The Coulombi Egg Tanker is a design that is aimed at reducing oil spills. It was approved by the

International Maritime Organization The International Maritime Organization (IMO, French: ''Organisation maritime internationale'') is a specialised agency of the United Nations responsible for regulating shipping. The IMO was established following agreement at a UN conference ...

(IMO) as an alternative to the

double hull A double hull is a ship hull design and construction method where the bottom and sides of the ship have two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull which is some dist ...

concept. The

United States Coast Guard The United States Coast Guard (USCG) is the maritime security, search and rescue, and law enforcement service branch of the United States Armed Forces and one of the country's eight uniformed services. The service is a maritime, military, m ...

does not allow this design to enter US waters, effectively preventing it from being built..

Concept

The design is an enhanced

mid-deck tanker A mid-deck oil tanker is a tanker design which includes an additional deck intended to limit spills if the tanker is damaged. The extra deck is placed at about the middle of the draft of the ship. This design is an alternative to the double-hull ...

and consists of a series of centre and wing tanks that are divided by horizontal bulkheads. The upper wing tanks form ballast tanks and act as emergency receiver tanks for cargo should the lower tanks be fractured. The lower tanks are connected to these ballast tanks by non-return valves. When a lower tank is damaged, the incoming sea water pushes the oil in the damaged tank up into the ballast tank. Because of the

hydrostatic pressure Fluid statics or hydrostatics is the branch of fluid mechanics that studies the condition of the equilibrium of a floating body and submerged body " fluids at hydrostatic equilibrium and the pressure in a fluid, or exerted by a fluid, on an i ...

, there is an automatic transfer out of the damaged tank.

Advantages

The double-hull design is aimed at the probability of zero outflow. In low energy collisions where only the outside hull is penetrated, this will be the case. However, in high energy collisions both hulls are penetrated. As the tanks of a double hull tanker are larger than those of MARPOL tankers and pre-MARPOL tankers and the height of the cargo above the water line is higher, the resulting spill can be much larger than these single hull designs. In the Coulombi Egg design spillage is greatly reduced, possibly to zero. Where a double hull VLCC has a ballast tank coated area of about 225,000 m³, in a Coulombi Egg tanker this area is reduced to 66,000 m³. This reduces maintenance and corrosion risks, which otherwise may result in structural failure, as was the case with the ''Erika'' and ''Prestige''.

References

Bibliography

External links

*{{Commonscatinline + + Ship types Ship design Shipbuilding