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What is the maximum overheight allowed when loading 40′ open top or flat rack..??

One of the readers of this blog Youri asked the question “What is the maximum overheight allowed when loading 40′ open top or flat rack..??“..

Let me refresh what OOG, Open Top (OT) and Flat Rack (FR) is..

Out of gauge Cargo (OOG) : Cargo that extends over and above the standard measurement of a General Purpose container.. OOG cargo is normally carried in Open Top containers (OT), Flat Racks (FR), Platforms (PL) due to the nature and size of the cargo..

Open Top Container – comes in 20’ & 40′ – Used for cargo that cannot be easily loaded through the door and needs to be loaded from the top.. The cargo could also be ingauge.. This type of container is also used for loading cargoes that are over high.. Used for the carriage of cargoes like machinery, steel or cement pipes, glass etc..

Flat Rack Container – comes in 20′ & 40′  – Used for cargo that is over width, over length and/or over high or cargo that cannot be loaded through the top like an OT or through the door (cargo may also be within gauge)..

Big machinery, vehicles on tracks, big reels etc can be loaded on this type of container.. The cargo could also be ingauge, but is heavy and requires a forklift to load it.. In certain types of flat racks, the ends can also be folded – and they are known as Collapsible Flat Racks (COFL) also known as Platform..

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Images are courtesy of Hapag Lloyd..

Apart from above, you also get Super Rack containers which I covered in one of my previous articles about unusual and different container types..

Super-Rack container – Similar in use as a Flat Rack container but with a BIG difference.. The difference is that in a Super Rack container, the corner posts can be extended upwards to increase the height.. This is most useful when you have Overhigh cargo..

Generally when you load an overhigh cargo on a Flat rack, slings will need to be used to lift the container as the spreader cant lock onto the corner posts..

With the super rack, you can lift the container directly without any slings as the below images will demonstrate..

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Images are courtesy of Super Rack who are the inventors of the above height-adjustable flat rack container..

So how high or how wide can I load cargo on a FR or how high can I load a cargo on an OT..


There is no real set limit on the Out Of Gauge that an OT or FR can take.. The capacity of the container is dependent on the weight and not really on the height or width..

When there is an OOG cargo for shipment, the client is required to send

  1. the full details of the cargo
  2. the complete dimensions of the cargo
  3. the weight of the cargo
  4. pictures or drawings of the cargo

The reason for this requirement is so that the ships planning department and/or ships chief officer etc can check the suitability of the cargo to be loaded on the ship and advise the client if it can or cannot be loaded..

So sometimes if you feel that the shipping line is taking too long to confirm the acceptance of the cargo, please remember the steps they have to go through..

Such information becomes all the more important if you are planning to load some extreme OOG cargo or project cargo as below

extreme oog

extreme oog

As you can see, this extreme overwidth cargo is loaded on FR on board the ship.. Both cargoes are being loaded on several FR containers in tandem..

Images are courtesy of Hapag Lloyd..

Therefore, as long as the cargo

  • does not obstruct visibility when loaded on the ship (in case of loading on deck)
  • does not affect the safety of the ship/crew
  • is within the limitations of the port, country of export/import

there is no set limit for OOG..

See below examples where some seriously over high cargo loaded on FR are handled using a variety of equipment

  1. Spreaders with overhigh frame
  2. Spreaders with slings and elephant hooks/top lifting lugs
  3. Spreaders carrying cargo loaded on super racks

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You can also see it in action here

and here

If you have had any experience with OOG cargoes where you had to use some creative solutions to load or discharge using open top or flat rack containers, please do share..

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Hariesh Manaadiar
Hariesh Manaadiarhttps://www.shippingandfreightresource.com
I am Hariesh Manaadiar, the Founder of Shipping and Freight Resource.. I have been in the dynamic shipping and freight industry for over three decades and have worked in several sectors.. I share my experiences and knowledge of the industry through this blog for those looking for help in the industry.. Stay subscribed for more free useful content about shipping, freight, maritime, logistics, supply chain and trade..


  1. Sir, We have an oversized machine which can be only shipped on the Flat rack . The machine cannot be enclosed with the wood box. As such, please let me know if there will be damage to the machine if wrapped properly in plastic or shrink wrapped materials.

    Please reply

    • Hi Mishma, in your own interest, I would strongly recommend you employ the services of a cargo surveyor who can guide you properly based on the cargo specifications.. That would be the best option for you to avoid any damage to your cargo..

  2. I must seriously say that you probably have the nicest resource of freight shipping online. I must say that even I learn something new I come here.

    Waiting for more!

    • Thank you so much, such a great source.
      I am wondering if this is a fundamental rule for all shipping companies or it depend from one to an other.

    • Hello Zeli, the basics remain same in terms of container dimensions and the process followed, but even with the same shipping line, things concerning OOG will be different from vessel to vessel depending on the physical cargo on board the ship, space, ship rotation etc..


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