Joaquin,

Hey, You speak and write more then one language is really cool....me, I speak ony English, and rather bad English at that!

I like the idea, simple, wooden and easy to make and fix. Then, amidst my fourth or fifth beer it suddenly struck me a way to make rudder peddles and a foot brace at the same time:
Your idea of a bar across except it's a hardwood dowel, with two shaped pieces of plywood screwed onto a contoured block of wood that's on the dowel, with a spaceer to keep the pedal rotaing at a specific place on the dowel. The pedals rotate, but instead of Yakimas or others, they still are fixed in space when used as a brace.
What really gets me is the range of adjustments manufacturers make in store-bought rudder/foot pegs. The range is so great that for a 18 foot yak, the range could accomadate a child to a giant. That's absolutely ridiculous. An adjustment range of just inches is more then enough. I'm going to put something stogether and post the results for everyone. Thanks for the idea!!