Open-top Containers may seem ordinary, but their importance cannot be underestimated: they are often the only practical way to transport oversized cargo. However, this also brings significant challenges, as you will find them harder to procure than standard dry ISO containers.
The reason is simple—there are far fewer of them compared to standard containers. Shipping companies typically only order dozens or even hundreds of open-top shipping containers, whereas they need thousands of standard ISO containers. Consider the Drewry’s composite world container index… plus the additional 25% cost of open-top shipping containers, and it's not hard to understand the reason.
But that's not the only reason. Since open-top shipping containers might be too tall, they can't be buried deep within stacked containers and are exposed to the environment at the top. Thus, these container world's "convertibles" are seen as "special cargo" by shipping companies. This also means that there are relatively few booking options due to the limited "top spots" for each voyage. Unfortunately, all of this is reflected in higher prices.
This is especially true when container ships load a large number of open containers (such as dry cargo containers) and wait to be unloaded at crowded container ports. —All containers are caught in a massive traffic jam (calculated in TEU).
Although the roof is covered with a waterproof cloth (rather than ordinary weather-resistant steel), open-top shipping containers must meet the same waterproof standards as any other dry cargo container as per ISO standards. Remember, they will be positioned at the top, exposed to natural elements.
Nonetheless, it's important to recognize the fact that the only thing separating your cargo from the natural environment is the waterproof cloth, usually fastened in place by metal TIR ropes threading through eyelet-protruding D-rings.
If your cargo is scrap metal (a typical load for many open-top shipping containers), then you may have nothing to worry about. However, if you are meticulous, especially if you are shipping a large and expensive piece of machinery simply because it is too long and heavy to be forklifted into a normal dry environment, you may need to consider additional waterproofing measures.
For open-top shipping containers, security can be a particular concern. Although the waterproof cloth cover is theoretically as waterproof as ISO dry boxes, in practice, they can never achieve the same level of waterproofness. Obviously, a simple utility knife can easily cut through the waterproof cloth.
The customs seal on the TIR line offers minimal deterrence to an intruder with a knife. With a quick cut to the waterproof cloth, they can easily gain entry. Moreover, they can re-bond the cloth after removing the goods, making it look like a simple repair.
If security is a concern for you, a hard-top open-top container might be the ideal solution. It offers all the robustness of a standard ISO dry cargo container... but with a removable steel top. These roof sections can be quickly accessed by forklift for easy loading and unloading. The great advantage of the hard-top open-top container is that, while the roof panels can be removed for easy access, the dimensions remain the same as a regular container. Therefore, it can be placed anywhere on the ship. You don't have to pay a premium for the top-tier VIP spot.
But all of this assumes your cargo is bulky and difficult to load, but not overly tall. If the shipment is too high, then you may still need to pay extra, as you will have to specify containers equipped with waterproof cloth.
