It’s a story that is also taken up in the Gard Guidance on Freight Containers by Jeroen de Haas. The concept of an intermodal container was first proposed by McLean.
His “big box” idea, which has revolutionized cargo handling worldwide, came to him in 1937 while he waited most of the day to deliver cotton bales on his truck to a pier in New Jersey. “Suddenly it occurred to me: Would it not be great if my trailer could simply be lifted up and placed on the ship without its contents being touched?” De Haas goes on to explain that the subsequent development of container shipping in the 1950s and 1960s was largely an American affair featuring McLean.
Boxes similar to modern containers had already been used in rail applications. What was new in the revolutionary ideas presented by McLean was the belief that efficiency could be vastly improved through intermodal containers and his perseverance in making it happen.
McLean converted the World War II tanker Potrero Hills to a ship capable of carrying containers and rechristened her the Ideal X. She made her maiden journey on April 26, 1956, sailing from Newark to Houston carrying 58 metal containers and 15,000 tons of petroleum. By the time the ship had been unloaded in Houston, the company was already taking orders to ship goods back to Port Newark in containers, writes de Haas.
“Loading loose cargo on a medium-sized cargo ship cost $5.83 per tonne in 1956. McLean’s experts calculated that the cost of loading the Ideal X at 15.7 cents per tonne. With numbers like that, the container seemed to have a future.”
McLean grew into shipowning with his company Sea-Land. Initially the containers were loaded on their chassis, but later the chassis was left behind, enabling containers to be stacked. The first vessel to carry containers only was Sea-Land’s Gateway City which made her maiden voyage on October 4, 1957.