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The key role of container stowage in maritime transportation

Picture this scenario: upon reaching your port of discharge, you realise the container you have to unload has been stowed incorrectly. As luck (rather Murphy’s law) would have it, it happens to be it at the very bottom of the stack. 

You end up moving hundreds of containers to get to the one that is to be discharged, which causes significant costs and a huge waste of time. And let’s not forget that stack collapses and accidents may happen while containers are being rehandled.
How can you avoid such a situation? The answer lies in proper stowage of cargo containers.

So, let’s start from the beginning…


You should never assume that the weather will be calm and the sea will be smooth during your voyage. In fact, you may face different weather conditions that exert different forces upon the ship and its cargo. As a result, containers may topple into the ocean or be damaged if they aren’t stowed properly.

Stowage is the art of packing and storing cargo safely and logically onboard a vessel. It aims to place commodities in a manner that will prevent damage caused by load shifts during transit.

Come to think of it, it’s all about safety, as proper stowage affords protection to:

  • Your vessel, ensuring it will be stable and seaworthy.
  • Your cargo, preventing it from getting damaged.
  • Your crew and stevedores involved in loading and unloading.

Let’s go one step further. How you stow your cargo will also be a determining factor to:

  • Maximise the cargo intake of your vessel.
  • Minimise discharging and loading.

But in order to achieve these two goals, you’ll have to gain an understanding of…


Remember the scenario we described at the beginning of this post? You could have prevented it by resorting to block stowage.

In practical terms, it’s a loading system whereby cargo is stored sequentially onboard a ship, i.e., all containers meant to be offloaded at a certain destination port are stacked together and marked accordingly.

This storing practice brings benefits, such as:

  • Cargo is loaded and unloaded easily by location.
  • Dangerous goods are segregated to prevent accidents.
  • Precious time is saved.
  • Expenses such as additional port charges or crew fees aren’t incurred.
  • Restowing isn’t necessary.


The efficient operation of a cargo vessel depends on its stowage plan. It’s thus a critical job that is performed by a stowage planner.

Experienced stowage planners may prepare bay plans manually. However, they now tend to use software, such as CASP, MACS3 and Bulko. These tools show cross sections of the vessel bay by bay, and provide a total view of the stow positions.


The stowage plan is the result of putting together the following data:

  • Ports of call in the order of rotation.
  • A summary of the number of containers to be loaded per port, segregated by size, type and weight.
  • A list of hazardous and Out Of Gauge (OOG) containers to be loaded from each port.
  • A summary of containers already on board.

Space is then allotted for each container based on this information and other…


  • Cargo should be loaded from bottom to top decks to make sure the vessel’s stability isn’t compromised.
  • Cargo planning should be done as per the latest cargo. Containers to be offloaded at the last destination are stowed at the bottom, whereas those for the nearest discharge should be on top.
  • Containers that weigh less are sometimes kept underdeck, in order to prevent the aggravated rolling of a ship.
  • Dangerous goods must be kept separately.
  • Shifting of units already loaded is to be minimized.
  • Standard lashing equipment and procedures can’t be applied to OOG loads. That’s why this sort of cargo shouldn’t be stored in outboard rows in order to prevent it from falling overboard if lashings break.

By following these guidelines, your cargo will be stowed safely and your vessel’s loading and unloading operations. However, there’s yet another aspect to consider.


When you ship cargo, you want to optimise the vessel’s carrying space and maximise your profit.

Broken stowage is cargo space that is lost or remains unfilled due to:

  • the shape of the vessel (e.g., curved walls or cargo bays)
  • varying shapes and sizes of the cargo and packages (e.g., round items)
  • material used to secure the cargo, such as lashings or dunnage (e.g., crates or airbags)


Here are some tips to minimise the amount of “air” you carry in the hold of your vessel:

  • Optimise packaging by choosing square or rectangular boxes, as opposed to round or odd-shaped cartons.
  • Select the right container when shipping general cargo.
  • Select the right vessel for break bulk shipments.
  • Minimise dunnage & lashings while ensuring the safety of your cargo.
  • Calculate stowage factor (SF) in advance – this ratio indicates how many cubic meters one metric ton of a particular type of cargo occupies in a hold.

In a nutshell, correct stowage planning is the key to optimising your cargo loading, while minimising costly risks, such as container collapses onboard your vessel.

If an oversight during this crucial process results in your cargo being damaged or lost at sea, we can help with every step of your claims handling. Find out more about the services we provide as TPAs.

We are Claimar, your Third Party Administration (TPA) management partner, skilled and expert in marine services.


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