Neptune Atlas

Lashing

Cargo securing and lashing

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Cargo does not break loose because the ship heels a long way. It breaks loose because she heels quickly. What acts on a lashing is an acceleration, and acceleration rises as the roll period shortens, which means a ship with a large metacentric height, the one whose stability figures look best on paper, is the one that treats her cargo worst.

The stiff ship problem

A ship with a high metacentric height is stiff: she rights herself hard and rolls through a short, snappy period. A tender ship rolls further and more slowly. Intuition says the stiff ship is safer, and for survivability it usually is. For the cargo it is the opposite, because the transverse force on a piece of cargo comes from how fast the ship reverses direction, not from how far she goes.

This is a real operational conflict rather than a curiosity. The loading plan that maximises stability, heavy weights low and centred, produces the harshest motion. On a heavy lift voyage the answer is often to accept a lower metacentric height on purpose, which is exactly the decision a general cargo plan is least likely to be checked for.

The Cargo Securing Manual

Every ship engaged in the carriage of cargoes other than solid and liquid bulk must carry a Cargo Securing Manual approved by her flag State. It is required by SOLAS chapters VI and VII, and its content follows the IMO guidelines in MSC.1/Circ.1353, revised most recently as Rev.2 in December 2020.

The manual is specific to the ship. It lists the fixed securing points and their strength, the portable securing equipment carried and its maximum securing load, the approved stowage and securing arrangements for the cargoes she normally carries, and the inspection and maintenance regime for the gear. It is not general advice, it is the ship’s own document, and Port State Control looks at it.

Its practical limit is what it does not cover: the manual anticipates the usual cargoes, and anything outside them, which is most project cargo, has to be assessed separately.

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-standardised cargo. It works by balancing external forces from the ship’s motion against friction and the strength of the securing devices, and it checks three separate failure modes.

Failure modeWhat is being resisted
Transverse slidingThe piece slides sideways across the deck. Friction does most of the work and the lashings make up the difference
Transverse tippingThe piece rotates about its outboard edge. A tall narrow piece tips long before it slides
Longitudinal slidingFore and aft movement, driven by pitch and by heave. Usually the least demanding of the three, and not therefore ignorable

The strength side of the calculation uses the maximum securing load of each device, with a safety factor applied to allow for the fact that lashings never share load evenly. There is also a simplified rule-of-thumb method, in which the total strength of the securing devices is set against the weight of the cargo, useful for a first look and not a substitute for the calculation on anything unusual.

Two things sit underneath all of it and are easy to lose. Friction is a large part of the resistance, so the material between the cargo and the deck matters: dunnage, rubber mats or bare steel produce meaningfully different coefficients. And a lashing is only as strong as what it is made fast to, so the securing point on the deck, not the chain, is frequently the weakest element.

Containers are the other half of the subject

Container securing has its own regime, with lashing bridges, twistlocks and an approved lashing plan generated by the ship’s software for each loading condition. The cargo failure there is normally not the lashing but what happened inside the box: cargo not secured to the walls of the unit, or a declared weight that is not the real weight, so the stack is loaded differently from how it was planned.

The companion instrument is the IMO, ILO and UNECE Code of Practice for Packing of Cargo Transport Units, the CTU Code, published in 2014, which addresses packing and securing inside the unit. It is not mandatory, and its subject is where most container cargo damage originates.

The scale of the outcome is now measured openly. The World Shipping Council publishes an annual estimate of containers lost at sea, and from 1 January 2026 reporting stopped being voluntary: SOLAS regulations V/31 and V/32 were amended to require the master of any ship involved in the loss of containers to report it without delay to ships in the vicinity, to the nearest coastal State and to the flag State, and to require reporting of drifting containers that are merely observed.

Who pays for the work

Lashing is labour and materials, and both are negotiated rather than assumed. The handling terms in the recap are where it is settled, and the abbreviations are doing real work.

What none of these terms transfers is responsibility for the seaworthiness of the stowage. The master retains the right and the duty to refuse a stowage or a securing arrangement he considers unsafe, whoever is paying for it, and a charterer who has taken on the cost of lashing has not thereby taken over the decision.

The failures worth recognising

Almost every securing failure is one of four things. Lashings tensioned at the berth and never checked again, so that once the cargo settles they are slack and doing nothing. A securing point weaker than the lashing attached to it. Friction assumed on a steel deck that turned out to be wet or oily. And a stowage that was fine for the weather in the plan and met the weather that actually came.

None of them is exotic and all of them are avoidable at the planning stage, which is the argument for treating securing as part of the fixture rather than as something the ship sorts out after the cargo is aboard.

References

Breakbulk and project cargoThe cargo that is counted in pieces, not tonnes, and where the largest piece picks the vessel. Dangerous goods and the IMDG CodeFour pieces of information turn a hazardous cargo into a shippable one. An enquiry without them is not yet an enquiry. Stowage factor and broken stowageTwo numbers that both turn space into tonnes, and only one of them is printed in the cargo book. Chartering abbreviationsThe abbreviations on a circular, an enquiry and a recap, grouped by where you meet them, and what each one commits you to.

Neptune Atlas

Neptune Atlas records the handling terms a fixture was agreed on, so who pays for lashing and securing is part of the recap rather than something recalled differently by each side 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.

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