Abstract: This invention relates to flexible internal liners for reducing the amount of oil spilled by oil tankers due to groundings, collisions, and other major accidents. The liner comprises a flexible oil-resistant impermeable plastic or rubber, which preferably is reinforced by steel mesh or woven aramid fibers. In one embodiment, a independent segment is provided in each bay between two stiffeners. The horizontal edges of each liner segment are coupled to the stiffeners, near the ends of the stiffeners, to provide enough material for the liner to be pushed inward a substantial distance if a collision or grounding occurs. The edges can be secured by detachable clamps; this will provide watertight seals during normal operation, while allowing the segment to be detached and opened when the hull is inspected.