Heavy machinery can leave the factory in perfect condition and still arrive with damage caused by movement during transport. Vibration, braking, container movement, and changes in direction can all place force on the cargo, even when the journey looks smooth from the outside.
That is why heavy export cargo needs to be secured for the forces it may experience during the entire journey. In this guide, we explain the main forces that act on the load, four common securing methods, how to choose the right strapping material, and what to check before the container doors are closed.
What Secured Actually Means For Cargo?
Secured doesn’t mean tight. It means the cargo cannot move relative to the container floor when the container itself is thrown around.
That distinction matters more than anything else in this article. A load can be strapped down hard and still walk six inches across a container floor because nothing was resisting the sideways force. Tight is a feeling. Secured is a number.
The number comes from the IMO/ILO/UNECE CTU Code, which is the reference every serious surveyor works from. And the numbers are less forgiving than people assume.
Factors to Consider When Securing Cargo
The CTU Code expresses forces as a fraction of the cargo’s own weight. Here’s what you’re designing against:
- Road: 0.8 g forward, 0.5 g rearward, 0.5 g sideways
- Rail (combined transport): 0.5 g longitudinal and transverse under normal conditions, rising toward 1.0 g in abnormal ones
- Sea, Area A (significant wave height up to 8 m): 0.3–0.5 g longitudinal, 0.5 g transverse
- Sea, Area C (over 12 m): 0.4 g longitudinal, 0.8 g transverse
Read that last one again. A 4-tonne skid on a North Atlantic winter route is trying to move sideways with roughly 3.2 tonnes of force. Sideways — where your container has the least structure and your load usually has the least support.
Here’s the part that surprises people: the worst leg of most export journeys is the truck to the port, not the ocean. That 0.8 g braking figure is higher than anything a ship generates longitudinally. So cargo that “survived the sea fine” often took its damage in the first ninety minutes, on a highway, and just didn’t show it until unpacking.
Tips for Cargo Weight Distribution
You cannot secure a badly stowed container. Get this part right and everything after it gets easier.
- The centre of gravity stays low and central. Heavy items on the floor, ideally within the middle half of the container’s length.
- Respect the axle load, not just the payload. A 20 ft container legally holds ~28 tonnes but a road axle limit will stop you long before that.
- No more than 60% of the weight in either half. Rule of thumb, but it keeps you out of trouble with terminal weighing.
- Fill the voids. Every gap is a runway. Cargo doesn’t damage itself standing still — it damages itself accelerating into something.
- Never stack dense over fragile. Obvious, ignored constantly.
Four Methods for Securing Cargo
Everything in cargo securing is one of these four, or a combination.
1. Friction
The cheapest securing force you will ever get, and most exporters leave it on the table. A steel skid on a bare wooden container floor gives you maybe 0.2–0.3 friction. Slip a rubber anti-slip mat under it and you’re closer to 0.6. That mat costs a few hundred rupees and can cut your required lashing capacity by half.
2. Blocking and Bracing
Timber, dunnage bags, filler pallets — physical barriers that stop movement. Blocking works against the container walls and posts. It’s excellent longitudinally and weak transversely, because container side walls are thin corrugated steel, not structural bracing.
3. Lashing
Straps or chains running from the cargo to the container’s lashing points. Two families:
- Top-over (friction) lashing — the strap passes over the cargo and presses it into the floor, increasing friction. Needs high pre-tension to do anything.
- Direct lashing — the strap runs at an angle from a fixed point on the cargo to a lashing point, resisting force directly. Far more efficient. Keep the angle to the floor under 45°, or you’re just pushing down instead of holding back.
4. Bundling
Holding the load together so it behaves like one mass. This is where composite cord strapping does most of its work — coils, pipe bundles, timber packs, drum groups, brick and tile stacks.
How to Choose Securing Materials
This is the decision most guides skip, so let’s do it properly.
| Width | System strength | Typical use |
| 13 mm | 485–500 kg | Light palletised goods |
| 16 mm | 650–700 kg | Medium industrial bundling |
| 19 mm | 900–1,100 kg | Construction materials, machinery |
| 25 mm | 1,400–1,650 kg | Heavy equipment, steel coils |
| 32 mm | 2,000–2,300+ kg | Extreme heavy-duty, container lashing |
Three things to weigh:
- Elasticity. Steel band has almost none. It holds a rigid load beautifully and then, the moment the load settles or the timber dries out, it goes slack and stays slack. Polyester cord strap has controlled elongation — it stretches under shock and recovers, so tension survives the journey.
- Edge behaviour. Steel cuts. On coated steel, painted machinery, or timber, a steel band under load will bite into the surface, and by the time you see it the damage is done. Cord strap distributes pressure across a woven face.
- Handling and safety. Steel strapping under tension stores energy and releases it as a whipping blade when it fails or gets cut. Cord strap doesn’t. Anyone who has watched a steel band let go in a warehouse never forgets the sound.
Weight is a quiet cost too. A drum of 32 mm composite cord runs a fraction of the weight of the equivalent steel band — which matters when the strapping itself is billed as cargo on an air or LCL consignment.
Steps for Securing Heavy Export Cargo
- Weigh and calculate. Actual gross mass, not the drawing weight. Apply the acceleration coefficient for your worst transport leg.
- Assess friction. Know your surface pair. Add anti-slip mats where the number is poor — it’s the cheapest capacity you can buy.
- Position and block. Load heavy first, centre it, fill the voids with dunnage or bags.
- Select strap width from the required capacity, then add a safety margin. Don’t design to exactly 100%.
- Lash to fixed points only. Container lashing rings, not door hinges, not vent grilles. Yes, people do this.
- Tension in sequence. Work symmetrically from the centre outward so the load doesn’t get pulled off-square.
- Photograph everything. Wide shot, then close-ups of each strap and buckle. Costs two minutes. Wins claims.
- Re-check after the first move. If the container is shunted before departure, tension will have changed.
Common Cargo Securing Mistakes
- Lashing to the container’s corrugations or door frame instead of rated points
- Mixing steel and cord strapping on the same load, so one takes all the force
- Using one wide strap where two narrower ones would spread the load
- Ignoring the road leg entirely and securing only for sea
- Over-tensioning to compensate for the wrong strap width — this breaks packaging, not the laws of physics
- No anti-slip mats, ever, because “we’ve always done it this way”
That last one is genuinely the most expensive habit in the industry.
Frequently Asked Questions About Cargo Securing
Do I need a lashing calculation for every shipment? For repeat consignments, no — calculate once per cargo configuration and reuse it. For new cargo, changed weight, or a different route, yes. Surveyors and P&I clubs increasingly ask for it, and having it on file settles disputes fast.
Is composite cord strapping allowed for container lashing? Yes. Polyester composite cord strap with wire buckles is widely used for container lashing and is accepted under standard cargo securing practice, provided the system strength meets the calculated requirement and the strap is applied to rated lashing points.
How much tension should I apply? Enough to remove all slack and pre-load the system — typically 10–15% of the strap’s system strength for top-over lashing. More is not better. Over-tensioning crushes packaging and stretches the strap into its recovery limit before the journey even starts.
What’s the single highest-value upgrade for most exporters? Anti-slip mats plus the correct strap width. Together they usually cost less than one damage claim’s inspection fee.
Can I reuse cord strapping? The strap, no — cut it. The wire buckles, often yes, if they’re undeformed. Check the buckle jaw for spreading before reuse.
Summary: Key Takeaways
Secure against the number. Know the acceleration coefficient for your worst leg, buy friction where it’s cheap, bundle the load into one mass, and use a strap that keeps its tension after the third day at sea. That’s the whole discipline.
If you’re shipping heavy cargo and you’re not sure your current strapping is rated for it, send us the load weight and the route. We’ll tell you the width you need.
Amass Strapping Solutions has manufactured composite cord strapping, container lashing strips and wire buckles from Rajkot, Gujarat since 2012. We supply strapping systems from 13 mm to 32 mm, rated and tested, to exporters who cannot afford a cargo surprise at the other end.
Request a sample roll and a free strap-width recommendation for your cargo → amass-strap.com