Well .. first I'd like to thank all of you for your inputs. Second - I had my own "Aquasport" decals cut in my local vinyl store ($15) and they turned out beautiful. I posted the image I used to have the decals cut somewhere in the forum, but you can PN me if you want me to send it to you. It's 1558x416px so every vinyl store should be able to work with it.
Anyway - after a lot of research and thinking I finally decided not to re-paint my boat. Partly because I screw stuff like that up easily and second - it was too expensive. I decided to go for Poly-Glow. I understand that this locks me in with the stuff and that the boat might never be paintable again - but let's be realistic: This boat is 30 years old and it was on it's way into the afterlife (do boats dream?) before I got it. I already invested way too much into it and have to come to a close with all the work. To be honest - I didn't expect much from it. So I wanted to make sure any failure wouldn't be my fault. I sanded the boat with 400 grid, used their powder cleaner and finally their chemical cleaner, flushed everything nicely and let the boat dry for an hour. I then applied 6 layers of Poly Glow.
The result is nothing short of amazing. No - it's not a sparkling new coat of color. But it very, very nice. We'll see how it holds up, but even if I have to apply a couple of new layers once in a while - that takes maybe 1 hour or so and I still have 1/2 the bottle.
Judge it yourself. This image was taken about 7 hours after the last layer was applied. It's dry and ready to go. So - for the time being I am restless convinced that this stuff is really an alternative to make your boat look nice again.
Michaela.