Neptune Atlas logo Neptune Atlas

Lashing

Cargo securing and lashing

·

Cargo does not break loose because the ship leans over a long way; it breaks loose because the ship leans over quickly. The force on a lashing comes from acceleration, and acceleration grows as each roll gets shorter. A ship with a large metacentric height, which measures how strongly a ship pushes itself back upright, rolls quickly. Its stability figures look the best on paper, but it is the ship that is hardest on its cargo.

The stiff ship problem

A ship with a high metacentric height is called stiff: it pushes itself back upright hard and rolls in short, sharp movements. A tender ship rolls further and more slowly. Most people assume the stiff ship is safer, and for the survival of the ship it usually is, but for the cargo it is the opposite. The sideways force on a piece of cargo depends on how fast the ship changes direction. It does not depend on how far the ship rolls.

This is a real problem in practice, not just an interesting fact. The loading plan that gives the most stability puts heavy weights low and in the centre. That plan also gives the roughest motion. On a heavy lift voyage, the answer is often to accept a lower metacentric height on purpose. A general cargo plan is the kind of plan least likely to be checked for this.

The Cargo Securing Manual

Every ship that carries cargo other than solid or liquid bulk must carry a Cargo Securing Manual. The ship's flag State must approve it. SOLAS chapters VI and VII require it. Its content follows the IMO guidelines in MSC.1/Circ.1353. The latest revision is Rev.2, from December 2020.

The manual is written for one ship. It lists the fixed securing points and their strength, the portable securing equipment on board and its maximum securing load, the approved ways to stow and secure the cargoes the ship normally carries, and how the gear is inspected and maintained. It is not general advice but the ship's own document, and Port State Control inspectors look at it.

Its limit in practice is what it leaves out. The manual plans for the usual cargoes. Anything else must be assessed separately, and that includes most project cargo.

Annex 13, and the arithmetic that decides

Annex 13 of the IMO Code of Safe Practice for Cargo Stowage and Securing is the method for non-standard cargo. It compares the forces from the ship's movement with the friction and the strength of the securing devices. It checks three different ways the cargo can fail.

Failure modeWhat is being resisted
Transverse slidingThe piece slides sideways across the deck. Friction does most of the work, and the lashings cover the rest
Transverse tippingThe piece turns over about its outer edge. A tall, narrow piece tips over long before it slides
Longitudinal slidingMovement forward and back, caused by the ship pitching and rising and falling. Usually the easiest of the three to resist, but you still cannot ignore it

The strength side of the calculation uses the maximum securing load of each device. A safety factor is applied, because lashings never share the load evenly. There is also a simpler rule-of-thumb method. It compares the total strength of the securing devices with the weight of the cargo. It is useful for a first look. It does not replace the full calculation for anything unusual.

Two basic points apply to all of this, and they are easy to forget. First, friction gives a large part of the resistance. So the material between the cargo and the deck matters. Dunnage (timber packing), rubber mats or bare steel give clearly different results. Second, a lashing is only as strong as the point it is fixed to. The securing point on the deck is often the weakest part, not the chain.

Containers are the other half of the subject

Container securing has its own rules. It uses lashing bridges, twistlocks (locks that join containers at the corners) and an approved lashing plan. The ship's software makes a new plan for each loading condition. When cargo fails here, the cause is usually not the lashing. It is what happened inside the box. The cargo was not fixed to the walls of the container. Or the declared weight was not the real weight, so the stack was loaded differently from the plan.

A related code covers this: the IMO, ILO and UNECE Code of Practice for Packing of Cargo Transport Units, called the CTU Code, published in 2014. It covers packing and securing inside the container. It is not mandatory. Yet most damage to container cargo starts in the area it covers.

The size of the problem is now measured in public. The World Shipping Council publishes a yearly estimate of containers lost at sea. From 1 January 2026, reporting is no longer voluntary. SOLAS regulations V/31 and V/32 were changed. If a ship loses containers, its master must report this without delay to nearby ships, to the nearest coastal State and to the flag State. Containers seen drifting at sea must also be reported, even by ships that did not lose them.

Who pays for the work

Lashing needs labour and materials, and who pays for both is negotiated rather than assumed. The handling terms in the recap (the written summary of the deal) settle it, and every letter in the abbreviations matters.

None of these terms moves responsibility for the seaworthiness of the stowage. The master keeps the right and the duty to refuse any stowage or securing that the master thinks is unsafe, whoever is paying for it. A charterer who pays for the lashing does not make the decision because of that.

The failures worth recognising

Almost every securing failure is one of four things: lashings tightened at the berth and never checked again, so that they go slack once the cargo settles; a securing point weaker than the lashing fixed to it; friction counted on a steel deck that was in fact wet or oily; and a stowage that suited the weather in the plan but then met worse weather at sea.

None of these is unusual, and all of them can be avoided at the planning stage. That is the reason to treat securing as part of the fixture. It should not be something the ship deals with after the cargo is on board.

References

Breakbulk and project cargoCargo that is counted in pieces, not tonnes, where the largest piece decides which ship can carry it. Dangerous goods and the IMDG CodeFour pieces of information turn a hazardous cargo into one that can be shipped. An enquiry without them is not yet an enquiry. Stowage factor and broken stowageTwo numbers that both turn space into tonnes. Only one of them is printed in the cargo book. Chartering terms and abbreviations, A to Z177 chartering terms and short forms from a circular, an enquiry and a recap, each expanded and defined in a sentence or two.

Neptune Atlas

Neptune Atlas records the handling terms agreed in a fixture. So who pays for lashing and securing is part of the recap. Each side does not have to remember it differently when the invoice arrives. Every paid plan starts with 7 free days. A card is needed to start them, and cancelling before they end costs nothing.

Try 7 days free Ship chartering software for brokers What each plan includes