Двухкорпусные танкеры: конструкция, преимущества и недостатки

A double hulled tanker refers to an oil tanker which has a double hull. They reduce the likelihood of leaks occurring compared to single hulled tankers, and their ability to prevent or reduce oil spills led to double hulls being standardized for oil tankers and other types of ships including by the International Convention for the Prevention of Pollution from Ships or MARPOL Convention. After the Exxon Valdez oil spill disaster in 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.

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. 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. After the Exxon Valdez oil spill disaster, when that ship grounded on Bligh Reef outside the port of 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. 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.

Although double hulled tankers reduce the likelihood of ships grazing rocks and creating holes in the hull, 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. Double hulled tankers, if poorly designed, constructed, maintained and operated can be as problematic, if not more problematic than their single hulled counterparts. and because the steel weight of doubled hulled tanks should not be greater than that of single hulled ships, the individual hull walls are typically thinner and theoretically less resistant to wear. Double hulls by no means eliminate the possibility of the hulls breaking apart. Due to the air space between the hulls, there is also a potential problem with volatile gases seeping out through worn areas of the internal hull, increasing the risk of an explosion. Although several international conventions against pollution are in place, as of 2003 there was still no formal body setting international mandatory standards, although the International Safety Guide for Oil Tankers and Terminals (ISGOTT) does provide guidelines giving advice on optimum use and safety, such as recommending that ballast tanks are not entered while loaded with cargo, and that weekly samples are made of the atmosphere inside for hydrocarbon gas.