Container lashing is the safety process of securing containers on cargo ships. It’s the most essential part of any shipping process, as it guarantees the cargo’s safety and ensures the well-being of workers aboard the ship.
In this article, we’ll explain in detail all you need to know about container lashing, from the different types of container securing equipment, lashing materials, and container stacks. Stick around.
What Is Container Lashing?
Container lashing is the process of safely securing shipping containers on the cargo ship.
The shipping containers are loaded onto the cargo ship, then they’re secured together with the containers below them and into the ship’s structure itself.
Container lashing is done using different cargo securing equipment like twist locks and lashing rods.
Twist locks are inserted into the elongated holes of the container’s corner casting, causing the rotating lugs of the locks to engage. This locks the containers together and secures them well into place.
Composite strapping and dunnage bags are also used to prevent goods from getting damaged by heavy impact during the lashing or shipping process.
Container Lashing Equipment
The process of container lashing involves the use of different equipment, including:
Base Twist Locks
Shipping containers are loaded over base twist-locks to ensure that the container wire handles are properly locked into position.
Semi-Automatic Twist Locks
emi-automatic twist locks are used in between two containers stacked on top of one another to form a stack between them.
Lashing Belts
A lashing belt is used to fix the cargo within containers into place during transportation. They’re secure and weigh significantly less than wires, chains, and jute ropes.
Lashing Rods
These are rods of various lengths tied to the container from one end and the ship deck from another
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In combination with the turnbuckle, the lashing rods are used to put tension on the container lashings.
Turnbuckles
Turnbuckles are used to adjust the tension on the container lashing.
A turnbuckle has two screw ends; one end is screwed to the lashing bar that’s connected to the container’s corner casting, while the other is welded directly into the ship’s deck.
Corner Casting
Corner castings are three-holed steel blocks that are placed in the corner of all shipping containers. They are used to lift containers, as well as connect them to one another and to whichever mode of transport they are on.
Emergency Tool
This is used in case of a twist lock malfunction. The emergency tool allows for the twist-lock to remain open while lifting the container.
Grease
This is a thick, oily substance that’s applied to the lashing equipment to ensure the equipment is well maintained and properly operational.
How to Choose Container Ship Lashing Equipment?
There are two factors that influence the decision of choosing lashing equipment:
- The kind of cargo that needs to be secured (container cargo, liquid bulk, dry bulk, etc.)
- The kind of load carrier responsible for carrying the cargo (road, rail, seaway, etc.)
What Are the Markings on Lashing Equipment?
The markings on lashing equipment include:
Lashing Capacity (LC)
This indicates the lashing value in case of direct lashing or loop-lashing.
The unit used for valuing web lashings is daN, while kN is used for valuing chain lashings.
- 1 daN ≈ 1 kg
- 1 kN = 100 daN ≈ 100 kg
Standard Hand Force (SHF)
This indicates the standard handling force ideal of the ratchet, which is typically 50 daN.
Standard Tension Force (STF)
This indicates the tension force created by the SHF and transferred to the web lashing. This is used to decide whether top-over lashings are needed or not.
Webbing and Chain Identification
This indicates the material the webbing is made of, as well as the grade used in making the load binder and chain. This information is found on the label or marking tag.
Breaking Strength (BS)
This indicates the point at which any part of the cargo strap or rigging will fail. In other words, it’s the maximum force a new lashing can withstand in a straight pull without breaking or failing.
Cargo Lashing Methods
There are three methods for securing any kind of cargo. One or a combination of these methods must be used on a container vessel when securing any cargo.
- Blocking
Blocking is a cargo securing method that involves arranging neighboring stacks in such a way to prevent them from moving around during transport.
Metal or wooden wedges are used to keep containers in place. Also, cushions and extra layers of wood are used to cover the inside of the containers and act as a protective wall.
This method is very common in securing fragile or sensitive cargo like glass or liquids.
- Locking
Locking is the use of mechanical locks to secure different types of cargo into place.
It’s the most effective method of securing cargo and is a mandatory requirement in most freight forwarding and courier services.
Since locking is a very effective securing method, it’s used for all kinds of cargo goods and is a fundamental security measure.
- Lashing
One of the primary methods of securing cargo is lashing. This involves using binders, winches, and chains to keep cargo in place and prevent it from moving around during transport.
Lashing can be used both outside or inside the cargo, ensuring the maximum level of security.
Why Is Container Lashing Essential?
52% of the container shipping industry is sea-based, making it the highest and most important means of trading.
Since seaway is the primary means of cargo transport worldwide, ships are always subject to the harshest weather condition, making container lashing very critical. In fact, there were 1382 shipping containers lost at sea every year between 2008 and 2019.
When cargo is transported by sea, intense weather conditions and strong wind likely cause three main ocean motions: heaving, rolling and pitching. When these movements occur, they act as a force that affects container frames and their lashings.
If the container lashings aren’t done correctly and the cargo isn’t safely secured during transportation, there’s a high risk of shipping accidents.
Containers might fall overboard into the ocean, inflicting damage to other nearby cargo, to the ship itself, or, more importantly, endangering human life onboard.
Container lashing is the most essential part of shipping via sea, as failing to properly secure containers not only endangers property and human lives but also the environment at sea.
How Tight Should Container Lashings Be?
As a general rule, container lashings should always be tight, as slack lashings are never desirable. However, stevedores and the working crew should never use excessive force to over-tighten the lashings.
While it may seem counterintuitive, over-tightened lashing could be just as dangerous as under-tightened lashing. Over-tightening can cause the lashing rods to come under extra strain, increasing the pre-tension and causing failure under load.
Who Does the Container Lashing?
Stevedores are the ones responsible for lashing and de-lashing shipping containers in the docking port. However, due to time constraints and the ships’ desire to spend less time in ports, the deck crew can also work on the container lashing process.
Before docking at the port, the deck crew starts de-lashing the containers. This allows the containers to be discharged immediately after docking, saving time and money.
Regular checks on the shipping container lashings are also required by the ship crew to prevent the risk of any accidents.
Why Do Containers With Bad Lashing Fall Overboard?
Ships are constantly exposed to rough weather conditions, which put extreme forces on the shipping containers and the vessel itself.
Failing to carry out container lashing properly is one of the most common causes leading to containers falling overboard.
It’s also worth noting that the bigger the ship, the higher the chances of containers collapsing. This is because bigger ships usually carry way more cargo while being much less agile in the face of hard weather conditions, making them more susceptible to rolling and heaving.
Weight distribution among the ship’s deck is also a major factor that influences the ship’s motion at sea. As these motions become more aggressive, the falling of containers with bad lashing becomes more likely.
Shipping containers suffer a lot of wear and tear during their lifetime due to excessive loading and rough handling, which weakens their structure significantly. A damaged container may lead to accidents and cause unforeseen complications aboard the cargo ship.
Is the Carrier Liable in Case of a Shipping Accident?
What determines whether or not the carrier is liable for loss or damaged cargo is whether the carrier breached their duties under the international conventions of the sea shipment contract, or whether the cargo was damaged due to circumstances beyond the carrier’s control.
The carrier is obligated by law to properly load, stow, and carry cargo. If the cargo was shipped in good condition but discharged with any damage, the carrier is required to prove that the damage occurred without fault of the ship or that it was caused by perils beyond their control.
Can Shippers Use Their Own Containers?
When it comes to international trade, most buyers and sellers usually lease containers from carriers to export or import their cargo. However, some buyers/sellers prefer to use their own containers, which are called shipper-owned containers (SOC).
Benefits of Using Shipper-Owned Containers
- Lower cost of shipping cargo
- Gives the shipper more control over their shipments
- Avoid detention and demurrage fees
- Containers could be used as a storage space when not in transport
Drawbacks of Using Shipper-Owned Containers
- Money and time need to be spent on maintaining and repairing the containers
- Mandatory paperwork is required to prove that your shipper-owned containers are suitable for cargo transport, which could be a hassle
- Shippers need to find a space big enough to store their container when it’s not in use
Bottom Line
Despite all the technological systems available today, container lashing is still a largely manual process that requires the hands-on involvement of many workers on deck and aboard the ship.
It’s a hazardous operation that requires said workers to follow instructions thoroughly to secure shipping containers properly into the ships, prevent any accidents, and ensure safe transport of all cargo.
