Salvage Shipping Containers Using Twistlocks

In "Don't abandon ship! How to salvage a mega-vessel" (New Scientist, 26 November 2013), Will Gray describes the problems with salvaging cargo from mega-container ships. As they point out, without the ship upright the containers can be difficult to remove. However, Gray mentions chains having to be placed around the container to lift them, which I don' t think should be necessary. Standard shipping containers have three slots in each corner designed to fit a "T" shaped Twistlock connector. The containers are designed to be lifted, fully loaded, using the four connectors on the top face. The twistlocks can be attached by hand, or with a remote mechanism on a crane. It should be possible for a diver to attach a twistlock by hand to a submerged container, or for this to be done by a remotely operated underwater vehicle (ROV).