretch. I used a crazy creek type chair with the back folded down so that I had the thickness of both the back and seat to rest on.
- I am beginning to think that the most important idea in getting a seat adjusted for kneeling is getting the right balance between weight on the knees and weight on the seat. Too high and all your weight is on the knees so that any little weight shift causes rocking and you have less stability due to your increased height. Too low and you put more pressure on your feet (comfort issue) and if you take enought weight off the knees it becomes difficult to heel the canoe.
Thanks again for all the help.