The plan to construct an aircraft carrier out of pykrete (a mixture of wood pulp and ice) was known as "Project Habakkuk" during WWII.
I am the former artist that created all the U-Haul graphics, I worked with many scientists & historians to design the Alberta graphic. (Photo above) a 1943 copy of a "Top Secret" blueprint they gave me to use as reference to create the ship you see on the trucks.
In the end, project Habakkuk was scrapped thanks to a confluence of circumstances. Its increased steel demands were too high, new airfields had reduced the need for carriers, longer-range fuel tanks were helping aircraft fly further, and the war was coming close to an end.
There is a little man hidden in the Habakkuk graphic, in fact I have hidden this man in all the graphics over the past 15 years.
The character is known as "Sammy U" within the company walls. I am sharing his location with you...
If you click on the image to the left, it will take you to a cheat sheet I have made that shows all the hidden spots, in every graphic!