Single Hull Oil Tankers Barred From U.S. Waters

Exxon Valdez
On March 24, 1989, the tanker Exxon Valdez ran aground on Bligh Reef in Prince William Sound, Alaska. Within six hours of the grounding, the Exxon Valdez spilled approximately 10.9 million gallons (259,500 barrels) of its 53 million gallon cargo of Prudhoe Bay crude oil. The oil would eventually impact more than 1,100 miles of non-continuous coastline in Alaska, making the Exxon Valdez the largest oil spill in U.S. waters at the time. (Photo courtesy NOAA)


WASHINGTON, DC, January 2, 2015 (ENS) – As of January 1, 2015 single-hull oil tankers are no longer allowed in U.S. waters.

The Oil Pollution Act of 1990, passed after the disastrous 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, required that all new tankers and tank-barges be built with double hulls to prevent similar oil spills.

Exxon Valdez
On March 24, 1989, the tanker Exxon Valdez ran aground on Bligh Reef in Prince William Sound, Alaska.  The  resulting 11 million gallon oil spill affected more than 1,100 miles of  coastline, making it the largest spill in U.S. waters at the time. (Photo courtesy NOAA)

For the first 25 years after the law was passed, single-hull tankers were still allowed to operate, but now those tankers are at the end of their operational lives and can no longer carry oil as cargo in U.S. waters.

The National Oceanic and Atmospheric Administration, NOAA, says the double-hull requirement was phased in gradually “because of the difficulty of converting existing single-hull tankers to double hulls, and retiring the single-hull tankers more rapidly would have been a major disruption to world shipping.”

The January 1, 2015 deadline did not bring about a major change because most of the tankers calling on U.S. ports have had double hulls for years.

In some collisions involving these double-hull tankers, not a drop of oil was spilled.

Twenty years after the Exxon Valdez oil spill, for instance, the Norwegian tanker SKS Satilla collided with a submerged oil rig in the Gulf of Mexico. The collision tore a huge hole in the tanker’s side, but none of the 41 million gallons of crude oil on board was spilled.

But single-hull tankers have spilled oil in the years since the Oil Pollution Act became law.

In 2004, the Cyprus-registered tanker Athos I struck a submerged anchor in the Delaware River while preparing to dock at a refinery in Paulsboro, New Jersey. The spill of 265,000 gallons of heavy crude oil fouled the river near Philadelphia, Pennsylvania.

For vessels with a single hull, one plate of steel is all that separates the oil on board from the ocean. If the hull is punctured from a collision or grounding, an oil spill is likely to occur.

A ship with a double hull has two plates of steel with empty space between them, essentially a hull within a hull. The second hull creates a buffer zone between the ocean and the oily cargo.

Damage to the single-hull Cosco Busan (Photo courtesy U.S. Coast Guard)

Although they are likely to prevent oil spills, the double hull requirements apply only to tankers and tank barges. Container ships, freighters, cruise ships, and other types of vessels are still built with single hulls. While these ships carry a lot less oil than a tanker, a large non-tank vessel can still carry a lot of fuel oil, and some have caused some big spills.

For instance, when the single-hull cargo ship Cosco Busan, operated by Fleet Management Ltd of Hong Kong, struck the San Francisco-Oakland Bay Bridge in November 2007 it spilled 53,569 gallons of bunker fuel oil into the San Francisco Bay.

The spill fouled beaches from the Marin Headlands to San Mateo County, killed nearly 7,000 birds and wiped out as much as 29 percent of the spawning herring that winter.

Double hulls don’t prevent all oil spills from tankers, NOAA acknowledges, but the design has been credited with reducing the amount of oil spilled, especially during low-speed groundings and collisions.

In 1992, two years after the Oil Pollution Act, the International Convention for the Prevention of Pollution from Ships, called the MARPOL Convention, was amended to require all newly built tankers have double hulls. MARPOL has been ratified by 150 countries, representing over 99 percent of merchant tonnage shipped worldwide.

Other pollution prevention requirements for shipping also took effect on January 1.

Sulfur Content of Fuel Oil Lowered

Ships trading in designated emission control areas will have to use on board fuel oil with a sulfur content of no more than 0.10 percent, down from the limit of 1.00 percent in effect until December 31, 2014.

The stricter rules come into effect under MARPOL regulation 14, which covers emissions of sulfur oxides (SOx) and particulate matter from ships. These requirements were adopted in October 2008 by consensus and entered into force in July 2010.

The SOx emission control areas are: the Baltic Sea area; the North Sea area; the North American area covering designated coastal areas off the United States and Canada; and the United States Caribbean Sea area around Puerto Rico and the U.S. Virgin Islands.

Outside the emission control areas, the current limit for sulfur content of fuel oil is 3.50 percent, falling to 0.50 percent on and after 1 January 2020. The 2020 date is subject to a review, to be completed by 2018, as to the availability of the required fuel oil. Depending on the outcome of the review, the date the rules take effect could be deferred to January 1, 2025.

Ships may also meet the SOx requirements by using gas as a fuel or an approved equivalent method, for example, exhaust gas cleaning systems or scrubbers.

Shipping Industry Lifts Objections to Ballast Water Management Treaty

Finally, the global trade association for merchant shipowners, the International Chamber of Shipping, ICS, has modified its stance towards the ratification by governments of the International Maritime Organization Ballast Water Management Convention, which has still not yet entered into force having been adopted more than 10 years ago.

The bulk carrier Hanjin Tacoma Port Hedland discharges ballast water while being loaded with coal at Kooragang Island Coal Terminal, Newcastle Harbour, New South Wales, Australia, Oct. 2010 (Photo by Doug Beckers)

The Ballast Water Management Convention is a treaty intended to protect local ecosystems from the impact of invasive species carried inadvertently in ships’ ballast water.

Water is used as ballast to stabilize vessels at sea. While ballast water is essential for safe and efficient modern shipping operations, it may pose serious ecological, economic and health problems due to the many marine species carried in ships’ ballast water. These include bacteria, microbes, small invertebrates, eggs, cysts and larvae of various species.

When the ballast water is dumped in a ship’s destination waters, the transferred species may survive to establish a reproductive population in the host environment, becoming invasive, out-competing native species and multiplying into pest proportions.

“The spread of invasive species is now recognized as one of the greatest threats to the ecological and the economic well being of the planet,” the IMO acknowledges. “These species are causing enormous damage to biodiversity and the valuable natural riches of the Earth upon which we depend. Direct and indirect health effects are becoming increasingly serious and the damage to environment is often irreversible.”

In December, the ICS said it will no longer actively discourage governments from ratifying the Ballast Water Management Convention, so that it can enter into force sooner rather than later. Once the treaty takes effect, amendments to the Convention requested by the shipping industry can be adopted and implemented by governments.

The ICS discouraged ratification of the treaty due to concerns about the lack of robustness of the approval process for expensive new treatment equipment, the criteria to be used for sampling ballast water during Port State Control inspections, and the need for “grandfathering” of equipment already in place or about to be fitted on ships.

Copyright Environment News Service (ENS) 2014. All rights reserved.


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