Vinyl insert
I recently replace the vinyl insert in my Catalina 22. I don't know if that's what you are considering, but it was fairly simple. The old insert simply pulled out, and the new one was installed using a heat gun to make the vinyl/rubber stay flexible. I used a putty knife to force it into the groove/slot. Catalina Direct recommends placing the replacement insert in a pail of hot water, but this does work; it cools off too quickly. No caulk was used. If you are replacing the entire rubrail, then this advice may be of no use.Johnny HensonGreenwood, MS