Russia-flagged oil tanker, the Volganeft-139, split apart in November when struck by a 67mph (108km/h) storm with 16ft (5m) waves while at anchor between the Azov and Black Seas, releasing 2,000t of fuel oil into the Kerch Strait and risking the lives of its 13 crewmembers.

The Soviet-era tanker was reportedly not designed to transport oil anywhere but by river – let alone to withstand violent storms. Accidents, however, aren’t restricted to ‘outsider’ players. A month later, the Hong Kong-registered 146,000t tanker Hebei Spirit collided with a barge-mounted crane near South Korea, leaking 10,000t of crude into the sea.

The International Tanker Owners’ Pollution Federation (ITOPF) says about 10,000 accidental oil tanker, combined carrier or barge spills have occurred since 1970, and 84% were spills of less than 7t.

The average number of large spills (more than 700t) a year in the 1990s was less than a third of that in the 1970s. In 2006, just four spills of more than 700t were recorded – down from 29 in 1970. The few very large spills represent a high percentage of the total oil spilt. For example, 1990 to 1999 saw 358 spills over 7t, totalling 1,138 million tons, but 73% of that was spilt in 3% of incidents.

Accidents will happen. But what can be done to reduce their likelihood? And how might their severity be lessened?


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Dr David Santillo, a University of Exeter Greenpeace Labs marine biologist, said the Volganeft-139 was, like many ships that have caused devastating spills in the past, a single-hulled tanker. “The Erika spill off France in 1999, the Prestige spill off Spain in 2002 and even the [2007] spill in Korean waters may have been avoided had the tankers been double-hulled,” he said.

The International Maritime Organisation (IMO), which oversees shipping safety and environmental performance, has mandated that new tankers over 5,000 deadweight-tons (dwt) be double-hulled from July 1993.

“About 10,000 accidental oil tanker, combined carrier or barge spills have occurred since 1970.”

“Single-hulled tankers are being phased out,” Santillo said, according to the International Convention for the Prevention of Pollution from Ships (MARPOL) Annex I. The EU also recently banned all single-hulled tankers carrying heavy grades of oil from entering European ports.

“Phase-out dates range from 2005 to 2010. By 2010, therefore, there should be no more single-hulled tankers in use for carrying oil or oil-derived products [in the EU],” he said.

Santillo warns though, that double-hulled construction will not stop all spills, especially if tankers are in poor condition or suffer large-scale structural damage, but they clearly can prevent many. “With a single hull, there is no second line of defence. If the hull is penetrated to any degree, a spill is inevitable. That has consequences for safety of life at sea as well as for the environment and the economy,” he said.

Dr Peter Swift, managing director of the International Association of Independent Tanker Owners (INTERTANKO), suggested in a statement that the global tanker fleet is being upgraded at a good pace. “Over recent years, tanker owners have invested an average of nearly $32bn (£16.1bn) a year in new ships and today over 75% of the internationally traded fleet is double-hulled,” he said.


Double-hulled tankers are not the only alternative. The IMO has also approved the Coulombi Egg design by safety-at-sea consultant and naval architect Anders Björkman of France-based company Heiwa.

Björkman claims oil spills due to structural failures and fire or explosion could happen to double-hulled tankers earlier than with single-hulls – as the double-hull is made of thinner steel and is under more structural stress. The Coulombi Egg design, Björkman alleges, is more robust because of its two-tiered, mid-height deck structure and ease of maintenance and inspection – increasing safety at a lower cost, particularly for VLCC and Suezmax crude tankers.

IMO records reveal the Coulombi Egg features a series of centre and wing tanks, divided by horizontal bulkheads. Upper wing tanks form ballast tanks or emergency receiver tanks for cargo if the lower tanks are fractured.

“The EU recently banned all single-hulled tankers carrying heavy grades of oil from entering European ports.”

Hydrostatic loading principles mean that if a lower side hull is breached, the pressure from outside would exceed that from the oil inside so seawater can flow in, pushing the oil upwards through non-return valves into ballast tanks.

Side ballast tanks also act as crumple zones in the event of a collision. Also, if a lower cargo hull is breached and cargo pushed into ballast tanks, the tanker would list away from the damaged side.

Unfortunately, the alternative design hit a roadblock in 1998 when it came to convincing the US Coast Guard (USCG). According to industry publication Alexander’s Oil & Gas Connections, USCG did not accept the IMO’s weighting of various factors in its guidelines.

“The coast guard has correctly noted that the majority of spills in US waters result from low-impact collisions and groundings and that the double-hull design, therefore, would provide maximum protection,” the publication stated. “Once penetrated, however, there is no accounting for potentially major oil outflow, structural damage to the vessel, the danger of fire and explosion, loss of stability or salvage problems.”

The report said that mid-deck and Coulombi Egg designs should be much better than the double hull at reducing mean and extreme discharges. “The US has shut the door to any further consideration of alternative designs. This means that few, if any, naval architects worldwide have any motivation to find better ways to design tankers,” the report added.


Will tanker upgrades happen quickly enough in the face of stretched resources? For the next quarter or a century, fossil fuels including oil and gas will probably still supply most of the world’s energy needs.

UK oil and gas faces increasing competition pressures, but maintaining production as oil and gas fields shrink and disperse. Development and operating costs are predicted to keep rising for the foreseeable future. There’s a shortage of skilled staff to man the ships. Oil and gas can be piped – but that can be even more expensive and offers its own technological challenges.

“The Coulombi Egg design is more robust because of its two-tiered, mid-height deck structure.”

Meanwhile, government and industry partnership PILOT wants the industry to stay self-sufficient and maintain the world’s top safety standards, while producing three million barrels of oil-equivalent a day beyond 2010, with sustained investment of £3bn a year and £1bn additional revenue from new businesses on top of 100,000 more jobs. That’s quite some goal – and must be achieved in the face of increasing competition from cheaper, non-EU shipping that doesn’t adhere to EU
standards and practices.


Operators can reduce the spill volume in case of accident by improving tanker design. Or they can reduce accident numbers and severity by improving overall shipping safety through onshore and offshore initiatives. The European Maritime Safety Agency (EMSA) will have a strengthened oil recovery vessel team for the Atlantic and Mediterranean, via a network of companies, operational by mid-2008.

“Now that we have this third set of vessels contracted, EMSA is in a better position to provide ‘top-up’ response vessels relatively quickly should pollution disasters occur in the future,” said EMSA executive director Willem de Ruiter.

“We now have a number of vessels, including back-ups, throughout the Baltic, Atlantic and Mediterranean areas. The network is nearing completion. Next year, we will have to close remaining loopholes, including the Black Sea. We are looking into the best way of doing this.”

Regulation is always under review too. There will be more revisions to MARPOL, its annexes and associated condition assessment schemes, which regulates oil tanker design and construction, onboard equipment, piping and pumping, operational discharge of oil from all ships, shore reception facilities, tank cleaning, shipboard emergency plans and response in case of damage.

MARPOL could be leveraged to improve shore-based reception facilities and national implementation and enforcement policies. Revised condition assessment schemes might address fears about double-hull space corrosion as the first crop of these tankers hits the 15-year-old mark, according to IMO.

Tankers already have to undergo more stringent inspection and adhere to stricter safety procedures than other marine vessels – such as under the International Regulations for the Prevention of Collisions at Sea (COLREGS) 1972.

“Development and operating costs are predicted to keep rising for the foreseeable future.”

The IMO in October emended rules relating to the provision of mobile satellite communication services at sea, further development of goal-based standards for new ship construction and discussion of maritime security issues. At the same meeting, the IMO mandated the introduction of a new long-range identification and tracking (LRIT) system as well.

From 1 July 2008, IMO will require all new ship radars to meet revised standards.


ITOPF’s Moller says 13 – or 2.2% – of oil spills from tankers of seven tonnes or heavier from 1987 – were from UK-flagged ships (which doesn’t mean they were UK-owned).

According to the IMO, disaster prevention measures are working. Just 10% of all human sources of marine pollution in 2002 were from activities at sea, down 2% from 1990. That’s despite shipping market analysis by Fearnleys that suggests world seaborne trade surged from 13,856 billion ton-miles in 1986 to 30,686 billion ton-miles in 2006 – with oil and petroleum products rising 106% to 12,151 billion ton-miles.

“I have heard that less than one teaspoon of oil is spilt for every million gallons transported by ships. Put another way, some 99.9996% of all oil transported by sea is delivered safely and without impact on the marine environment,” an IMO spokesperson said.