Oil Tankers
Double hulls' ability to prevent or reduce oil spills led to their being standardized for other types of ships including oil tankers by the International Convention for the Prevention of Pollution from Ships or MARPOL Convention.
A double hull does not protect against major, high-energy collisions or groundings which cause the majority of oil pollution, despite this being the reason that the double hull was mandated by United States legislation.
After the Exxon Valdez oil spill disaster, when that ship grounded on Bligh Reef outside the port of Valdez, Alaska, the US Government required all new oil tankers built for use between US ports to be equipped with a full double hull. However, the damage to the Exxon Valdez penetrated sections of the hull (the slops oil tanks, or slop tanks) that were protected by a double bottom, or partial double hull.
Furthermore, a double-hulled tanker does not need longitudinal bulkheads for longitudinal strength, as the inner hull already provides this. Eliminating longitudinal bulkheads would result in much wider tanks, significantly increasing the free surface effect. However, this problem is easily corrected with the addition of anti-slosh baffles and partial bulkheads.
Read more about this topic: Double Hull
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