Abstract: A system of puncture-resistant and tear-resistant flexible skin, placed inside the steel cargo tanks of existing or newly-built crude/product carriers (oil tankers), enclosing their liquid cargo with a leak-proof seal while creating a void space between the outer surface of the flexible skin and the inner surface of the steel tanks. The purpose of the invention is to prevent leakage of cargo to the sea in case of groundings or collisions, wherein the steel bottom or side hull of the ship is breached but the flexible inner skin remains intact due to the distance separating it from the steel outer hull and its property to deform, yield or "give". Arrangements and means of attachment are further described.