The bulk carrier
was first developed to carry dry cargoes, which are shipped in large quantities
and do not need to be carried in packaged form. The principal bulk cargoes
are coal, iron ore, bauxite, phosphate, nitrate and grains such as wheat.
bulk carrier Berge Stahl
of carrying such cargoes in bulk is that packaging costs can be greatly reduced
and loading and unloading operations can be speeded up. Before the Second
World War, however, there was no real demand for special bulk carriers. Seaborne
trade of all mineral ores only amounted to 25 million tons in 1937 and this
could be carried in conventional tramp ships (freight vessels).
By the 1950s,
however, movements of bulk cargoes were increasing. Very often ores and other
commodities were found far away from where they were needed and the most convenient
and cheapest way of shifting them was by sea. Companies in the United States,
Europe and increasingly in Japan began to build ships designed exclusively
for the carriage of cargoes in bulk.
As demand increased
and shipbuilding technology advanced so these ships tended to become bigger
in size and carrying capacity. This afforded the same economies of scale
that were to make the Very Large Crude Carrier (VLCC) so attractive to oil
tanker operators in the 1970s. Doubling the amount of steel used in constructing
a ship enabled the amount of carrying capacity to be cubed, yet the size of
the crew required did not increase greatly and other costs, such as fuel,
also rose relatively slowly, especially since speed was not vital to bulk
bulk carrier has evolved gradually but since the 1960s the standard design
has been a single hull ship with a double bottom, large cargo holds with hopper
tanks and topside tanks covered by hatches. As with crude oil tankers the
engine room, navigating bridge and accommodation areas are nearly always located
at the stern of the ship.
By the 1970s,
bulk carriers of more than 200,000 dead weight (dwt) were operating and rivalled
the VLCCs as the largest ships afloat. There are several other similarities
between bulk carriers and tankers, which help to explain the frequency with
which they are mistaken for each other. The simplest way of telling a bulk
carrier from an oil tanker is that the holds of the bulk carrier are covered
by hatches raised above the deck level, while the deck of the tanker is covered
with fuel pipes. A bulk carrier of 36,000 dwt may have five cargo holds while
one of 250,000 dwt may have as many as nine. Also, ships were being built
which could carry oil, ore or other types of dry bulk cargoes. This was done
to increase operational flexibility. One of the problems with the bulk trades
(as with oil transportation) is that ships normally carry cargo one way but
return in ballast because there is nothing to take back. However, oil/bulk/ore
(OBO) ships have never become as popular as dedicated bulk or oil carriers,
partly because their complexity increases building and operating costs.
carriers transport a high percentage of world trade - and in most cases they
do so safely. According to the International Association of Dry Cargo Shipowners
(Intercargo), in 1990-1994, 99.90% of dry bulk cargoes were delivered safely.
In the case of iron ore the figure
was 99.71% and for both grain and coal reliability was 99.97%.
The post-war boom in Japan led to
a huge increase in demand for raw materials and the ships on which to carry
them. Here a bulk carrier operated by K Line prepares to take on a cargo of
of cargo carried is enormous. In 1996, according to Intercargo, 1,092 million
tonnes of iron ore, coal, grain, bauxite and phosphates were carried by sea.
A further 703 million tonnes of products such as steel, cement, pig iron,
fertilizer and sugar were also shipped by bulk carriers.
products are carried on ships in bulk. Grains, such as wheat,
maize, millet and rye have been transported by sea for centuries - the wheat
trade between north Africa and Italy was a major economic feature of the Roman
Empire, for example. Since the last century, the grain trade has grown in
importance and much of it is carried by sea, often on long trans-Atlantic
or trans-Pacific voyages.
the International Grains Council, in 1996-1997 (July/June) total wheat trade
amounted to 91.3 million metric tons, with the biggest exporters being the
United States (26.5 million tons). Other exporters are Australia (17.4 million
tons) and Canada (17.0 million tons) while the biggest importers being Iran
(6.7 million tons), Egypt (6.2 million tons) and Japan (5.3 million tons).
In addition, 88.8 million tons of coarse grains including maize, millet and,
rye were shipped in 1996-1997, the largest exporters being United States (53.1
million tons), Argentina (10.6 million tons) and European Union (8.1 million
tons) and the largest importers being Japan (20.3 million tons), South Korea
(9.2 million tons) and Saudi Arabia (6.3 million tons). Total grains shipped
in the year 1996-1997 were therefore 180.1 million tons -- or just over 3,600
panamax-sized (50,000-dwt) shiploads.
grain was transported in sacks, but by the middle of the 20th century the
normal procedure was to carry it in bulk. It could be stored, loaded and
unloaded easily and the time taken to deliver it from producer to customer
was greatly reduced, as were the costs involved. However, there were problems.
Grain has a
tendency to settle during the course of a voyage, as air is forced out when
the individual grains sink (“sinkage”). This leads to a gap developing between
the top of the cargo and the hatch cover. This in turn enables the cargo
to move from side to side as the ship rolls and pitches. This movement can
cause the ship to list and, although initially the ship’s movement will tend
to right this, eventually the list can become more severe.
This picture shows what can happen
when a ship’s cargo shifts to one side. A list can develop which, in extreme
cases, can cause the ship to capsize.
In the worst
cases, the ship can capsize. This problem was well known and when the International
came into being in 1959 one of its first tasks was to consider new measures
for improving the safety of bulk carriers. These were incorporated into the
International Convention for the Safety of Life at Sea (SOLAS),
1960. This was a new version of a convention that owed its origins to the
Titanicdisaster of 1912. The new bulk carrier regulations were more advantageous
from an economic point of view than those adopted in SOLAS 1948 (which required
a more extensive use of increasingly expensive temporary fittings and/or bagged
grain) and many countries quickly put them into effect, even though the Convention
itself did not enter into force until 1965. However,
the new regulations still had some deficiencies as far as safety was concerned,
for during a period of four years, six ships loaded under the 1960 SOLAS rules
were lost at sea. IMO began looking at this problem early in 1963 and asked
masters of ships to contribute information to a broad study. Further studies
and tests showed that some of the principles on which the 1960 regulations
were based were invalid -- in particular, it was shown that the 1960 Convention
had underestimated the amount of “sinkage” which occurs in grain cargoes loaded
in bulk. This made the basic requirements of the Convention unattainable.
As a result, the IMO Assembly in 1969 adopted new grain regulations [resolution
A.184 (VI)], which became generally known as the 1969 Equivalent Grain Regulations.
over a three-year period showed that the 1969 Grain Equivalents were not only
safer but were also more practical and economical than the 1960 regulations
and, with slight amendments, based upon operational experience, they were
used as the basis of new international requirements which were subsequently
incorporated into the 1974 SOLAS Convention. Although grain was the only bulk
cargo to be given a special chapter in the 1960 SOLAS Convention, IMO also
developed an international Code of Safe Practice for Solid Bulk Cargoes (BC
Code), which was adopted in 1965. The Code has been updated at regular
intervals since then and is kept under continuous review by the Sub-Committee
on Dangerous Goods, Solid Cargoes and Containers. The practices contained
in the Code are intended as recommendations to Governments, ship operators
and shipmasters. Its aim is to bring to the attention of those concerned
an internationally-accepted method of dealing with the hazards to safety which
may be encountered when carrying cargo in bulk.
The codes that
are most relevant to the safety of bulk carriers are the revised BC Code and
a new mandatory International Code for the Safe Carriage of Grain in Bulk
(International Grain Code). Like the original grain rules, the Code is designed
to prevent the particular qualities of grain threatening the stability of
ships when it is carried in bulk. It applies to all ships - including existing
ships and those of less than 500 tgt (tons gross tonnage) - that carry grain
in bulk. Part A contains special requirements and gives guidance on the stowage
of grain and the use of grain fittings. Part B deals with the calculation
of heeling moments and general assumptions.
BC Code deals with three basic types of cargo: those which may liquefy; materials
which possess chemical hazards; and materials which fall into neither of these
categories but may nevertheless pose other dangers. The Code highlights the
dangers associated with the shipment of certain types of bulk cargoes; gives
guidance on various procedures which should be adopted; lists typical products
which are shipped in bulk; gives advice on their properties and how they should
be handled; and describes various test procedures which should be employed
to determine the characteristic cargo properties.
The Code contains
a number of general precautions and it is of fundamental importance that bulk
cargoes be properly distributed throughout the ship so that the structure
is not overstressed and the ship has an adequate standard of stability. Loaded
conditions vary according to the density of the cargo carried. The ratio
of cubic capacity to deadweight capacity of a normal ship is around 1.4 to
1.7 cubic metres per tonne and the ratio of volume of cargo to its mass is
known as the stowage factor. When high density bulk cargoes with a stowage
factor of about 0.56 cubic metres per ton or lower are carried, it is particularly
important to pay attention to the distribution of weight in order to avoid
excessive stresses on the structure of the ship.
All bulk cargoes
when loaded tend to form a cone. The angle formed between the slope of the
cone and the bottom of the hold will vary according to the cargo and is known
as the angle of repose. Some dense cargoes, such as iron ore, form a steep
cone while others - such as grain - have a much shallower angle. Cargoes
with a low angle of repose are much more prone to shift during the voyage
and special precautions have to be taken to ensure that cargo movement does
not affect the ship’s stability. On the other hand, the sheer weight of dense
cargoes can affect the structure of the ship.
with general precautions, the Code then goes on to deal with cargoes having
an angle of repose of 35 degrees or less and then with those where the angle
of repose is greater than 35 degrees. Cargoes with a low angle of repose
are particularly liable to dry-surface movement aboard ship. To overcome
this problem, the Code states that such cargoes should be trimmed reasonably
level and the spaces in which they are loaded should be filled as fully as
is practicable, without resulting in excessive weight on the supporting structure.
should be made for stowing dry cargoes that flow very freely, by means of
securing arrangements, such as shifting boards or bins. The Code says that
the importance of trimming as a means of reducing the possibility of a shift
of cargo can never be over-stressed. This is particularly true for smaller
ships of less than 100 metres in length. Trimming also helps to cut oxidation
by reducing the surface area exposed to the atmosphere. It also helps to
eliminate the “funnel” effect, which in certain cargoes, such as direct reduced
iron (DRI) and concentrates, can cause spontaneous combustion. This occurs
when voids in the cargo enable hot gases to move upwards, at the same time
sucking in fresh air.
The Code then
gives details of other dangers that may exist. Some cargoes, for example,
are liable to oxidation which may result in the reduction of the oxygen supply,
the emission of toxic fumes and self-heating. Others may emit toxic fumes
without oxidation or when wet. The shipper should inform the master about
any chemical hazards that may exist and the Code gives details of precautions
that should be taken.
Code gives details of the various sampling procedures and tests, which should
be used before transporting concentrates and similar materials and also contains
a recommended test procedure to be used by laboratories. There are seven
appendices to the Code, giving information about particular cargoes. A list
of cargoes, which may liquefy is contained in appendix A to the Code, for
example while appendix B gives an extensive list of materials possessing chemical
hazards. Some of the classified materials listed also appear in the International
Maritime Dangerous Goods (IMDG) Code when carried in packaged form, but
others become hazardous only when they are carried in bulk - for example,
because they might reduce the oxygen content of a cargo space or are prone
to self-heating. Examples are woodchips, coal and direct reduced iron (DRI).
Appendix C deals with bulk cargoes which are neither liable to liquefy nor
possess chemical hazards. More detailed information concerning test procedures,
associated apparatus and standards, which are referred to in the Code are
contained in appendix D. Emergency Schedules for those materials listed in
appendix B are contained in appendix E. Recommendations for entering cargo
spaces, tanks, pump rooms, fuel tanks and similar enclosed compartments are
shown in appendix F. Procedures for gas monitoring of coal cargoes are contained
in appendix G.
In 1990 the
IMO issued a circular (MSC/Circ.531), which warned against the risks of shifting
cargo and requested Member Governments to implement revised recommendations
for trimming cargoes that were included in the 1989 edition of the Code and
are intended to minimize sliding failures.
taken by IMO undoubtedly helped to solve many of the problems associated with
the carriage of bulk cargoes, such as cargo shift and the consequent loss
of stability. The number of accidents involving bulk carriers dropped during
the 1980s and it seemed to many observers that the general problem of bulk
carrier safety had been solved.
of a typical bulk cargo hold.
such as iron ore are extremely heavy and can exert tremendous pressure
on the ship’s hull. Homogenous loading as shown below, is usually adopted
for low density cargoes such as coal and grain, but may also be permitted
for high-density cargoes under certain conditions.
however, cargoes such as iron ore are carried in alternate holds.
a ship is floating in still water, there will be differences in the
forces exerted upon the hull, which have to be taken into account when
the ship is loaded.
loading can result in shearing pressures, while uneven loading can cause
the ship to “sag” or results in “hogging”.
Association of Classification Societies (IACS). Bulk Carriers Guidance and
Information on Bulk Cargo Loading and Discharging to Reduce the Likelihood
of Over-stressing the Hull Structure.
in 1990 the trend was dramatically reversed: 20 bulk carriers sank with 94
lives lost and in 1991, 24 sank with 154 dead.
This development was so dramatic and so unexpected that alarm bells began
to ring throughout the shipping world. It became increasingly apparent that
many of the bulk carriers lost - often without trace - had suffered from severe
structural damage. In some cases ships had simply broken apart like a snapped
pencil. What had gone wrong? And
what could be done to improve matters?
importance of age
There is no
doubt that there is a clear link between accidents and the age of bulk carriers.
All but two of the ships lost in 1990 were over 18 years old. In July 1995
the classification society Lloyd’s Register of Shipping published a table
giving details of accidents involving 88 bulk carriers between January 1990
and December 1994. Only three of the ships on the list were less than ten
years old and nearly half were over 20. What makes this so worrying is that
the average age of bulk carriers had been rising steadily - from under nine
years old in 1980 to more than 14 by 1995. The reason for this upward trend
is primarily economic. During the 1980s there was a glut of shipbuilding,
mainly because the industry greatly over-estimated the way in which trade
would develop. This was especially true of tankers, but it was true to some
extent of bulk carriers as well and when trade increased much more slowly
than had been forecast (and sometimes declined) the result was a fall in the
demand for ships. Some older ships were scrapped and others laid up waiting
the return of more favourable trading conditions. But throughout the period
there has generally been a surplus of unwanted ships and freight rates have
usually remained low. This has discouraged the construction of new tonnage
and has led shipowners and builders to explore new ways of cutting costs.
is potentially worrying. A survey of bulk carrier safety issued in July 1995
by the classification society Lloyd’s Register (entitled Bulk Carriers - an
Update) pointed out that “an historically critical age group for bulk carrier
casualties is from 14 to 18 years and that in three or more years’ time a
large proportion of bulk carriers in service will be in this age group unless
the age distribution is changed by, for example, a substantial scarpping programme.
of Bulk Carrier Losses, 1990-1997.
by Intercargo of bulk carrier losses showed that in30 cases the cause was
plate failure and water entering the hull. All the other causes added together
accounted for the other 76 sinkings.
economic reasons, there is little sign of such a mass scrapping taking place.
At the turn of the century, the great majority of the world’s bulk carrier
fleet have reached the danger point. More than half the world’s bulk carrier
fleet is already more than 15 years old and one third is more than 20 years
Corrosion and Fatigue
The main reason
why age is so relevant to shipping casualties is that corrosion and general
fatigue increase, as ships grow older. This is partly because of the stresses
to which the ship is inevitably subjected by routine operations, cargo handling,
weather and waves and partly to the effect of seawater on steel. Although
any water tends to causes metals such as steel to rust, seawater is much more
harmful than fresh water because it contains so much salt. The bulk carriers
used in the Great Lakes of North America, for example, frequently survive
to 50 or 60 years of age - up to three times as long as the average ocean-going
a serious problem for anything built of metal that is exposed to the elements
and for a ship it can be fatal. Corrosion of metallic structure is likely
to be more extensive and work more rapidly than on other structures simply
because the ship is in continual contact with water, usually seawater. It
can also be accelerated by the effects of some cargoes, especially those carried
in bulk. The interior of cargo holds can be affected by humidity resulting
from the moisture contained in some bulk cargoes. Sulphuric acid can be formed
from sulphur residues (which can come from coal) combining with water resulting
There are various
ways of preventing corrosion - or at least of preventing it from becoming
a problem. Tanks can be painted with special coatings and can be carefully
washed out. Above all, the condition of the hull and other structures can
be continually checked for signs of corrosion or fatigue. This, however,
is much easier said than done. There is, in the first place, a great deal
of steelwork to be checked. A bulk carrier of 254,000 deadweight tons (representing
roughly the amount of cargo it can carry) might be 320 metres long, 54 metres
in breadth and 26 metres deep. The total hull area to be examined could thus
be in excess of 54,000 square metres and that does not include the interior
bulkheads, hopper tanks, brackets and other features. All of this has to
be surveyed and inspected - a daunting task that requires the use of special
staging, artificial light and a considerable amount of stamina on the part
of the surveyor or surveyors involved.
seems to have played a significant part in many of the bulk carrier accidents
of recent years - especially the most serious losses. An Intercargo analysis
of 15 total losses in 1994 showed that 40% were caused by plate failure and
subsequent ingress of water. A further 6.7% of losses were never explained
because the ships involved disappeared. More than 70% of these losses occurred
in heavy weather.
found that of 29 fatal accidents involving bulk carriers between 1990 and
1994, 55% were due to plate failure. In terms of lives lost 81% were associated
with sinkings and disappearances. In 12 cases adverse weather was a factor
and in 67% of the cases, iron ore was the cargo. Not surprisingly, the Intercargo
report states: “The inescapable conclusion from this analysis is the fairly
obvious one that it is plate failure, taking water and disappearance which
cause the majority of fatal accidents. Thus, although during the whole period
losses related to human factors account for 33% of all bulker and OBO losses,
such accidents comprise only 10% of fatal accidents and involve only 7% of
the total fatalities...it is structural failure, aggravated by bad weather
and the carriage of iron ore which causes the majority of the really serious
accidents involving loss of life.”
references to iron ore are significant because once laden bulk cargo carriers
get into trouble, the consequences can be very sudden. The ships are designed
to withstand bad conditions, but not to operate with several holds flooded
and the combination of iron ore and a sudden inrush of seawater can result
in more weight than the structure can stand. Other investigations came to
similar conclusions. The American Bureau of Shipping said in 1991: “The recent
spate of casualties on conventional bulk carriers appears to be directly traceable
to failure of the cargo hold structure...”
of Shipping concluded that the prime cause of most casualties is the inability
of the side structure to withstand the combination of local corrosion, fatigue
cracking and operational damage. The evidence of the disastrous consequences
of uncontrolled corrosion is overwhelming - but preventing it is not so easy
as it sounds, if only because of the size of the ships themselves and the
difficulties involved in assessing corrosion and plate thickness.
A report by
Lloyd’s Register in the autumn of 1991 stated that the owner of one ten-year
old Capesize bulk carrier estimated that the wastage rate of hold frames due
to corrosion amounted to 0.5mm per year - and 1mm in some places. Some frames
had suffered metal wastage of 20%. During one voyage from South America to
Japan a bracket which was in good condition when the ship left became completely
detached, leaving a 1.4mm crack. It was not detected because “the rust scale
adhering to the surface of the hold structures presented a smooth and regular
surface to the eye on visual inspection, making it difficult to detect any
cracking.” Since the side plates of a bulk carrier may only be 20mm to 29mm
thick the loss of a few millimetres can be disastrous.
Like many of
the other studies carried out, the Lloyd’s Register report said that structural
failures were due to a combination of factors. Corrosion was important -
but so was physical damage suffered during operations. Bulk carriers are
designed to withstand heavy seas. The massive structures of the largest ships
will bend with the action of the sea. When the centre of the hull is higher
than the bow and stern the action is known as “hogging”: the reverse is called
“sagging”. But the design assumes that the hull is sound. Corrosion or other
damage can lead to weaknesses developing that invalidate the calculations
of the naval architect and imperil the whole ship. Loading patterns can make
the effect worse. Dense cargoes such as iron ore are often carried in alternate
holds in order to raise the ship’s centre of gravity and moderate its roll
motions. But this places greater stress on frames and girders and, because
holds carrying iron ore are not completely filled, there can be greater side
frame deflection. The overall result is increased stress on inner hull components,
according to Lloyd’s Register. This might be perfectly acceptable in a new
ship - but not in a ship that has suffered from 20 years of hard service and
originally chosen for operational reasons may also have safety implications.
Many bulk carriers are fitted with very large hatch openings to facilitate
cargo loading and unloading. Yet these openings may represent points of weakness
in the hull since they reduce the torsional resistance of the hull.
methods have also been criticized. These have changed considerably in recent
years, with the emphasis being to load and unload the ship as quickly as possible
so that the berth can be cleared for the next ship. In some loading terminals
iron ore can be loaded at up to 16,000 tons an hour by means of conveyor belts
often several kilometres long. Stopping the loading process for some reason
cannot be done simply by pressing a button - it has to be very carefully planned
and can take several minutes to carry out. In these circumstances it is not
surprising that bulk carriers can sometimes be overloaded. The International
Association of Classification Societies (IACS) says that there is no evidence
that high loading rates causes physical damage to the interior of cargo holds
(assuming that they are in good condition to begin with) but “high cargo loading
rates under an uncontrolled process could result in inadvertent overloading
which could cause local or global damage.” Dramatic proof of what can happen
if something goes wrong during loading came in 1994 when a bulk carrier broke
in half while being loaded at a port in South America.
From a distance, it is possible to
mistake a bulk carrier for an oil tanker, but there is one crucial difference:
although both ship types are divided into a series of huge cargo holds, bulk
carriers have hatch covers which have to be opened when cargo is loaded and
unloaded. These extend almost the width of the ship and can represent a point
of weakness in the hull structure, especially in severe weather, when the
hull is subject to considerable wave action. This photograph shows just how
huge the hold of a bulk carrier – and its hatch cover – can be. The International
Maritime Organization is now intensively studying hatch cover strength.
A study carried
out by IACS members showed that a 5% overload placed in various holds could
increase the stillwater bending moment by up to 15% and the sheer force by
up to 5% while a 10% overload could increase the still water bending moment
by up to 40% and the sheer force by up to 20%. A 10% overload, according to
IACS (in reply to questions submitted by the Nautical Institute) could be
caused by a five to eight minute delay in stopping a conveyor belt with a
capacity of 16,000 tons an hour. At the other end of the voyage, other problems
can be waiting. Bulk cargoes are removed from the hold by means of huge grabs,
which can weigh up to 36 tons. The last tons of cargo, which may be caught
up in frame webs and other parts of the hold, are often removed by bulldozers
and hydraulic hammers fitted to the extending arms of tractors. There is
always a danger that the hull - especially if it is suffering from corrosion
or fatigue - may inadvertently be damaged in the process. Part of the problem
is that modern loading and unloading techniques were developed long after
the ships they are intended to load were built. The need for speed may have
compounded the problem in some cases. An article in the August 1995 edition
of the BIMCO Bulletin, the magazine of the Baltic and International Maritime
Council, observed that, “there has been a growing body of evidence that terminals,
which were often owned by the cargo owners or charterers of the ship, were
putting pressure upon the ships to amend their loading plans or to load cargo
to suit them, with little consideration about the overall safety of the ship.”
This graphic, based on the Intercargo
study, shows how safety of bulk cargo carriers has improved since 1990. Nevertheless,
the number of losses has fluctuated and is still worryingly high, especially
when the increasing number of ageing ships is taken into account.
A Question of Attitude
The idea that
commercial considerations could threaten safety has been noted by other sectors
of the shipping industry. A study by Lloyd’s Register discovered that “operational
damage was accepted as the norm by the operators of bulkers and OBOs; second,
there was little awareness as to the significance of this damage and its likely
consequences on the capability of the ship under adverse operating conditions.”
This might be put down to simple thoughtlessness, but that excuse cannot be
made for shipowners who purposely move their vessels from one trade to another
- to escape increasingly vigilant port State control inspections. That is
what happened when Australia, alarmed by a number of accidents involving elderly
bulk carriers visiting its ports, tightened its port control procedures.
was a rapid switch of tonnage from the Pacific to the Atlantic where inspections
were apparently not as rigorous. According to Lloyd’s List “in the first
nine months of 1989 there were nine voyages with Capesize vessels aged 20
years or more in the transAtlantic trades. In the corresponding 1993 period
that figure had increased to 152.” It is difficult to avoid the conclusion
that the owners of at least some of the ships concerned moved them because
they knew that the ships were in such bad condition that they would not be
allowed to operate in Australia - or even leave port - without being repaired.
The owners were presumably quite content to allow the crews to risk their
lives on ships which they knew were unseaworthy.
It is not surprising
in the circumstances that, when Lloyd’s Register of Shipping began to investigate
bulk carrier losses in 1991 it found that “one of the biggest problems facing
LR ...is the general attitude of the industry. It is thought by some in the
industry that cracking in these structures is inevitable due to the harsh
nature of the cargoes and the rigorous operational procedures throughout their
High tensile steel
Most of the
concern about the condition of bulk carriers has focused on old ships, especially
those aged more than 20 years. But young ships are not immune to neglect
and corrosion and there is also evidence that changes in the steel used on
some relatively young bulk carriers could present even more serious problems
than those experienced by earlier designs.
of ships operating today are built of mild steel. But since the early-1980s
increasing use has been made of high-tensile (HT) steel, especially in the
construction of bulk carriers. HT steel has been used in shipbuilding since
1907 but its recent popularity is due to the fact that plates can be thinner
without losing any strength. Whereas a normal side plate will be 24-29mm
thick, this can be reduced to 20mm by using HT steel. The weight saving -
which might amount to several thousand tons - cuts building costs and also
enables the ship to carry more cargo. However, for these savings a price
has to be paid. One is the simple fact that HT steel corrodes just as quickly
as mild steel. Since HT plates are thinner than those of mild steel, corrosion
is likely to reach the danger point more quickly. A second problem is that
HTS-built ships are more prone to structural problems caused by the way in
which load is transmitted through the ships’ structural components and the
inter-dependency of the structural response.
that the most common example where failure had occurred on HTS-built bulk
carriers was at side longitudinal connections to web frames. According to
Lloyd’s September 1995 Shipping Economist, HTS-built ships are also prone
to a phenomenon known as “springing”: because the ships are flexible and tend
to vibrate with short sea waves. The article stated that “classification
society rules have always been based on empirical evidence from previous generations
of ships, but the increased use of HTS changed the characteristics of vessels
and therefore represented a step into the unknown.”
It is clear
from the above that HTS ships need at least as much care and maintenance as
those built of mild steel, especially as they too are frequently subject to
greater stresses in cargo loading and unloading than was originally envisaged.
Many shipping experts believe that whereas mild steel bulk carriers usually
begin to experience major problems at the age of 20, those built of HTS will
do so much earlier. Since most of those built in the early 1980s are already
in their late-teens, the danger is that there could be another rise in bulk
carrier casualties, unless action is taken to prevent it.
increase in bulk carrier losses in 1990 and 1991 caused considerable alarm
in the shipping industry. In response, the IMO Assembly adopted Resolution
A.713 (17) (“Safety of Ships Carrying Dry Bulk Cargoes”) which contains interim
measures designed to improve the safety of ships carrying solid bulk cargoes.
The preamble expressed concern at the continuing loss of bulk cargo carriers
and the heavy loss of life incurred. The resolution noted that the nature
of cargo and ballast operations could subject bulk carriers to severe patterns
of bending and sheer forces and also to significant wear. It referred to
the dangers posed by some bulk cargoes through their high density and tendency
of not overstressing the ship’s structure during cargo operations was emphasized
and governments were advised to pay particular attention to the structural
integrity and seaworthiness of ships when port State control procedures are
carried out under SOLAS.
were encouraged to fit vessels with equipment to monitor the stresses on the
ship’s structure during the voyage and during cargo operations. They were
also encouraged to install equipment required by the Global Maritime Distress
and Safety System (GMDSS), which entered into force on 1 February 1992 but
which did not become mandatory for most existing ships until 1999.
of this resolution and action initiated by major classification societies
was immediately beneficial. The number of bulk carrier losses dropped to
just two within the next year. What is most significant about this improvement
is that the resolution did not introduce any new measures but simply stressed
the importance of implementing existing standards. From this it is possible
to conclude that at least some of the casualties that occurred in 1990 and
1991 were due not to defects in the regulations covering bulk carrier safety
but to the ineffective way in which they were implemented.
life on bulk carriers
based on the Intercargo study shows that 637 seafarers lost their lives in
bulk carrier accidents between 1990 and 1997. Of these 227 died when the ship
sank through taking on water or plate failure. A further 150 were lost as
a result of disappearances (usually associated with bad weather) while another
119 deaths were attributed to adverse weather.
implementation of regulations is a problem that concerns all forms of shipping
and is one that IMO has been treating with even greater urgency. Successful
implementation depends upon a number of factors, but to be really effective
it requires everybody involved doing their job efficiently and with the necessary
commitment and dedication.
water and plate failure
not by engine failure
fire and explosions
in implementation are:
Governments which have ratified conventions and thereby promised to
put them into force
have authority under conventions to check that foreign ships visiting
their ports comply with IMO requirements
own the ships and have the greatest responsibility - and opportunity
- for ensuring that they are maintained in good condition.
training and skill are vital to shipping safety and who stand to suffer
most if something goes wrong.
taken by IMO to improve implementation have been particularly important
a Sub-Committee on Flag State Implementation, which spotlights some
of the problems Governments have in enforcing IMO conventions and provides
guidance in overcoming them
the establishment of regional port State control systems. Regional systems
are especially useful in improving port State control because ships
normally visit more than one country in a particular region. Regional
co-operation in inspecting and surveying ships ensures that few sub-standard
ships avoid the net - and that ships in good condition are not inspected
unnecessarily adopted guidelines on management for the safe operation
of ships and for pollution prevention
were replaced by an International Safety Management Code (ISM Code)
which became mandatory in 1998 through a new chapter IX of SOLAS
revision of the International Convention on Standards of Training, Certification
and Watchkeeping for Seafarers (STCW) in 1995 and became effective in
February 1997. The Convention introduce strict new controls which will
enable IMO to validate the training and certification procedures of
Parties to the Convention.
on Ship Design and Equipment (DE) began work on measures to do with constructional
safety, especially the hull integrity of large ships and installation of a
monitoring system that would provide information to the master of the ship
while the ship was under way and during loading and unloading operations.
Such a system might prevent the accident from happening in the first place.
The recommendation was subsequently issued as MSC/Circ.646. The Circular
contains guidance on the fitting of hull stress monitoring systems (HTMS)
and recommends that they be fitted to bulk carriers of 20,000 dwt and above.
Governments were asked to provide IMO with information on experience gained.
also considered ways of combating corrosion of seawater ballast tanks, a problem
shared by both bulk carriers and oil tankers. It included the regulation
14-1 in Chapter II-1 of SOLAS, which requires all dedicated seawater ballast
tanks to be provided with an efficient corrosion prevention system, and the
relevant guidelines. These guidelines were adopted by the IMO Assembly in
1995 by resolution A.798 (19). The regulation itself was included in amendments
to SOLAS adopted by the 66th session of the MSC in 1995 which entered into
force in 1998.
A.713 (17) emphasized the importance of regular inspections of bulk carriers,
especially of older ships, and in 1993 guidelines on an enhanced programme
of inspections during surveys of bulk carriers and oil tankers were adopted
by the 18th Assembly by resolution A.744 (18). It was originally intended
that the guidelines would apply to tankers but because of concern about the
loss of bulk carriers they were extended to them as well. The guidelines
were regarded as so important to safety that amendments to SOLAS to make them
mandatory were adopted in May 1994 and entered into force on 1 January 1996.
apply to existing tankers and bulk carriers of five years of age and over
which means that the vast majority of the world tankers and bulk carriers
are affected. The enhanced surveys must be carried out during the periodical,
intermediate and annual surveys prescribed by the SOLAS Convention. The enhanced
survey programme is mandatory for oil tankers under Regulation 13G of Annex
I to the International Convention for the Prevention of Pollution from Ships,
1973, as modified by the Protocol of 1978 relating thereto (MARPOL 73/78).
The guidelines pay special attention to corrosion. Coatings and tank corrosion
prevention systems must be thoroughly checked and measurements must also be
carried out to check the thickness of plates. These measurements become more
extensive as the ship ages. The guidelines go into considerable detail to
explain the extra checks that should be carried out during enhanced surveys.
One section deals with preparations for surveys and another with the documentation
which should be kept on board each ship and be readily available to surveyors.
This should record full reports of all surveys carried out on the ship.
the guidelines go into still more detail and are intended to assist implementation.
They specify the structural members that should be examined, for example,
in areas of extensive corrosion; outline procedures for certification of companies
engaged in thickness measurement of hull structures; recommend procedures
for thickness measurements and close-up surveys; and give guidance on preparing
the documentation required.
planning the enhanced programme of inspections was adopted by the MSC in May
1994 and issued by means of MSC/Circ.655.
on Dangerous Goods, Solid Cargoes and Containers (DSC) considered ways of
improving the safety of loading and unloading operations. One aim was to
amend Chapter VI of SOLAS so that ship masters would be provided with sufficient
information on cargoes to be able to assess stress limitations. A questionnaire,
issued as MSC/Circ.611 deals with the loading and unloading of bulk cargoes
based on a model plan prepared by the Nautical Institute and the International
Federation of Shipmasters’ Associations (IFSMA). Other organizations were
also working to improve bulk carrier safety, including the leading classification
societies, most of whom are members of the International Association of Classification
circulars were issued in December 1994. MSC/Circ. 665 is concerned with the
duties of Chief Mate and Officer of the Watch at bulk cargo loading and discharge
ports. It contains checklists that are designed to ensure that loading and
unloading is carried out safely. The circular was superseded in June 1995
by MSC/Circ. 690, which contains an improved model ship/shore safety checklist.
MSC/Circ. 666 contains a cargo operation form, which is intended to ensure
proper planning and calculation prior to the commencement of cargo operations.
MSC/Circ. 667 contains general advice on bulk carrier safety. It stresses,
for example, the importance of reducing corrosion within holds and ballast
tanks by maintaining paint coatings and gives guidance on where corrosion
is most likely to occur.
here for Details on MSC Circulars 667
A new chapter
XII to SOLAS - Additional Safety Measures for Bulk Carriers, adopted
by the November 1997 SOLAS Conference entered into force on 1 July 1999.
It covers survivability and structural requirements to prevent bulk carriers
from sinking if water enters the ship for any reason. Existing ships which
do not comply with the appropriate requirements will have to be reinforced
- or they may have to limit either the loading pattern of the cargoes they
carry or move to carrying lighter cargoes, such as grain or timber.
stipulate that all new bulk carriers 150 metres or more in length (built after
1 July 1999) carrying cargoes with a density of 1,000 kg/m3 and
above should have sufficient strength to withstand flooding of any one cargo
hold, taking into account dynamic effects resulting from presence of water
in the hold and taking into account recommendations adopted by IMO.
ships (built before 1 July 1999) carrying bulk cargoes with a density of 1,780
kg/m3 and above, the transverse watertight bulkhead between the
two foremost cargo holds and the double bottom of the foremost cargo hold
should have sufficient strength to withstand flooding and the related dynamic
effects in the foremost cargo hold.
a density of 1,780 kg/m3 and above include iron ore, pig iron,
steel, bauxite and cement. Less dense cargoes, but with a density of more
than 1,000 kg/m3, include grains such as wheat and rice, and timber.
allows surveyors to take into account restrictions on the cargo carried when
considering the need for, and the extent of, strengthening of the transverse
watertight bulkhead or double bottom. When restrictions on cargoes are imposed,
the bulk carrier should be permanently marked with a solid triangle on its
side shell. The date of application of Chapter XII to existing bulk carriers
depends on their age. Bulk carriers which are 20 years old and over on 1 July
1999 have to comply by the date of the first intermediate or periodical survey
after that date, whichever is sooner. Bulk carriers aged 15-20 years must
comply by the first periodical survey after 1 July 1999, but not later than
1 July 2002. Bulk carriers less than 15 years old must comply by the date
of the first periodical survey after the ship reaches 15 years of age, but
not later than the date on which the ship reaches 17 years of age.
publication of the report on the 1980 sinking of the bulk carrier Derbyshire
in the South China Sea with the loss of all on board, a formal safety assessment
(FSA) study of bulk carriers by the United Kingdom to aid future IMO decision-making
on bulk carrier safety.
FSA is a process
for assessing the risks associated with any sphere of activity, and for evaluating
the costs and benefits of different options for reducing those risks. It
therefore enables, in its potential application to the rule making process,
an objective assessment to be made of the need for, and content of, safety
regulations. The FSA consists of five steps: identification of hazards (a
list of all relevant accident scenarios with potential causes and outcomes);
assessment of risks (evaluation of risk factors); risk control options (devising
regulatory measures to control and reduce the identified risks); cost benefit
assessment (determining cost effectiveness of each risk control option); and
recommendations for decision-making (information about the hazards, their
associated risks and the cost effectiveness of alternative risk control options
The entry into
force on 1 July 1999 of the new Chapter XII to SOLAS on Additional Safety
Measures for Bulk Carriers was a significant step in improving bulk carrier
safety and was the culmination of a lengthy process involving Governments,
shipowners and classification societies in looking at all aspects of bulk
carriers, from operational issues to their design and structure.
FSA study on bulk carriers will go some way to helping IMO in the process
of deciding which regulations – or amendments - will be appropriate. Indeed,
this is part of IMO policy to move to a more pro-active approach. Instead
of solely responding to disasters, a preventive and prospective approach is
necessary by using statistical analysis to identify potential problems and
ensuring that new measures are safe. The results of the FSA study which are
due in 2001 will help analyse the likelihood of occurrence of disasters such
as the Derbyshire, and the measures needed to prevent it. The work
on bulk carrier safety is also being carried out against the broader context
of IMO’s moves to improve implementation of existing IMO instruments and in
reducing human error – still seen as the cause of most accidents at sea.
that represents many of the world’s dry bulk carrier operators at international
meetings is Intercargo. In May 2000 Intercargo published its latest Bulk Carrier
Casualty Report giving details of losses in 1999 and ten years of data for
the period 1990-1999. This showed that “the trend in the number of bulk carriers
lost can be said to be declining; however, the statistical significance of
this decline remains marginal.” The greatest number of vessels lost in one
year was 22 (1991) and the least was 8 (1995).
shows that older bulk carriers are much more at risk than those under 15 years
of age. The average of bulk carriers lost at sea during the decade was 19.5
years. Although weather is often associated with losses at sea the Intercargo
report says that “a well-found or well-navigated ship should be able to survive
all but the most severe weather conditions. In nearly all cases weather is
unlikely to have been the primary cause of loss.” This is generally related
to the age and condition of the ship.
says that the primary cause of bulk carrier losses and loss of life in bulk
carrier casualties are related to structural failure. Although the loss record
of bulk carriers is no worse than that for other sectors of shipping, the
loss of life associated with rapid sinking “is too high and is preventable.”
says that bulk carrier casualties “have their genesis in the failings of shore-based
age of bulk carriers lost 1990-1997(Left)
in bulk carrier accidents 1990-1997(Right)
shows the strong link between structural failure and loss of life. Because
of the density of the cargo carried, bulk carriers are particularly vulnerable
is the ship’s structure is seriously damaged and water enters the cargo holds.
For further information about bulk carriers, please go to these links:
of IMO has prepared an extensive bibliography of Internet links and other
information about bulk carriers, which can be found at:
Association of Classification Societies (IACS) has published Bulk Carriers:
Guidance and Information on Bulk Carrier Loading and Discharging to Reduce
the Likelihood of Over-stressing the Hull Structure. It is available for downloading
on the IACS web site at http://www.iacs.org.uk/publications/bulkguid.pdf.
 Add link to the paper entitled International Maritime