I once repaired a damaged rubber rubbing strip (hefty 2" wide and high moulding) using black 5200. It was a portion running across the bow. I needed to fill lots of voids and almost used a whole tube. Worst part was removing the (garbage bag full of) sticky masking tape.. My clothes were shot after that.
Weeks later we were late back and couldn't get to the ramp in time to catch the tide for haul out. 6 guys pulled the 1000lbs boat out by the nose, up almost two feet with no damage at all.
That stuff is indestructible.