Here is an old post from Ray Hughes you might be interested in:
An alternative to replacing the rubrails may be to use a product called "Vinylon." It is designed to adhere to flexible poly-synthetics and rubber, such as marker buoys. I bought a quart of this stuff from Seattle Marine for about $18.00. Follow the instructions and you can't go wrong. A lot more cost effective than replacing the rubrails. Good luck with your project. --Ray Hughes, 1971 E-29 "Capricious."
I've seen this on Ray's boat and it looks good. I'll be doing the same when I get a chance.
--Paul
E29 "Bear"