In search of a flat hinge with round edges, I found this hinge. The rubber strap allows some flexibility in the movement, but this does not bother me. The price is great. 4mm countersunk screws fit very well. Have now installed four hinges on the floor of the cockpit. I am happy!
I wanted to use the hinges for the wooden flaps under the sleeping areas of the bunks. However, that didn't work because the rubber warped after it was opened, so that the boards couldn't be returned to their original position when they were closed. Unfortunately, I don't really understand what the hinges can actually be used for under these circumstances...