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Pykrete - Experimental Ice Ships in the Rockies.

A Project Overtaken by Events


In early 1943, two American professors discovered that a very tough material was created from a frozen mixture of wood pulp and water. They called this material Pykrete in honour of Geoffrey Pyke, who had earlier proposed the construction of ships made of ice. This is the improbable but true story of a top secret WW2 project to undertake research into the use of ice in the construction of ships.

[Map courtesy of Google Map Data 2017.]

To reflect the unbelievable nature of the project, the codename Habakkuk was taken from the book of the same name in the Hebrew Bible; Behold ye among the heathen, and regard and wonder marvellously: for I will work a work in your days, which ye will not believe, though it be told to you.

In 1942, the Allies were already developing plans for the invasion of Europe, which included experimentation in the construction of large floating platforms to support the landings. In addition, the allies were suffering heavy merchant shipping losses from German U-boats, due, largely, to the limited range of patrolling aircraft and the resulting "mid Atlantic air gap." Churchill, therefore, welcomed the idea of building large ships made of ice, as explained to him by Lord Louis Mountbatten,

Mountbatten, Chief of the Combined Operations Command, worked alongside the Chiefs of Staff on all matters concerning offensive joint operations against the enemy. These operations involved the three services in small amphibious raids on the coasts of enemy occupied territory as well as major landings, which culminated in D Day. Mountbatten's remit also included the development of equipment and special craft for these offensive operations.

One of his scientific advisers, Geoffrey Pyke (photo opposite), suggested constructing "berg-ships" up to 4,000 feet long, 600 feet wide and 130 feet in depth, that could be made cheaply, in great numbers, from ice. The ships would be insulated and cooled and would be practically invulnerable to bombs and torpedoes. They could be used by aircraft to provide protection for shipping, particularly in the mid Atlantic and as a base for invasion. With Winston Churchill’s enthusiastic endorsement, the project got underway.

Lord Mountbatten had a block of Pykrete prepared by a Canadian engineering company and took it to the Quebec Conference in the fall of 1943. As it appeared that "Habakkuk" would run into supply, technical and financial problems ($100 million for the first ship), Mountbatten hoped the Americans might take over the project, if they could be convinced. What better way than to set up a live demonstration! The story goes that he took out his revolver and fired at a block of ordinary ice, which immediately shattered. He then fired at a similar block of Pykrete, which was so strong that the bullet ricocheted, narrowly missing Sir Charles Portal, Chief of the Air Staff!

The Trials

Studies commenced into the two paradoxical elements of ice – plastic flow and brittleness. One such study involved the creation of a structure, 60 feet long by 30 feet wide and 19.5 feet high. The top secret location for this experimental work was Patricia Lake, near Jasper in the Canadian Rocky Mountains.

[Photos opposite; work in progress on Patricia Lake, Jasper, Alberta, Canada. Circa 1943. Courtesy of the National Research Council of Canada.]

The structure comprised a wood frame with 3 inch x 6 inch studs and 3 inch x 8 inch floor joists. It was filled with ice cut from the lake, insulated and cooled by 3 Freon compressors driven by 10 hp electric motors. Cold air was distributed throughout the ice by a network of 6 inch galvanized-iron cooling pipes. This study was to identify problems in construction and to record the thermal behaviour of ice in the heat of summer. No Pykrete was used in these trials.

A concurrent experiment was undertaken in front of the Chateau Lake Louise, near Banff, Alberta. This project was to determine ways to reinforce large ice units. The work at Lake Louise indicated that a hull at least 35 feet thick would be needed to contain damage from bombs and torpedoes. However, by this time, the 'Battle of the Atlantic' was all but won and new conventional aircraft carrier construction was promising to further strengthen defences. With these changes in circumstances, the project was shelved.

The floating structure in Patricia Lake was abandoned at the end of August 1943 after removing all machinery. It was left to sink. In the 1970s, scuba divers discovered the remains, which were subsequently studied by the Archaeology Department of the University of Calgary.

In 1988, the Underwater Archaeological Society of Alberta marked the site with an underwater monument. The following year, with the assistance of the National Research Council and the National Parks branch, a plaque, commemorating these unusual wartime events, was erected on the shore of the lake.

Further Reading

There are around 300 books listed on our 'Combined Operations Books' page. They, or any other books you know about, can be purchased on-line from the Advanced Book Exchange (ABE). Their search banner link, on our 'Books' page, checks the shelves of thousands of book shops world-wide. Just type in, or copy and paste the title of your choice, or use the 'keyword' box for book suggestions. There's no obligation to buy, no registration and no passwords.

Elsewhere on this site - Geoffrey Pyke 1894 - 1948

Find out about the properties of Pykrete including photographs of blocks subjected to gunfire.

Imperial War Museum, Lambeth Walk, London - books available:-

The Past has Another Pattern memoirs by George W. Ball 1982 ISBN 0-393-01481-9

Pyke: the Unknown Genius David Lampe 1959 (no ISBN given?)

The Challenge of War: Scientific and Engineering Contributions to World War II  Guy Hartcup 1970 ISBN 0-7153-4789-6

"Scientists at War" Wilfred Eggleston 1950   (no ISBN given)

Canadian War Museum- books available:-

No Day Long Enough  George R. Lindsey. Canadian Institute of Strategic Studies 1997

I wish I'd made you angry earlier - Essays on Science and Scientists by Max Perutz. The essay that discusses the development of Pykrete is entitled 'Enemy Alien'. A fantastic read written by one of the greatest scientists ever. ISBN:0879696745.

Butter Side Up: Delights of Science by Magnus Pyke (ISBN: 0330253093 / 0-330-25309-3) This book was written by Geoffrey Pyke's first cousin and includes a chapter on Pykrete. Copies available on line through ABE Books mentioned above.


Researched and written by George H Pitt, Alberta, Canada.

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