try aquaseal, tackle shops have it . seems to stick to anything, have even made hinges from it. it is self leveling and takes a while to set. can be used on soles of boots, read somewhere once how can with a bit of sand mixed in put new grip to worn boot soles
Yip use aqua-seal “highly recommended”.It did the trick on mine.The top of the boot was split and a blob if it fixed it and has not leaked since.A trick I have found is once you have used it keep it in the freezer and the contents won’t go hard inside the tube.