A Final Farewell to Single Hull Oil Tankers, by Marex

Single Hull 1

January 1, 2015 marks a major milestone in preventing oil spills.

That date is the deadline which the landmark Oil Pollution Act of 1990 (OPA-90) specifies for phasing out single-hull tankers in U.S. waters. That act, passed after the 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, required that all new tankers and tank-barges be built with double hulls.

Recently constructed single-hull tankers were allowed to operate, but 25 years after the Exxon Valdez, those vessels are now at the end of their operational life and will no longer be able to carry oil as cargo.

The requirement was phased in gradually because of the difficultly 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.

Counting Down to a New Era

There won’t be a dramatic change-over on New Year’s Eve; most of the tankers calling on U.S. ports have had double hulls years before this deadline. However, one ship which was not switched over to a double hull soon enough was the tanker Athos I. This ship, carrying 13.6 million gallons of heavy crude oil, struck a submerged anchor in the Delaware River and caused a relatively large, complicated oil spill near Philadelphia, Pennsylvania, 10 year ago.

Single Hull 2

Left, the single-hull tanker Exxon Valdez ran aground on Bligh Reef in Prince William Sound, Alaska, March 24, 1989, spilling 11 million gallons of crude oil. This spill inspired the Oil Pollution Act of 1990, which required the phase out of single-hull tankers and tank-barges by January 1, 2015. Right, another single-hull tanker, the Athos I, hit a submerged anchor in the Delaware River in 2004 and spilled more than 263,000 gallons of heavy crude oil. (U.S. Coast Guard)

In 1992, two years after the Oil Pollution Act, the International Convention for the Prevention of Pollution from Ships (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.

Stay out of Trouble by Going Double

So, what is the big issue around single vs. double-hull ships? Historically, tankers carrying oil were built with a single hull, or single shell.

While we measure oil in barrels, it is not actually shipped that way. Instead, oil is pumped into huge tanks that are part of the structure of tankers and barges. For vessels with a single hull, one plate of steel is all that separates the oil on board from the ocean. If the hull were punctured from a collision or grounding, an oil spill is pretty much guaranteed to follow. On the other hand, a ship with a double hull has two plates of steel with empty space in between them. The second hull creates a buffer zone between the ocean and the cargo of oil.

Naval architects have debated the merits of various hull designs in reducing oil spills, and using a double hull, essentially a hull within a hull, was selected as the preferred vessel design.

However, the double hull requirements only apply 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 pretty big spills, including the 2007 oil spill caused by the cargo ship Cosco Busan in San Francisco Bay.

Aeral photo of the Cosco Dusan. Coast Guard Photo By CWO Scott Epeprson

The cargo ship Cosco Busan lost 53,000 gallons of fuel oil when the single-hull ship hit the San Francisco-Oakland Bay Bridge in 2007. (U.S. Coast Guard) 

Of course, double hulls don’t prevent all oil spills from tankers either, but the design has been credited with reducing the amount spilled, especially in the cases of low-speed groundings and collisions.

And some pretty spectacular collisions have resulted in double-hull tankers not spilling a drop.

Twenty years after the Exxon Valdez oil spill, the Norwegian tanker SKS Satilla collided with a submerged oil rig in the Gulf of Mexico. The collision tore a huge hole in the side of the oil tanker, but, thankfully, none of the 41 million gallons of crude oil it had on board was spilled. Source: http://response.restoration.noaa.gov/

Update: Singapore: Oil Tanker and Bulk Carrier Collide, by Marex


A collision has occurred between the oil tanker Alyarmouk and the bulk carrier Sinar Kapuas north-east of Pedra Branca in Singapore.

The Maritime and Port Authority of Singapore (MPA) received notification of the collision on January 2. 

The Libyan-registered Alyarmouk sustained damage to one of its cargo tanks, and an estimated 4,500 tons of Madura crude oil was spilled from the tanker.

Taking into account the weather and tidal currents, patches of oil may affect the northern parts of the island of Bintan. 

As part of standard operating procedures for joint oil spill combat in the Straits of Malacca and Singapore, MPA has notified the Malaysian and Indonesian Authorities.

Two oil spill response companies have been activated to combat the spill. The companies have deployed four craft equipped with dispersants, oil booms and skimmers to the site.

The two vessels involved in the collision are currently safely anchored and in stable condition, reports the MPA. There is no report of injury, and traffic in the port and the Strait of Singapore remains unaffected. MPA is investigating the cause of the collision.

After Deadly Blaze, Burnt-out Ferry Towed to Italy, by Marex

Ferry Fire

Tugboats hauled the burnt-out hulk of a ferry that caught fire off the coast of Greece into a southern Italian port on Friday, opening the way for an investigation into the blaze that killed at least 11 people.

Listing visibly to starboard, the Norman Atlantic multi-deck car-and-truck ferry docked in the port of Brindisi in the early afternoon, still smoldering.

The fire broke out on Sunday on one of the lower garage levels and left the vessel drifting without power in stormy seas. It took Greek and Italian rescue teams 36 hours to evacuate 477 passengers and crew from the ship amid strong winds.

Most were winched into helicopters from the upper deck of the ship as the blaze raged below, but dozens may still be missing, possibly including unauthorized migrants not listed on the ship’s manifest, Italian officials have said.

“Given that the ship was indisputably carrying illegal migrants who were probably hidden in the hold, we fear that we’ll find more dead people once we recover the wreck,” Giuseppe Volpe, the Italian prosecutor leading the investigation into the cause of the fire, said earlier this week.

Reports of the number of missing have varied widely. The Greek coastguard said on Thursday that 18 were still unaccounted for. Volpe said on Friday the number of people missing was around 10-15, having previously said it may be as high as 98.

Investigators will only be able to descend to the lower decks once the vessel is fully secured but black box recorders were recovered and will be examined for clues, said officials.

In his end-of-year address, Italian Prime Minister Matteo Renzi praised the rescue effort and complimented the ship’s captain, Argilio Giacomazzi, for staying on board until the ship was fully evacuated.

But several rescued passengers have criticized the handling of the emergency.

Leonidas Constantinidis, a Greek lorry driver with a bandaged arm and apparent burn marks on his face, told Reuters he had jumped overboard to save himself and was picked up by a nearby merchant ship.

“Where I was I did not hear any siren, any alarm. Nothing seemed to work, the fire sprinklers, the fire extinguishers, nothing was working,” Constantinidis said.

Six people — the captain, three crew members, the ship’s operator and its owner — are under investigation by a Bari court for multiple manslaughter and causing a ship disaster, judicial sources said on Friday. By Gabriele Pileri (C) Reuters 2014.

IMO Sec-Gen Calls for Action on Passenger Ship Fatalities, by Marex



As the new year rang in, IMO Secretary-General Koji Sekimizu released the following statement regarding the large amount of maritime casualties in 2014.

“The incidents over the holiday period involving the vessels Norman Atlantic and Blue Sky M have reminded us once again how perilous a voyage at sea can be. Although fundamentally different in nature, both saw human lives placed at risk in difficult and challenging circumstances. My deepest condolences go to all those who have been caught up in these incidents, especially those who have lost their loved ones. I should also like to express my sincere appreciation for all those who have been, and continue to be, involved in the rescue operations, notably the Italian and Greek authorities, and especially the two Albanian seafarers who tragically lost their own lives during the operation to secure the stricken ferry Norman Atlantic. As we begin the new year, we must all rededicate ourselves to ensuring the safety if all those who live, work and travel on the world’s oceans.

“2014 will be remembered as another year of very serious maritime casualties involving passenger ships, with the tragedy of Sewol and the fire of Norman Atlantic. IMO must take action to investigate these maritime accidents and improve safety standards of passenger ships. In this context, I urge IMO member governments to review the current level of safety standards of passenger ships at the Maritime Safety Committee in June and discuss how we could strengthen our system and prevent such very serious maritime accidents involving passenger ships in future. I urge the authorities of Italy and Greece to accelerate the process of the casualty investigation and submit findings to IMO as soon as possible.

“On the issue of maritime migrants on board Blue Sky M, the international community must take action now to address the people-smugglers that are behind this sort of migration and consider ways to prevent similar incidents of sending hundreds of migrants on unlawful and unregulated sea passages. As I declared at the High Level Dialogue organised by the UN High Commission for Refugees in December, I am convening an inter-agency meeting at IMO Headquarters in March to address smugglers behind maritime migrants and consider effective measures to prevent migrants taking unlawful and unregulated sea passages. The international community must take action to address maritime migration in the twenty-first century.”