Every year, over 5,000 container ships sail the world’s oceans, carrying over 11 billion tonnes of cargo. That cargo is carried in shipping containers, which have to survive handling, sea waves, storms, and extreme temperatures.
Shipping containers are built to last for decades. But it’s not just about the design of each individual unit. To make sure that shipping containers are tough, safe, and long-lived, they also have to be secured properly. The art of container lashing includes various tools, skills, and systems to secure containers on cargo ships.
What is cargo container lashing?
Container lashing is the system used to secure containers in place on a cargo ship’s deck. Crews use ropes, cables, chains, and special types of locks to make sure that the containers don’t move or tip over during transport.
It’s an important and difficult job, so container lashing has strict regulations, set by international organisations like the International Maritime Organization (IMO) and the International Organization for Standardization (ISO).
How does container lashing work?
Before containers are loaded onto a ship, they’re fitted with stacking cones on each corner, which help stack the shipping containers and keep them in line. Depending on the size of the cargo, and the ship itself, containers can be stacked horizontally or vertically.
Once a crane has lifted the containers on board, the corner joints are tightened with lash bars. Next, lashing rods and turnbuckles are used to tie the containers to lashing bridges – long, steel structures that run across the ship to support the stacks.
Last of all, workers use lash spanners to tighten screws and make sure that every container is lashed securely. Any mistakes could lead to serious injuries or cargo damage.
Why is container lashing important?
Container lashing makes sure that shipping containers, and the cargo inside them, don’t move around during transport.
It’s used on every method of transporting shipping containers, including sea, road, rail, river, and air. Each mode of transport has its own regulations which have to be followed. Different kinds of cargo also have specific regulations, especially cargo containing dangerous goods.
The benefits of container lashing
As well as increasing efficiency, container lashing has many other benefits.
- Reduced damage to containers. Properly secured shipping containers cannot get damaged, and they’re less likely to damage other containers around them.
- Reduced damage to goods. When containers stay still, so does their cargo, which means fewer breakages.
- Reduced loss at sea. Container lashing reduces the risk of shipping containers falling overboard and getting lost at sea.
- Reduced injuries and fatalities. Shipping containers are large and heavy, so any accident is very serious. Lashing containers securely means there’s less chance of a container moving or tipping over and someone getting hurt.
- Reduced theft. Lashing secures containers and makes it harder for thieves to get access.
The challenges of container lashing
Container lashing is a complex system that needs skilled workers. It’s an endlessly variable job with a lot of different challenges.
The two main problems are:
- Securing cargo within containers to reduce movement.
- Protecting the structure of the container itself.
During container lashing, workers have to think about the type of cargo being transported, the likely weather conditions during the journey, and the cargo’s weight, size, and route. Each factor has an impact on the safest way to stack and lash cargo in place.
How container cargo lashing improves maritime efficiency
When container ships are far out to sea, amid huge waves, containers can easily fall overboard. They’re unlikely to be recovered unless someone notices right away. Container lashing reduces the risk of loss or damage of containers. That means less financial risk for shipping companies, shippers, and consignees.
Container lashing equipment
Cargo lashing uses a set of specialist tools, described as lashing equipment. There are three different ways to secure cargo inside a vessel, which are described in each ship’s Cargo Securing Manual.
Fixed equipment
Fixed equipment is welded to the ship’s deck and serves as a foundation for the containers to be secured. This equipment mainly consists of sockets and D-rings that hold the cargo securely in place.
Loose equipment
Loose lashing equipment works with the fixed equipment to hold stacks of containers in place.
Loose lashing equipment includes:
- Lashing rods and bars – which link containers to the ship.
- Turnbuckles – which hook containers to the lashing rods.
- Stacking cones – which help align containers when they’re stacked horizontally or vertically.
Ro-Ro lashing equipment
“Ro-Ro” is short for “roll-on, roll-off”. This is the equipment used on ships that carry wheeled cargo such as trucks. It includes trailer webbing, lashing chains, and trailer chocks to hold wheels in place.
What are the different types of container lashing?
As well as the main types of equipment, there are also four different types of locks used in container lashing to hold containers still.
Twist locks
Twist locks are the most common type of container lashing. They work just the way the name suggests: two bars are twisted together, locking them in place so that they can’t move.
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View productsTurnbuckles
Turnbuckles are used to control the tension or length of a cord, cable, or rod. They’re also called bottlescrews or rigging screws. The turnbuckle is connected with a bolt or hook at either end. By turning the rod between the two bolts, you can ratchet up the tension on a cable to secure a load.
Ratchets
Ratchets allow you to pull a rope or cable in one direction, but stop it from being pulled back the other way. Think of a zip tie, which you can close but not open. Ratchets are often used alongside twist locks for extra security.
Each ratchet has a wheel with teeth, along with a small device called a pawl or ratchet which makes the teeth bite down when the rope starts to move in the wrong direction.
Camlocks
Camlocks are used to secure two ropes or chains together. They get their name from the two cam-shaped plates which fit together to make the lock. Similarly to a ratchet, it lets the ropes move in one direction, but not the other. They’re also often used in combination with other types of locks.
Steps for lashing containers
To make sure that containers are properly secure, everything has to be double-checked before, during, and after container lashing.
Normally, the process of container lashing involves the following steps:
- The ship is checked for safe lashing points and lashings. Everything should be in good condition before loading starts.
- The container is moved onto the ship’s deck by crane.
- The lashings are placed around the container to secure it and support its weight.
- The whole cargo is inspected once all the containers are in place.
Who carries out the lashing of containers?
The workers who carry out container lashing are called stevedores. However, ship’s crews also often get roped in to help – it’s usually the crew that de-lashes a cargo when the ship arrives at its destination.
Container lashing safety advice
Container ships can be dangerous places. They’re stacked high with heavy metal containers, constantly in motion, and often in harsh weather conditions.
Following safety best practices is absolutely essential.
Ensure all personnel are properly trained and certified
Whether they’re stevedores or ship’s crews, everyone involved in container lashing should be fully trained.
Use appropriate personal protective equipment (PPE)
Everyone involved in container lashing should wear a safety helmet, gloves, reflective vest, and safety shoes. Back support belts are optional, but recommended for any heavy lifting.
Check all equipment
As we’ve discussed, every piece of equipment should be checked before lashing, from twist locks to the ship itself. Fixed lashing equipment, the ship’s railings, catwalks, work platforms, and steps should also be inspected regularly.
Follow the manufacturer’s instructions
Manufacturers’ instructions for lashing containers are laid out in the Cargo Securing Manual which every shipping vessel has to carry. It’s important to know the instructions thoroughly so that you don’t miss any maintenance issues or malfunctions.
Always use the correct number and size of lashings for each container
Each container has a specified number and size of recommended lashings. Placing a container carelessly, or skimping on the lashings, could result in movement, damage, or loss of containers.
Check the weather and sea conditions
It’s a good idea to check the weather conditions before container lashing starts. Container ships can take a lot of punishment once they’re ready for a voyage – but high winds or waves during the container lashing process could be dangerous.
Communicate clearly and effectively
Accurate, timely communication reduces the chance of mistakes or accidents. Everyone involved in container lashing should have a way to communicate, including the crane operator and the ship’s crew.
The bottom line
Container lashing is a complicated system that requires specialist equipment and crew. Done right, it can protect shipping from loss, damage, and inefficiency. However, it’s very important to check equipment regularly, follow regulations, and wear safety equipment during the process.
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