Project Habakkuk

Project Habakkuk or Habbakuk (spelling varies) was a plan by the British during the Second World War to construct an aircraft carrier out of pykrete, a mixture of wood pulp and ice, for use against German U-boats in the mid-Atlantic, which were beyond the flight range of land-based planes at that time.

Geoffrey Pyke was an old friend of J. D. Bernal and had been recommended to Lord Louis Mountbatten, Chief of Combined Operations, by the cabinet minister Leopold Amery.

In early 1942 Pyke and Bernal called in Max Perutz to determine whether an icefloe large enough to withstand Atlantic conditions could be built up fast enough.

The project would have been abandoned if it had not been for the invention of pykrete, a mixture of water and woodpulp that when frozen was stronger than plain ice, was slower-melting and would not sink.

[2] Perutz proceeded to conduct experiments on the viability of pykrete and its optimum composition in a secret location underneath Smithfield Meat Market in the City of London.

[10] The decision was made to build a large-scale model at Jasper National Park in Canada to examine insulation and refrigeration techniques, and to see how pykrete would stand up to artillery and explosives.

The requirements for the vessel became more demanding: it had to have a range of 7,000 miles (11,000 km) and be able to withstand the largest waves recorded, and the Admiralty wanted it to be torpedo-proof, which meant that the hull had to be at least 40 ft (12 m) thick.

[12] Naval architects produced three alternative versions of Pyke's original concept, which were discussed at a meeting with the Chiefs of Staff in August 1943: Air Chief Marshal Portal asked about potential bomb damage to Habakkuk III, and Bernal suggested that a certain amount of deck covering might be ripped off, but could be repaired by some kind of flexible matting.

Bernal considered that no one could say whether the larger Habakkuk II was a practical proposition until a large-scale model could be completed and tested in Canada in the spring of 1944.

Steam turbogenerators were to supply 33,000 hp (25,000 kW) for 26 electric motors mounted in separate external nacelles (normal, internal ship engines would have generated too much heat for an ice craft).

Its armament would have included 40 dual-barrelled 4.5" DP (dual-purpose) turrets and numerous light anti-aircraft guns, and it would have housed an airstrip and up to 150 twin-engined bombers or fighters.

[2] According to some accounts, at the Quebec Conference in 1943 Lord Louis Mountbatten brought a block of pykrete along to demonstrate its potential to the admirals and generals who accompanied Winston Churchill and Franklin D. Roosevelt.

The small prototype built in 1944 on Patricia Lake near Jasper, Alberta, confirmed the researchers' forecast that the full-size vessel would cost more money and machinery than a whole fleet of conventional aircraft carriers.

It was officially concluded that "The large Habbakuk II made of pykrete has been found to be impractical because of the enormous production resources required and technical difficulties involved."

The use of ice had actually been falling out of favour before that, and other ideas for "floating islands" had been considered, such as welding Liberty Ships or landing craft together (Project TENTACLE).

"[21] The Habakkuk design received criticism, notably from Sir Charles F. Goodeve, Assistant Controller of Research and Development for the Admiralty during the Second World War.

[22] In an article published after the war Goodeve pointed out the large amount of wood pulp that would be required was enough to affect paper production significantly.

In the 15 April 2009 episode of the U.S. TV show MythBusters Jamie Hyneman and Adam Savage built a small flat-bottomed boat dubbed Yesterday's News out of a modified version of pykrete, using whole sheets of wet newspaper instead of wood pulp.

They successfully piloted the boat in Alaskan waters at a speed of 25 miles per hour (40 km/h), but it began to leak through the melting pykrete in 20 minutes.

A rough hull using 5,000 kilograms (11,000 lb) of hemp fibre pykrete was frozen in a coldstore, then launched in Portsmouth Harbour for a planned trip across the Solent to Cowes.

Conceptual design of Project Habakkuk aircraft carrier with 600-metre (1,969 ft) runway
A block of pykrete