Sounds like a butyl caulk compound to me. Mine wasn't dry after over thirty years.
Replaced all of mine with butyl tape. Same as the caulk just easier to work with. A moderator on sailboatforums.com sells it. Screen name of mainsail or mainesail, he has a tutorial thread I posted here a few weeks ago. I can't find it now as I'm on my Android.
Craig - AKA Some Clueless Idiot
The person who is saying something is impossible should not interrupt the person who is doing it.