In A Nutshell
During World War II, the British needed a way to hunt German U-boats in the Atlantic Ocean because their land-based planes didn’t have the range. Since steel and aluminum was in short supply, they needed a different material with which to make their aircraft carriers. The proposed material was pykrete, a mixture of wood pulp and ice.
The Whole Bushel
In 1942, during World War II, German U-boats were sinking merchant ships with impunity because the Royal Air Force didn’t have the range necessary to scout for the Germans. In addition, they couldn’t afford to make conventional aircraft carriers because the steel and aluminum necessary for construction was in short supply. Geoffrey Pyke was a researcher who worked for Combined Operations Headquarters (COH) in Britain and suggested making an aircraft carrier out of ice because it required much less energy to produce and was plentiful. His proposal was passed along to Lord Louis Mountbatten, the Chief of COH, who then showed it to Prime Minister Winston Churchill, who was very enthusiastic about the idea. It was approved and given the code name “Project Habakkuk,” a reference to the biblical verse which reads: “Behold ye among the nations, and see: wonder, and be astonished: for a work is done in your days, which no man will believe when it shall be told.”
After researching his idea further, Pyke came to the realization that ice was an unsuitable material because it would melt too quickly and, after observing natural icebergs, noticed they had a tendency to roll over. The project would have been discontinued if a team of researchers had not come up with a new material, named “Pykrete” in his honor. Using a frozen mixture of wood pulp and water, he found it would melt much slower than ice and was considerably stronger as well. The only drawback was a large slab of pykrete would go through something called plastic flow or creep if the temperature exceeded -16° Celsius (3.2° F). To remedy this problem, Pyke proposed a series of insulating materials for the surface and a complicated refrigeration system. Happy with the research, the COH ordered a scale model built in Canada.
In 1943, an 18-meter by 9-meter prototype (60 ft by 30 ft), weighing in at 1,000 tons, was produced. It was kept frozen with just one single-horsepower engine. A full-size ship, measuring 600 meters (2,000 ft) long and weighing 1,800,000 tons, was ordered and scheduled to be completed in 1944. Complications involving the plastic flow problem, as well as supply issues, delayed the project, pushing the estimated finish date to 1945. Churchill, after discussing it with his advisors, as well as the Americans, concluded it wouldn’t be necessary that late in the war and would cost much more than originally anticipated (an increase of over £2,500,000.) In addition, the manpower it would take to build the ship could be used elsewhere more effectively and Portugal had agreed to let Britain use some of its airfields so Project Habakkuk was scrapped.