Project Habakkuk: The Aircraft Carrier Made Out Of Ice

Photo Credit: BBC Future / BBC Video

The Battle of the Atlantic was the longest-running campaign of WWII. The Germans had seized control of the mid-Atlantic, using U-boats to sink merchant and passenger ships. The British wanted to ensure the safety of transatlantic travel, and the possible solution was called Project Habakkuk.

An aircraft carrier made out of ice

Project Habakkuk came from the mind of scientist Geoffrey Pyke. Pyke worked at the Combined Operations Headquarters, a department within the British War Office. He was seen as a brilliant mind and had the support of Prime Minister Winston Churchill, Admiral of the Fleet Lord Mountbatten, and Irish scientist J.D. Bernal.

Pyke came up with the idea for the aircraft carrier while in the U.S. organizing the production of M29 Weasels for Project Plough. He’d been looking for a cheap and effective way to protect ships out of reach of the Royal Air Force (RAF) patrol, as steel and aluminum were in short supply. His answer to this problem was ice.

Geoffrey Pyke
Geoffrey Pyke. (Photo Credit: Dark Docs / YouTube)

According to Pyke, ice could be manufactured with one percent of the energy needed to produce an equivalent mass of steel. As it was considered virtually indestructible at the time, he proposed that an iceberg — either natural or artificially made — be leveled on top to create a runway and hollowed out to allow for storage.

It would be 2,000 feet long by 300 feet wide, with a draft of 150 feet. If everything went according to plan, it could carry 100 twin-engine bombers and 200 fighter planes.

Wood pulp is thrown into the mix

Churchill was enthusiastic about the proposal and wanted work to start immediately. In early 1942, Pyke and Bernal asked molecular biologist Max Perutz to determine if such a ship could withstand the conditions of the Atlantic. Perutz, with his knowledge of ice and glaciers, pointed out that natural icebergs had a tendency to roll over without warning. They’d also be too small for an airstrip.

To create a more stable ship, Pyke decided to use Pykrete, a mixture of 14 percent wood pulp and 86 percent water. It could be machined like wood and cast into shapes like metal, and would create an insulating shell when placed in water. With wood providing reinforcement and ice acting like steel rebar, Pyke claimed it was stronger and more bulletproof than regular ice. There was also the added bonus that it would melt slower and not sink.

Plans for Project Habakkuk
Photo Credit: Unknown Author / Wikimedia Commons

Perutz was quick to point out that issues would arise if the pykrete wasn’t cooled to -16 degrees Celsius. To try and work through these deficiencies, he conducted experiments below the Smithfield Meat Market in London.

Eventually, he surmised the ship could be built out of pykrete only if its surface was protected by insulation. It would need an onboard refrigeration system and ducts to ensure the temperature was evenly distributed.

Building the Habakkuk in Canada

Neither the U.S. nor the British Navy wanted to take part in the Habakkuk’s construction, so it was decided a prototype would be built at Patricia Lake in Jasper National Park, Alberta, Canada. The ice blocks would be produced at nearby Lake Louise, and the construction would be done by conscientious objectors from Canada.

Pyke assured Churchill the carrier could be built in as little as 14 days and could be completed by 1944. The prime minister ordered one ship, with a promise of more if the first was successful. While the initial cost of production was slated to be £700,000, it ballooned to £2.5 million. The Canadians also thought it impractical to build the ship during the spring, with the warm weather ahead. That, paired with warnings from Perutz, made Pyke and Bernal realize they couldn’t meet the 1944 deadline.

Panoramic view of Patricia Lake
Patricia Lake in Jasper National Park. (Photo Credit: BingWang / Wikimedia Commons CC BY-SA 4.0)

As work progressed, so too did the demands regarding the carrier’s capabilities. The British Navy wanted it to have a range of 7,000 miles, with a torpedo-proof hull and the ability to withstand high waves. It also asked that a rudder be installed for steering purposes, going against the initial plan of using motors to direct the ship. This posed an issue, as the rudder would need to be 100 feet tall, and a solution was never found.

As problems began to mount, naval architects set to work on drawing up three alternatives to Project Habakkuk’s initial design. In August 1943, they presented their results. While most leaned toward the second one, none appeared to be the right solution.

The project is shelved

The growing list of concerns eventually led to the abandonment of Project Habakkuk. The prototype’s completion in 1944 confirmed that construction would be too costly. It was also found that the amount of material needed to build it would be more than an entire fleet of aircraft carriers.

Lord Mountbatten withdrew his support for the project. His reasoning surrounded outside events that had taken place during the carrier’s construction. Portugal had allowed the British to use its airfields in the Azores, and long-range aircraft had been introduced. As well, the country’s navy had begun escorting merchant ships across the Atlantic, in the hopes of protecting them from German U-boats.

Portraits of Max Perutz and Lord Mountbatten
Max Perutz and Lord Mountbatten. (Photo Credit: 1. Associated Press / Wikimedia Commons 2. British Official Photographer / Wikimedia Commons)

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In December 1943, a final meeting was held, during which it was concluded that “The large Habakkuk II made of pykrete has been found to be impractical because of the enormous production resources required and technical difficulties involved.”

The prototype took three summers to completely melt, with its metal components coming to rest at the bottom of Patricia Lake.