Double Hull Paradox

It’s over eleven years since the US adopted the Oil Pollution Act (OPA 90) following the Exxon Valdez supertanker grounding incident, which resulted in 11 million gallons of oil being spilled into Prince William Sound, Alaska.
As a result, the International Maritime Organization (IMO) introduced global double hull standards in 1992 under the International Convention for the Prevention of Pollution from Ships (MARPOL) to further protect the environment. In 2002, the European Commission adopted regulation 417/2002 making the IMO’s now accelerated phase out schedule for single hull tankers mandatory.

Despite these measures, in 2010 the International Tanker Owners Pollution Federation Ltd (ITOPF) reported that the number of large spill (considered to be > 700 tonnes) saw a slight increase when compared to the previous ten years. The total amount of oil lost to the environment in 2010 showed an increase against figures for 2008 and 2009.

As the IMO looks to strengthen its ability to prevent pollution from ship operations through the development of regulations including the International Code of Safety for Ships in Polar Waters (the Polar Code), the designation of special areas where mandatory methods for the prevention of sea pollution are required, and the accelerated phase out of single hull tankers, the fact remains that double hulls present a number of challenges and are not a panacea.

While the amended double hull regulations plan to increase the protection of the environment, an unexpected side effect is that some double hull vessels have become more susceptible to operational and maintenance issues. One of the main challenges has been accessing the cargo and bunker tanks following an accident to remove the fuel and cargo onboard in a timely manner.

The current trend for giant ships has resulted in a re-design to maximise cargo capacity.As a result, on many modern giant ships the bunker tanks are located under areas such as the accommodation block – an excellent location in the event of a collision as it provides additional safety, however in the event of a wreckage the tanks become extremely difficult, if not impossible to access.

European-based JLMD Ecologic Group’s FOR and ORA Systems address this weakness in a ship’s design by increasing the cargo and bunker tanks connectivity and speeding up lightering operations. Recovering pollutants from the cargo and bunker tanks reduces not only environmental damage but the financial damage to the shipowner.