Must have been a decent summer in 2013!
https://www.rib.net/forum/f8/how-do-...bes-56832.html
With any product you’re applying, then try on hidden area first. I like Rib Revive cleaner, but not sure it will work on sun block. Quick search throws up citrus cleaner or rubbing alcohol. After cleaning, wash the whole lot down with a light detergent and rinse. If it’s black hypalon and not fabric impression, 3M marine conditioner should offer some protection.