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. Iwas 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 saferthan 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.
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 Spains 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 ships 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 Spains 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.
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.