The magnetic effect would probably be enough to keep it on the tank on it's own. But saying that if there is a layer of slippery type material between it and the metal , when the tank is moving it would still stay on the tank but slide down or whatever with the movement of the tank. In this instance it's not like a limpet mine, the attraction would be there, but perhaps not enough to keep it in one place due do it not being metal direct to metal. Maybe that was the theory behind it. Does anyone know if it was successful and if so how was it effective. Or was it a well meant idea.- in theory.