Editing Double-hulled tanker (section)

==Reasons for use==
[[File:SPT Champion in Curaçao.JPG|thumb|The double-hulled ''SPT Champion'' in [[Curaçao]]]]

A number of manufacturers have embraced oil tankers with a double hull because it strengthens the hull of ships, reducing the likelihood of oil disasters in low-impact collisions and groundings over single-hull ships.<ref name="CEIDA">{{cite web|url=http://www.ceida.org/prestige/Documentacion/dobrecascopetroleiros.pdf |archive-url=https://web.archive.org/web/20120417093518/http://www.ceida.org/prestige/Documentacion/dobrecascopetroleiros.pdf |archive-date=2012-04-17 |url-status=live|title=Double Hull Tankers – Are They the Answer?|publisher=CEIDA|access-date=18 September 2014}}</ref> They reduce the likelihood of leaks occurring at low speed impacts in port areas when the ship is under pilotage. Research of impact damage of ships has revealed that double-hulled tankers are unlikely to perforate both hulls in a collision, preventing oil from seeping out. However, for smaller tankers, U-shaped tanks might be susceptible to "free flooding" across the double bottom and up to the outside water level each side of the cargo tank. Salvors prefer to salvage doubled-hulled tankers because they permit the use of air pressure to vacuum out the flood water.<ref name="CEIDA"/> In the 1960s, collision proof double hulls for nuclear ships were extensively investigated, due to escalating concerns over nuclear accidents.<ref name="OkumotoTakeda2009"/>

The ability of double-hulled tankers to prevent or reduce oil spills led to double hulls being standardized for other types of ships including oil tankers by the [[International Convention for the Prevention of Pollution from Ships]] or [[MARPOL]] Convention.<ref name="ChircopLindén2006"/> In 1992, MARPOL was amended, making it "mandatory for tankers of 5,000 dwt and more ordered after 6 July 1993 to be fitted with double hulls, or an alternative design approved by [[International Maritime Organization|IMO]]". However, in the aftermath of the [[MV Erika|Erika]] incident of the coast off France in December 1999, members of IMO adopted a revised schedule for the phase-out of single-hull tankers, which came into effect on 1 September 2003, with further amendments validated on 5 April 2005.<ref>{{cite web|url=http://www.imo.org/OurWork/Environment/PollutionPrevention/OilPollution/Pages/constructionrequirements.aspx|title=Construction Requirements for Oil Tankers|publisher=International Marine Organization (IMO)|access-date=18 September 2014|archive-date=25 June 2012|archive-url=https://web.archive.org/web/20120625095551/http://www.imo.org/OurWork/Environment/PollutionPrevention/OilPollution/Pages/constructionrequirements.aspx|url-status=dead}}</ref>

After the [[Exxon Valdez oil spill|''Exxon Valdez'' oil spill]] disaster, when that ship grounded on [[Bligh Reef]] outside the port of [[Valdez, Alaska|Valdez]], [[Alaska]] in 1989, the US government required all new oil tankers built for use between US ports to be equipped with a full double hull.<ref name="FaureHu2006">{{cite book|last1=Faure|first1=Michael G.|last2=Hu|first2=James|title=Prevention and Compensation of Marine Pollution Damage: Recent Developments in Europe, China and the US|url=https://books.google.com/books?id=E5NafsG5RiEC&pg=PA14|date=1 January 2006|publisher=Kluwer Law International|isbn=978-90-411-2338-1|page=14}}</ref> 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.<ref>{{cite web|author=Skinner, Samuel K.|author2=Reilly, William K.|url=http://www.akrrt.org/Archives/Response_Reports/ExxonValdez_NRT_1989.pdf|title=The Exxon Valdez Oil Spill|publisher=US Federal report|access-date=18 September 2014|url-status=dead|archive-url=https://web.archive.org/web/20120415122233/http://www.akrrt.org/Archives/Response_Reports/ExxonValdez_NRT_1989.pdf|archive-date=15 April 2012}}</ref>