Why not go first to a furniture store that sells water beds, and get a water-bed patching kit. That's virtually certain to work.
I've never bought a water bed, but every one I ever saw came with a patching kit, and I understand that it's not unusual to have to use them -- and that they really work, too.
I would not have expected RTV to work long -- at all, really -- in that application.
__________________
-- Carl
|