The Coulombi Egg Oil Tanker - The M/T 'Prestige' Incident 2002-2016
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M/T Prestige

Structural Failure caused Ballast Tank Flooding and heavy Listing

The M/T Prestige suffered a fracture in the side shell on 14 November 2002 during a spell of very severe weather outside Spain. The Master aboard, Captain Apostolos Mangouras, was not responsible for it.

The M/T Prestige was a 1976 built Pre-Marpol single hull crude oil tanker that had later been converted only to carry crude and products oil in dedicated cargo tanks and to use some wing tanks for segregated ballast. Cargo in the remaining wing tanks could only be part loaded for hydrostatic balance. She was 26 years old.

Photo Anders Björkman

Big cracks inside a ballast tank

At the time of the accident the M/T Prestige carried 77 000 tons of heavy fuel oil (products) and the segregated ballast wing tanks were empty. The cargo wing tanks were part loaded for hydrostatic balance. Very little or no cargo oil spilled out at this time. The damage may have looked like the picture above right! I took it myself inside the side ballast tank of a damaged tanker similar to M/T Prestige. I was an expert of finding cracks in tankers then, so they could be repaired in port.

Single hull oil tankers have a fair amount of structural redundancy, if there is a single fracture in, e.g. the side shell. The fracture causes leakage - oil may spill out (this will not happen to a Coulombi Egg tanker - with a crack in the side shell of a lower side cargo tank all oil will be pushed up into an undamaged ballast tank - The magic Egg!) or water may flood an empty ballast wing tank - and generally the local and global stresses are reduced. The fracture will of course grow due to the external wave forces, more cracks may form, but usually you have time to take preventive action.


The preventive action is evidently to immediately seek a calm port of refuge, where the cargo can be transferred , offloaded, to another tanker.

When the accident - the fracture in the side shell followed by flooding of an empty ballast wing tank - took place the tanker immediately informed the Spanish authorities. The Spanish authorities unfortunately did not understand that a safe port of refuge was the only solution.

Spanish Authorities caused the Oil Spill

They refused the loaded tanker a port of refuge and ordered it further out to sea. The result could only be what followed, even if the heavy weather spell calmed out. The fractures in the tanker side structure extended in all directions and on the 18 November about 40 meters of the complete shell shell and 8-10 meters width of the main deck fell off the tanker. Probably the same part of the bottom fell out. Then the global strength of the hull beam was severely reduced and the fractures could easily develop across the full beam - cargo oil started to leak: on the 19 November in the morning the tanker broke into two halves and soon both halves and 77 000 tons were lost. This product (heavy) oil is now slowly leaking out and will pollute the Spanish and French coasts for several years.

Capt Mangouras, the Master of the M/T Prestige was arrested by Spanish authorities immediately upon arrival ashore accused of causing the oil spill. He spent 83 days in prison and was only released (and put into house arrest) upon payment (by the London P&I club) of bail amounting to 3.000.000. Evidently the Master could not himself pay the enormous bail! As the Master evidently did not cause the oil spill, the Spanish authorities had then to delay any court proceedings ... for almost 10 years! See end of this article.

Double Hull not the Solution

It is widely suggested that double hull tankers will prevent what happened to the M/T Prestige. This is not certain. Double hull tankers have less structural redundancy than single hull tankers and, which is worse, four times more structural surfaces in the ballast spaces (the double hull) to protect against corrosion. Today one coat of epoxy coating is the standard protection; but many 1992-1996 built double hull tankers have already lost their protective coatings in the ballast tanks and have started to corrode. In addition the local and global stresses are generally higher in the double hull structure. A fracture in the side shell of a double hull tanker loaded with product oils will thus result in a similar accident as the M/T Prestige.

It must be recalled that double hull and alternative design (the Coulombi Egg is the only alternative!) was mandated by the IMO 1992 to provide better protection than single hull in collisions and groundings only. Protection against structural failures/damage was not considered and there is nothing to say that double hull has better structure than single hull - rather the opposite! Only the Coulombi Egg tanker has better structure than single (and double) hull.

The Accident Investigation

What caused the M/T Prestige structural failure? We are told that major steel repairs had been carried out 18 months before the accident. The steel repairs require a lot of manual welding and this writer thinks that some defects were introduced via the repair welding, e.g. bad preparation of the welding. This may later cause small fractures, etc. Actually, small fractures occur all the time in oil tanker steel structures and they can only be spotted by regular, visual inspections. If a fracture occurs and an empty ballast tank is flooded or a loaded cargo tank starts to leak oil - these are frequent events - the only solution is evidently to seek a calm port of refuge. The writer has 1973-2006 assisted many tanker owners to avoid oil spills from damaged single - or double - hull tankers and it is why he has developed the Coulombi Egg tanker. The Prestige accident shall be investigated by the Bahamas Authorities as per IMO Resolution A.849(20). Spain, France, Greece and other countries have the right to attend as interested parties/states. It will be an interesting investigation as Spain decided to arrest the Greek Master of the Bahamas flag tanker. Anyway - the investigation shall identify the circumstances of the casualty and establish the causes and contributing factors so that similar incidents are prevented in the future. It should be quite easy - the circumstances? - the tanker suffered leakage and a port of refuge was refused - the causes? - a fracture developed in the tanker structure, the fracture was permitted to extend so that the tanker broke in two - preventive measures? - better quality control of structural tanker repairs, more reliable surveys and quality control, availability of ports of refuge, better oil tankers! Evidently a Coulombi Egg tanker would not have split like the Prestige.

The Coulombi Egg Tanker is the only Solution

The Coulombi Egg tanker is superior to both single and double hull as described on the page links upper left. First of all there is 70% less structure in the ballast spaces subject to corrosion. Second there is a two-tiers mid-height deck inside the tank body adding extra redundancy in case of a fracture in, e.g. the side shell. But the risk for fractures in the side shell is reduced; the area at risk - below the waterline and the neutral axis (half-depth, D/2, of the tanker) is easy to inspect during loaded voyages (from the mid-height deck in the top side ballast tank).

The Coulombi Egg tanker is approved by the IMO since 1997, even if the IMO does not make much publicity about it - as good as or better than double hull as it provides much better collision protection and spills much less oil in groundings. It is also much safer than double hull - easier to ventilate and inspect ballast spaces (no double hull).

The Coulombi Egg tanker has also solved the problem of inadvertently transporting aquatic organisms from one part of the world to another in its ballast water. The ballast water is always carried above the (ballast) water line and it can easily be dropped out by gravity during the voyage and replaced by ocean water. You can even go down inside the ballast tank and wash out all sediment. This is evidently impossible in ordinary single or double hull tankers.

Double Hull Tankers are not the Solution to prevent future 'Prestige' Type Spills

There is no guarantee that double hull tankers will corrode and fracture less than single hull - rather the opposite. Anybody stating that double hull solves the problem does not know what they are talking about. Old single hull tankers are today subject to Condition Assessment Schemes, CAS, and/or Enhanced Survey Procedures, CAP. Both manadate close-up survey of about 100% of the structure in the ballast spaces and 30% of the total structure in the cargo spaces - a very big and difficult job - and everbody knows that you cannot possibly spot all cracks. Double hull requires even more close up-survey as the structure in the double hull ballast space has increased three times.

The only - and the best - solution is the IMO approved Coulombi Egg tanker.


'Prestige' Master and officers in dock 10 years after sinking (Oct 19 2012)

Some 10 years after the sinking of the tanker 'Prestige' off the Spanish coast, four men, including the vessel's Master, went on trial this week (October 19 2012) in a northern Spanish Court.

The sinking was claimed to have caused the worst oil slick in Spain's history, as 50,000 tonnes of fuel oil was dumped into the sea.

The first day of the trial, held at an exhibition centre in the northern city of La Coruna, was dominated by procedural questions, with the accused only expected to take the stand in November.

Apostolos Mangouras, 78, the 'Prestige's' Greek Master, is charged alongside two other officers and a Spanish official over the oil spill, which polluted thousands of kilometres of beaches in Spain, Portugal and France.

Prosecutors are demanding 12 years' jail for Mangouras, who is charged with harming the environment along with Greek chief engineer Nikolaos Argyropoulos and first mate Irineo Maloto, a Filipino who was not apprehended.

The fourth defendant is Jose Luis Lopez-Sors, head of the Spanish merchant navy at the time, who ordered the ship out to sea when it was leaking the fuel oil.

Mangouras attended the opening session of the trial along with Argyropoulos and Lopez-Sors.

According to AP news wire, environmental groups complained that key people responsible for the disaster were not being tried and warned that the lessons from the disaster had not been learnt.

Spanish Prime Minister Mariano Rajoy, who was deputy prime minister at the time of the accident, is among those who should be held accountable for his government's handling of the accident, they said.

Spanish non-government group Environmentalists in Action also said charges should be brought against ABS, the tanker's class society.

The total cost of the environmental damage caused by the oil slick has been calculated at more than 4 bill, most of it for the Spanish state.

'Prestige' leaked 50,000 tonnes of fuel into the Atlantic after it sank off northern Spain. It took on water in a storm on 13th November 2002, and drifted for six days before breaking up and sinking.

After three days of procedural matters this week, the defendants are due to make their first appearance in the trial on 13th November, the 10th anniversary of the disaster.

The trial is due to last until May 2013 and will hear testimony from 133 witnesses and 100 experts, the Court said."


But will we ever know what caused the oil spill, i.e. why the tanker started to leak oil. Did the Master Mangouras make the hole in the tanker himself? Has the 'Prestige' Spanish accident investigation ever identified the real circumstances of the casualty and established the proximate cause of the incident and any contributing factors so that similar incidents are prevented in the future? The answer is simple. No. I wonder what the 133 witnesses and 100 experts have to add?

I was wrong!

November 15 2013 we finally learnt:

A Spanish court has found the crew of the tanker ‘ Prestige ‘ and the Spanish Merchant Navy not guilty for criminal responsibility of the sinking of the oil tanker on 13th November, 2002.

Prestige’ sank off Spain’s northwestern coast and polluted thousands of miles of coastline and beaches in Spain, France and Portugal - prompting Spain to close its fishing grounds for about six months. The single-hull tanker was transporting about 77,000 tonnes of heavy fuel oil.

Initially, the ship’s Master Apostolos Mangouras asked for a place of refuge for the tanker, which had a crack in its hull. However, the Spanish authorities denied his request and instructed him to take his ship further out to sea. The French and Portuguese governments also denied any assistance.

On 19th November following a storm, the hull broke in half the cargo entered the sea off Spain’s coast. Mangouras was taken into custody for 'not co-operating' with salvage crews and causing environmental damage.

After an 11-year judicial investigation, the Galician region's high court said that the disaster was partly due to the 26-year-old tanker's poor state of repair. Spain was also unsuccessful in suing ABS for the condition of the ship.

Three judges of the Galician Spanish High Court concluded it was impossible to establish criminal responsibility and Capt Mangouras, Chief Engineer Nikolaos Argyropoulos and the former head of Spain's Merchant Navy, Jose Luis Lopez, were found not guilty of crimes against the environment.

Lopez was the only government official charged in the case. Mangouras was found guilty of a lesser charge of disobedience and given a nine-month suspended sentence.

"The Spanish authorities had the correct advice to evaluate the hypothesis on whether, or not the tanker should be moved away from the coast," said Chief Justice Juan Luis Pia, as he relayed the verdict and sentence in a televised court hearing.

The Judges said the leak was caused by deficient maintenance, which the crew did not know about, the newswires reported.

What a pity that the port of refuge was denied. Therefore never tell shore that your tanker is leaking when seaking a port of refuge. Better tell that you have engine/generator problems or that a seaman is ill.

However, September 2015 Spain's state prosecutor asked the Spanish Supreme Court to overturn the lower court's decision to acquit three men over the 2002 Prestige tanker spill, one of Europe's worst environmental disasters. And January 2016 the Supreme Court agreed!

The Master was again found guilty of the oil spill and sentenced to two years in prison.

This was clearly against the DIRECTIVE 2009/18/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 23 April 2009 para (9) which says: 

Seafarers are recognised as a special category of worker and, given the global nature of the shipping industry and the different jurisdictions with which they may be brought into contact, need special protection, especially in relation to contacts with public authorities. In the interests of increased maritime safety, seafarers should be able to rely on fair treatment in the event of a maritime accident. Their human rights and dignity should be preserved at all times and all safety investigations should be conducted in a fair and expeditious manner. To that end, Member States should, in accordance with their national legislation, further take into account the relevant provisions of the IMO guidelines on the fair treatment of seafarers in the event of a maritime accident.

So never ask for a place of refuge when your tanker leaks. Ask for a place of refuge beacuse you have a generator problem or similar.

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