Sorry to write stupid things. Solder in, I ment. Somtimes I mix up words.
Now I tried extra strong silicon. When I return from Germany in February to my boat in Fl, I will tell you if it works.
The originals are not sewed in, they are some kind of glued from below. With the first cupholder I made the mistake to tear of the ring. That harmed the tramp so it started after some time to tear. With the others I just cut the holder out and let the ring sit. Then I glued the cupholder from the top. The reason is that I lost the others because they were under the tramp and we were going pretty fast. I hope if they get loose I will be able to see it and get them. And I am pretty sure the tramp will not suffer anymore because the origenal cupholder rings are still in.
Sewing of course sounds very good. But how to do it. I couold go to some tent maker or so. But again I will have to take the wave apart. And I am always only limited time here.