Military History blog

Project Habakkuk – Allied ice-aircraft carrier

During World War II, the Allies sought ways to effectively protect their supply convoys. Supply ships sailed across the Atlantic and were constantly attacked by German warships. Thinking mainly to reduce the threat of U-boats, and given the low supply of steel, British Prime Minister Winston Churchill agreed to the (not so crazy) idea from scientist Geoffrey Pyke’a to build a new type of aircraft. It wasn’t  built from steel, but instead ice.

The project was given the code name “Habbakuk” (Pyke’s  typo), which referred to the biblical Book of Habakkuk, 1:5:

“Look at the nations and watch— and be utterly amazed. For I am going to do something in your days that you would not believe, even if you were told.”

Habakkuk – Dominic Harman’s illustration
Source – by artist’s permission

On paper, the advantages of such an aircraft carrier seemed to be undeniable. The ship was to be made mostly of ice, and ice was something the Allies had in abundance. A possible torpedo hit wouldn’t entail any serious damage – in fact such a breach could be repaired on the spot, even during battle. The cost of creating such a giant was supposed to be small. This was due to the thought that forming lumps of ice would take 1% of the energy it took to construct something  from steel of similar weight. Unfortunately, soon after it was noted that ice can easily crack under the influence of strokes. Due to this, the design was temporarily abandoned.

It would have been probably been abandoned forever, if not for the invention of new material in 1943, named Pykrete (after Pyke). It is a mixture of sawdust and water; which can be formed into any shape and has a strength comparable to concrete. Pykrete fit perfectly to the concept of building “Habakkuk”, so the work on the project started with redoubled force. The creation of the giant aircraft carrier would be undertaken by teams in Canada, the UK and the USA.

A giant aircraft carrier made of ice

In the same year in the Canadian province of Alberta on Lake Patricia, engineers built a test model of the ship in a scale of 1:50; which is about the size of approx. 18 mx 9 m. The engineers were mostly depended on the creation of an effective cooling system which was meant to maintain the freezing material even when hot. During the test the ship managed to keep frozen all summer.

Ballistic tests have shown that the model made of of Pykrete was extremely resistant to the impact of torpedoes as well. The researchers were confident that given the huge dimensions of a real aircraft, the German navy in practice would not be able to destroy the ship by means of missiles and torpedoes launched from U-boats and surface ships. In any case, Germany would need very large quantities to critically threaten the aircraft carrier.

Unfortunately, the engineers quickly realized how incredibly expensive it would be to undertake building the Habakkuk. Additionally, the cooling system could turn out to be in-effective. For this reason experts decided to discontinue the project and sink  the existing prototype. Indirectly, the decision was also influenced by the fact that Portugal had opened its airports to the Allies in the Azores where the planes were able to start to protect supply convoys. In addition, Great Britain and the United States increased the number of escort carriers, which included the protective umbrella of the North Atlantic.

The brave plan of Allied engineers did not live up to reality and the great ice colossus was never made. The sunk prototype Habakkuk rests today on the bottom of Lake Patricia.


Source Royal Navy Museum Documentary movies

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