©2014 This excerpt taken from the article of the same name which appeared in ASHRAE Journal, vol. 56, no. 7, July 2014.
By Joseph W. Lstiburek, Ph.D., P.Eng., Fellow ASHRAE
About the Author
Joseph W. Lstiburek, Ph.D., P.Eng., is a principal of Building Science Corporation in Westford, Mass. Visit www.buildingscience.com.
Ballast is necessary in ships for stability, balance, trim and to otherwise keep them upright because the alternative is not pleasant. The amount of ballast necessary varies based on the type of ship and the amount of cargo if any. Legend has it that many buildings and roadways in the Colonies were constructed out of brick and cobblestones that came over from Europe as ballast on ships. Alas, it is only a legend, as the vast majority of buildings and roadways were constructed out of native bricks and cobblestones. Not enough ballast came over to make a significant dent in the infrastructure of the time.
But enough came over to end up in a few historic landmarks and provide fodder for the legend. The main reason this type of ballast came over was because more cargo went east to Europe at the time than the other way around. How times have changed, now more comes to America than leaves. Hold that thought for later.
More recently, in this past century, ballast from England was instrumental in the construction of a New York City landmark. During the Second World War the United States provided an Atlantic lifeline to England supplying men and materials for the war effort. Canadians escorted the allied convoy ships and for a time Canada had the third largest navy in world. Many of the convoy ships disembarked in Bristol, England, a major port city. The ships “had no British goods to replace them on the return trip, and needed ballast for stability.” The Luftwaffe solved the ballast problem by bombing the city to near devastation. The brick rubble from the Luftwaffe bombing provided the ballast for the empty convoy ships returning to America. In New York City this ballast was used to build East River Drive.
Our story now takes us to North Carolina and a local “good ole boy.” Malcom McLean, armed with a high school education, bought a secondhand truck from savings earned pumping gas and started a trucking company that ended up changing the world. He wanted a way to move cargo on ships without having to unload his trucks. He figured he could just load his trucks onto ships, strap them down, and be done with it. That didn’t work very well. But this “good ole boy” didn’t give up. He needed an engineer to make things work. An old school engineer. My kind of engineer.
Keith Tantlinger, a mechanical engineering graduate from the University of California, Berkeley who worked for the Douglas Aircraft Company during the war building B-17 bombers, solved McLean’s problem. Disconnect the truck payload from the truck chassis. Have a bunch of stackable boxes that could go from a truck chassis onto a railroad car or onto a ship. This was not a new idea, but Tantlinger made it work by designing the boxes and the method of securing the boxes and the method of lifting the boxes. He created the “intermodal freight container.” Intermodal because it went from ship to rail to truck without unloading and reloading the contents. Today, we call it a “shipping container” (Photo 1).
What was so special about Tantlinger’s box? He created a “twistlock” that was a rotating connector that locked into a corner casting built into the eight corners of the box (“cube”). Each box had strong corner posts so that they could be stacked. The ability to stack the boxes and secure the boxes to a “bed” and also to each other was revolutionary. The “double cone” twistlock became a staple in the shipping and transport industry and “stack and lock” containers dominate to this day. Tantlinger also developed a container spreader bar. A stevedore was no longer necessary to attach ropes to lift and move the containers. This forever endeared Tantlinger to the International Longshoreman’s Association.
So, how do shipping containers and ballast tie together? If the ships carrying the shipping containers are sailing with full shipping containers the ships don’t need a lot of ballast. If the ships carrying the shipping containers are sailing with empty shipping containers the ships need a lot of ballast. Duh.
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