A giant aircraft carrier made of ice? A giant aircraft carrier made of ice.

Written by: Sara Bohuch, BA Archaeology (Simon Fraser University) , MSc Conservation Practice (Cardiff University) 

In terms of places rich with classified war time projects and military intrigue, Alberta is rarely the first spot that people think of. But history holds no bias in terms of where it takes place, and Alberta had its own part to play in the eccentric branch of the military arms race circa WW2. This was in part due to the plentiful excess of one of Canada’s most abundant and hated elements: ice. 

In 1943, the Chief of Combined Operations for the British War Office had a point to prove about ice. His name was Lord Mountbatten, and he sincerely believed that ice could be used to defeat the Nazi menace during WW2. To establish his argument, he brought two huge chunks of it into the 1943 Quebec Conference. The secret conference was host to the likes of Winston Churchill, Franklin D. Roosevelt and William Lyon Mackenzie King, and Mountbatten had to justify the validity of his ice-related project to the leaders and their staff.

In front of a skeptical crowd of WW2 brass, he set up two ice blocks right next to each other. The first block was pure ice, while the block next to it was a new manmade composite mixture of ice and wood pulp. He retreated to the other side of the room, removed his gun, and shot a bullet into the first ice block. It predictably shattered to pieces. Mountbatten then reloaded his gun, took aim at the second block, and fired. This time, the bullet could not penetrate the ice, instead ricocheting completely off the block, flying through the pant leg of a nearby admiral, and ending up in the wall. The new material remained remarkably intact.

Artist’s rendering of what would be Project Habbakuk. Source: cnn.com.

Sources are mixed as to whether the above story is 100 per cent true, but Lord Mountbatten’s ice project was very real. The project was called ‘Habbakuk’, and its goal was to help win the war. At the time, fighter planes from North America could not make the full trip across the Atlantic Ocean without a refueling stop. This was usually accomplished by way of aircraft carriers or allied ports. The problem with both was that they presented a tempting target for Nazi submarines, and a single well-timed torpedo could be devastating. One theory put forward by war-time scientists was that if a new type of torpedo proof ship hull could be invented, then more war planes could be sent safely over to Europe. The increase in available aerial power would make a huge difference in the war effort.

In the early 1940’s, an inventor named Geoffrey Pyke came to Lord Mountbatten with an interesting newfound material that not only would work but would not need to exhaust the already taxed metal reserves. Pyke was known in for being an eccentric genius, with other projects of his design including a plan that took soldiers, drugged them, and shot them through a tube into enemy territory. Pyke felt that he was onto something new with this type of ice he had developed and called ‘pykrete’ (named after himself). This material would became the same mixture of ice and wood pulp that Lord Mountbatten later shot at in a Quebec conference room.

Mountbatten was so impressed by the material Pyke presented that he agreed to sign onto the project and further its development. Numerous secret trials were conducted at the Smithfield meat market in London (behind a false wall of meat no less!) to get the pykrete material proportions right, and when they concluded Mountbatten was keen to go all the way and build a ship from the substance. He later took a block of pykrete to Winston Churchill himself, bursting into Churchill’s bathroom while the prime minister was in the tub, and throwing it into the bathwater alongside the naked man to demonstrate its melting properties. Admittedly these properties are quite interesting, because the wood pulp keeps the inner parts frozen while the outer melts exceedingly slowly. Churchill was also impressed and greenlit the project after his bath.

Design plans for Project Habbakuk. Source: mountainculturegroup.org.

Once Project ‘Habbakuk’ was approved, Pyke, Mountbatten, and a legion of scientists set about beginning to make a 1 to 50 scale model ship of the aircraft carrier from the new material. They settled on Lake Patricia as a test site, a cold-water lake in Alberta near Jasper. Using enforced labour from a nearby war camp of conscientious objectors (who were never told what it was they were building), the project began.

The prototype ship constructed on the waters of Lake Patricia was sixty feet long and thirty feet wide. It weighed roughly 1,000 tons with a hull made from pure pykrete, which was kept frozen by a 1-horsepower motor. It also had a tin roof attached to the top, effectively disguising the project as a boathouse. Lord Mountbatten did eventually shoot this one as well, this time with a shotgun, to test hull integrity. The bullet didn’t even make a scratch. After that, he took his ice samples with him to the Quebec Conference and repeated the demonstration.

As was shown in Mountbatten’s extreme gun-based examples, ice as a material is exceptionally brittle and does not respond well when shot. Mixing another material into the water when it freezes, such as wood pulp, reinforces the material in the same way that rebar strengthens concrete. The resulting product can not only stop bullets or torpedoes, it can be molded or carved into whatever shape needed. Not only that, when used as a building material, any damage to it can be swiftly repaired with water and refrigeration units.

As intriguing as the material properties were, Project Habbakuk ultimately failed. The thing about building a ship out of ice was that it only worked provided that the ice could be kept cool. The cost of building the necessary refrigeration machinery in a few of these ships would be more then an entire fleet of standard aircraft carriers. That, combined with the fact that by 1944 most planes had larger fuel tanks and thus no need for a mid-Atlantic fuel up, made the ice hulled aircraft carrier redundant. The project was stopped, the model stripped of its refrigeration equipment, and all else was left to melt into the bottom of the lake. It took three years to melt completely, and the underwater remains would not be rediscovered until the 1980’s.

Remnants of Project Habbakuk still lie at the bottom of Lake Patricia…for now. Source: combinedops.com

In 1982, underwater archaeologist Susan Langley heard a conversation about, “an airplane made of ice” up in Alberta’s Lake Patricia. Like most divers who hear, “sunken aircraft” and “made of ice”, the temptation to see for herself was unbearable. Discovering that the rumored plane was actually a ship did not dampen her curiosity in the slightest, and in 1984 she made the dive in person. The wreck site sits roughly 100 feet below the surface, with low visibility and cold temperatures to contend with (not to mention a seasonal algae bloom in the summer). But none of that mattered. What Langley discovered at the bottom of the lake, and the strange history behind its remains, inspired her to write her PhD dissertation and a book on it. Since then, a small but steady stream of divers come to the shores to behold the wreckage of Alberta’s secret ice-ship for themselves.

So why leave it there, and not raise it to be conserved and displayed? The short and sweet answer is that there is not much of the project left. Time has taken its toll, and the organic activity of the lake water over decades has contributed to the material breakdown of the remnant wooden framework. Any move to bring it up would be monumentally expensive, and what is left of Project Habbakuk is not that visually impressive. The story lives on through history though, and scientists around the world still periodically test the suitability of pykrete for a building material. And if you ever find yourself in the position to travel to Alberta again, a mere 85-foot dive into the waters of Lake Patricia will lead you to the wreck’s underwater commemorative plaque, installed in 1988. Soon, this will be all that’s left of the strange history of Alberta’s best-known underwater wreck.


CBC Digital Archives. “Churchill, Roosevelt hold war conference in Quebec City”. CBC Radio News Special. Web. September 1, 2020. <https://www.cbc.ca/archives/entry/churchill-roosevelt-hold-war-conference-in-quebec-city&gt;

Chapman, Kit. “Pykrete”. Royal Society of Chemistry. Web. September 3, 2020. <https://www.chemistryworld.com/podcasts/pykrete/3007891.article >

Collins, Paul. “The Floating Island”. Cabinet Magazine. Web. September 3, 2020. <http://cabinetmagazine.org/issues/7/collins.php&gt;

Danchev, Alex and Todman, Daniel (eds). War Diaries 1939-1945 of Field Marshal Lord Alanbrooke. Phoenix Press, 2001. Print.

Gripper Products. “What happens when you shoot Pykrete?”. Grippy and Cormo. Web. September 3, 2020. <http://www.simegen.com/writers/lois/pykrete.htm&gt;

Maly, Tim. “How to Make an Indestructible Snow Fort – With Pykrete”. Wired. Web. September 3, 2020. <https://www.wired.com/2013/01/pykrete-snow-fort/&gt;

Perutz, Max F. I Wish I’d Made You Angry Earlier: Essays of Science, Scientists and Humanity. Oxford University Press. Print.

Prisco, Jacopo. “Project Habbakuk: Britain’s secret attempt to build an ice warship”. CNN. Web. August 30, 2020. <https://www.cnn.com/style/article/project-habbakuk-ice-aircraft-carrier/index.html&gt;

Royal Naval Museum Library. “The Habbakuk Project”. The National Museum of the Royal Navy Information Sheets. Web. September 3, 2020. <http://www.royalnavalmuseum.org/info_sheets_Habbakkuk.html&gt;

Swann, Brenda and Aprahamian, Francis. J.D. Bernal: A Life in Science and Politics. Verso, 1999. Print.

2 thoughts on “A giant aircraft carrier made of ice? A giant aircraft carrier made of ice.

  • Good Morning

    I just finished reading the Sara Bohuch story on Project Habbakuk and was wondering if I missed the credit for our photos used in the article. We send out many photos for this topic so I might have missed it, but I don’t remember authorizing these photos for the author.


    Karen Byers

    Archives Clerk

    Jasper-Yellowhead Museum & Archives

    Box 42, Jasper, T0E 1E0


    Open 9-3 by appointment on

    Tuesday, Wednesday, Friday & Sunday

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