A cargo that looked dry and granular at the loading berth can behave as a liquid a few days into the voyage. When it does, the ship can capsize before anyone reaches a lifeboat, and the loading ports where it happens most are on Malaysia’s doorstep.
Why the Ship Goes Over So Fast
Unprocessed mineral ores and refined concentrates arrive aboard looking like any other dry bulk: granular, stable, unremarkable. What is not visible is the water held between the particles. Under the compaction and vibration of a voyage, that pore water pressure builds until the material loses its shear strength and begins to behave as a fluid.
The consequence is a stability problem rather than a cargo problem. A solid cargo stays where it is stowed. A liquefied one flows to one side as the ship rolls, and does not flow back in time to correct the next roll. Each cycle moves more mass off the centreline. The vessel develops a progressive list, loses righting ability, and capsizes. Liquefaction of fine-particled cargoes has been associated with the loss of life in numerous recent casualties, and the speed is what makes it lethal: by the time the list is obvious, the situation is often already unrecoverable.
A shifting solid cargo is a stability problem you can fight. A liquefied one moves faster than the ship can recover, and it keeps moving with every roll.
A related phenomenon, dynamic separation, affects certain cargoes including bauxite, where moisture migrates upward to form a slurry layer above the settled solids. The effect on stability is comparable and the precautions overlap.
What the Code Requires
The International Maritime Solid Bulk Cargoes Code is mandatory under SOLAS, and it sorts cargoes into three groups. Group A may liquefy if shipped at a moisture content above its transportable moisture limit. Group B possesses a chemical hazard. Group C is neither.
Group A now includes nickel ore, iron ore fines and bauxite fines. Those schedules exist because ships were lost: nickel ore was once unlisted, and iron ore and bauxite were once carried as Group C. The list is updated as experience accumulates, and the latest amendments to the Code took effect on 1 January 2025 after a year of voluntary application.
Accurate cargo information, provided to the master sufficiently in advance of loading to allow precautions to be taken.
A signed certificate of the transportable moisture limit, established by an approved test method.
A signed certificate or declaration of moisture content, representative of the cargo as it will be loaded and issued no more than seven days before loading.
Sampling and testing to approved procedures. The Code requires procedures developed for the cargo’s properties and approved by the competent authority of the country of origin or the port of loading, which means they differ from port to port.
The arithmetic that matters: where TML is determined by flow table or penetration test it is set at 90% of the flow moisture point; under the Proctor/Fagerberg method it is 70% or 80% depending on the variant. Moisture content must sit below whichever figure applies.
Why the Certificate Cannot Be Taken on Trust
The documents above are the shipper’s duty, and on a well-run trade they are reliable. The difficulty is structural rather than a matter of assuming bad faith.
Sampling procedures are approved locally, so what counts as representative sampling varies between ports. Certification may reflect a stockpile tested before rain fell on it, or a section of a stockpile that is not representative of what reaches the hold. And a certificate seven days old describes the cargo as it was, not necessarily as it is at the moment of loading, which matters in tropical loading ports during a wet season.
There is also a commercial dimension the industry has documented openly. Shipowners and their representatives have in many cases been denied the opportunity to sample cargoes for moisture content before loading, sometimes under considerable pressure. That experience is precisely why the International Group of P&I Clubs approached BIMCO to develop a standard charter party clause for solid bulk cargoes that can liquefy, published in 2012, which requires charterers to provide the shipper’s written evidence on moisture content in advance and establishes the owner’s right to take and test samples.
A moisture certificate describes a sample taken somewhere, by someone, at some point in the last week. None of those three is guaranteed to match what is going into your hold.
The Can Test, and Its One Limitation
The Code provides a simple shipboard check. A cylindrical can is half filled with the material and struck sharply against a hard surface repeatedly. If free moisture or a fluid condition appears, the cargo is too wet and the material must not be loaded without further laboratory testing.
The critical point, and the one that gets missed, sits in section 8.4 of the Code: if samples remain dry following a can test, the moisture content of the material may still exceed the transportable moisture limit. The can test can therefore condemn a cargo but can never clear one.
That asymmetry should govern how it is used. A positive result is decisive and stops loading. A negative result is reassurance only, and does not displace the need for proper certification and, where doubt persists, independent laboratory testing. Treating a clean can test as permission to load is the error the Code specifically warns against.
The Master’s Position
A master confronted with a cargo they believe unsafe is not without authority, and the position is stronger than many realise.
The charter party clause matters commercially because it settles who pays. Where the clause is incorporated, charterers are responsible for the costs and the time involved in making the cargo safe or replacing it. Without it, a master refusing cargo faces a dispute about delay on top of a dispute about safety, which is why the clause belongs in fixtures for these trades rather than being negotiated after a problem appears.
Documentation of the decision is what protects the position afterwards. Can test results with times and locations, photographs of the stockpile and the loading operation, weather records, and the correspondence with charterers and shippers. A master who refused cargo and can evidence why is in a very different position from one who refused on judgement alone.
Why This Sits on the Regional Doorstep
The trades that generate these losses run close to home. Nickel ore moves in volume from Indonesian and Philippine ports, and bauxite from several regional sources, much of it loaded at facilities where cargo is stockpiled in the open in a climate that delivers heavy and unpredictable rainfall.
That combination, fine-particled ore, open storage, tropical rain and loading by barge and grab, is the one the Code was written for. It also means the practical burden falls disproportionately on masters and operators trading in this region, who encounter Group A cargoes far more often than the global average and who are dealing with loading facilities of widely varying standards.
None of this makes the trade unworkable. It makes it a trade where the documents are checked properly, the can test is run and correctly interpreted, the stockpile is looked at rather than assumed, and the authority to stop is understood in advance by everyone who might need to use it. The ships that have been lost were not lost because the rules were unclear. They were lost because someone accepted a certificate that turned out not to describe what was in the hold.
Frequently Asked Questions
Why does liquefaction capsize ships so quickly?
Because a liquefied cargo flows to one side as the vessel rolls and does not return in time to correct the next roll, so each cycle moves more mass off the centreline. The ship develops a progressive list and loses righting ability. Unlike a shifting solid cargo, which can sometimes be managed, liquefaction moves faster than the vessel can recover, and by the time the list is obvious the situation may already be unrecoverable.
What must a shipper provide before loading a Group A cargo?
Accurate cargo information sufficiently in advance of loading, a signed certificate of the transportable moisture limit, and a signed certificate or declaration of the moisture content issued no more than seven days before loading. Sampling and testing must follow procedures approved by the competent authority of the country of origin or port of loading, which means the procedures differ between ports.
Does a negative can test mean the cargo is safe?
No, and this is the most important limitation to understand. Section 8.4 of the IMSBC Code states that if samples remain dry following a can test, the moisture content may still exceed the transportable moisture limit. The test can condemn a cargo but cannot clear one, so a negative result does not displace the need for proper certification and, where doubt remains, independent laboratory testing.
Can a master refuse to load a cargo they believe is unsafe?
Yes. Where the BIMCO Solid Bulk Cargoes that Can Liquefy Clause is incorporated into the charter party, the master may require cargo to be made safe, offloaded and replaced, or refuse to sail if the cargo is considered hazardous to vessel and crew, with charterers responsible for the costs. The clause was developed with the International Group of P&I Clubs in response to owners being denied the chance to sample cargo before loading.
Sources: IMO International Maritime Solid Bulk Cargoes (IMSBC) Code, mandatory under SOLAS Chapter VI, including the Group A, B and C classification, section 4 shipper information and certification duties, section 8 test procedures and the complementary can test in section 8.4, and the individual schedules for nickel ore, iron ore fines and bauxite fines; latest amendments in force 1 January 2025 · BIMCO, Solid Bulk Cargoes that Can Liquefy Clause for Charter Parties 2012, developed with the International Group of P&I Clubs · IMO SOLAS Chapter VI, Carriage of cargoes and oil fuels
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