Project Habakkuk or Habbakuk was a plan by the British during the Second World War to
construct an aircraft carrier out of pykrete for use against German U-boats in the mid-Atlantic,
which were beyond the flight range of land-based planes at that time. The idea came from Geoffrey
Pyke, who worked for Combined Operations Headquarters.
History Initial concept
Geoffrey Pyke was an old friend of J.D. Bernal and had been recommended to Lord Mountbatten,
Chief of Combined Operations, by the Cabinet minister Leopold Amery. Pyke worked at Combined
Operations Headquarters alongside Bernal and was regarded as a genius by Mountbatten.
Pyke conceived the idea of Habbakuk while he was in the United States organising the
production of M29 Weasels for Project Plough, a scheme to assemble an elite unit for winter
operations in Norway, Romania and the Italian Alps. He had been considering the problem
of how to protect seaborne landings and Atlantic convoys out of reach of aircraft cover. The
problem was that steel and aluminium were in short supply, and were required for other
purposes. Pyke realized that the answer was ice, which could be manufactured for only
1 per cent of the energy needed to make an equivalent mass of steel. He proposed that
an iceberg, natural or artificial, be levelled to provide a runway and hollowed out to shelter
aircraft. From New York Pyke sent the proposal via diplomatic
bag to COHQ, with a label forbidding anyone apart from Mountbatten from opening the package.
Mountbatten in turn passed Pyke's proposal on to Churchill, who was enthusiastic about
it. Pyke was not the first to suggest a floating
mid-ocean stopping point for aircraft, nor even the first to suggest that such a floating
island could be made of ice. A German scientist, Dr Gerke von Waldenburg, had proposed the
idea and carried out some preliminary experiments on Lake Zurich in 1930. The idea was a recurring
one: in 1940 an idea for an ice island was circulated around the Admiralty, but was treated
as a joke by officers, including Nevil Shute, who circulated a memorandum that gathered
ever more caustic comments. The document had to be retrieved just before it reached the
First Sea Lord's inbox. Code name and spelling
The project's code name seems to have been consistentlyspelled Habbakuk in official documents
at the time. This may in fact have been Pyke's own error, as at least one early document
apparently written by him spells it that way. The name is a reference to the project's ambitious
goal: "... be utterly amazed, for I am going to do something in your days that you would
not believe, even if you were told." David Lampe, in his book, Pyke, the Unknown
Genius, states that the name was derived from Voltaire's Candide and was misspelled by his
Canadian secretary. However, the word does not actually appear in that text, so this
is probably inaccurate. Pykrete
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. Perutz pointed out
that natural icebergs have too small a surface above water for an airstrip, and are prone
to suddenly rolling over. 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. It has been suggested that Pyke
was inspired by Inuit sleds reinforced with moss. This is probably apocryphal, as the
material was originally described in a paper by Mark and Hohenstein in Brooklyn.
Pykrete could be machined like wood and cast into shapes like metal, and when immersed
in water formed an insulating shell of wet wood pulp on its surface that protected its
interior from further melting. However, Perutz found a problem: ice flows slowly, in what
is known as plastic flow, and his tests showed that a pykrete ship would slowly sag unless
it was cooled to −16 °C. To accomplish this the ship's surface would have to be protected
by insulation, and it would need a refrigeration plant and a complicated system of ducts.
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. The research
took place in a refrigerated meat locker behind a protective screen of frozen animal carcasses.
Scale model 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. Large ice blocks were constructed
at Lake Louise, Alberta, and a small prototype was constructed at Patricia Lake, Alberta,
measuring only 60 by 30 feet, weighing 1,000 tons and kept frozen by a one-horsepower motor.
The work was done by conscientious objectors who did alternative service of various kinds
instead of military service. They were never told what they were building. Bernal informed
COHQ that the Canadians were building a 1,000-ton model, and that it was expected to take eight
men fourteen days to build it. The Chief of Combined Operations responded that Churchill
had invited the Chiefs of Staff Committee to arrange for an order to be placed for one
complete ship at once, with the highest priority, and that further ships were to be ordered
immediately if it appeared that the scheme was certain of success.
The Canadians were confident about constructing a vessel for 1944. The necessary materials
were available to them in the form of 300,000 tons of wood pulp, 25,000 tons of fibreboard
insulation, 35,000 tons of timber and 10,000 tons of steel. The cost was estimated at £700,000.
Meanwhile Perutz had determined via his experiments at Smithfield Market that the optimum structural
properties were given by a mixture of 14 per cent wood pulp and 86 per cent water. He wrote
to Pyke in early April 1943 and pointed out that if certain tests were not completed in
May, there would be no chance of delivering a completed ship in 1944.
By May the problem of plastic flow had become serious and it was obvious that more steel
reinforcement would be needed, as well as a more effective insulating skin around the
vessel's hull. This caused the cost estimate to increase to £2.5 million. In addition,
the Canadians had decided that it was impractical to attempt the project "this coming season".
Bernal and Pyke were forced to conclude that no Habbakuk vessel would be ready in 1944.
Pyke was excluded from the planning for Habbakuk in an effort to secure American participation,
a decision that Bernal supported. Pyke's earlier disagreements with American personnel on Project
Plough, which had caused his removal from that project, were the main factor in this
decision. Naval architects and engineers continued to
work on Habbakuk with Bernal and Perutz during the summer of 1943. The requirements for the
vessel became more demanding: it had to have a range of 7,000 miles 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 thick. The Fleet Air Arm decided that heavy bombers
should be able to take off from it, which meant that the deck had to be 2,000 ft long.
Steering also raised problems; it was initially projected that the ship would be steered by
varying the speed of the motors on either side, but the Royal Navy decided that a rudder
was essential. However, the problem of mounting and controlling a rudder over 100 ft high
was never solved. Variants
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:
Habbakuk I would have been made of wood. Habbakuk II was closest to the COHQ model
and would have been a very large, slow, self-propelled vessel made of pykrete with steel reinforcement.
Habbakuk III was a smaller, faster version of Habbakuk II.
Air Chief Marshal Portal asked about potential bomb damage to Habbakuk 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. It would be more difficult to deal with bomb holes in the centre
portion, though the roof over the aircraft hangars would be made proof against 1,000 kg
bombs. Bernal considered that no one could say whether the larger Habbakuk II was a practical
proposition until a large-scale model could be completed and tested in Canada in the spring
of 1944. He had no doubts about the suitability of pykrete as a material, but said that constructional
and navigational difficulties remained to be overcome.
The final design of Habbakuk II gave the bergship a displacement of 2.2 million tons. Steam
turbogenerators were to supply 33,000 hp for 26 electric motors mounted in separate
external nacelles. Its armament would have included 40 dual-barrelled 4.5" DP turrets
and numerous light anti-aircraft guns, and it would have housed an airstrip and up to
150 twin-engined bombers or fighters. Shooting incident
According to some accounts, at the Quebec Conference in 1943 Lord Mountbatten brought
a block of pykrete along to demonstrate its potential to the admirals and generals who
accompanied Winston Churchill and Franklin D. Roosevelt. Mountbatten entered the project
meeting with two blocks and placed them on the ground. One was a normal ice block and
the other was pykrete. He then drew his service pistol and shot at the first block. It shattered
and splintered. Next he fired at the pykrete to give an idea of the resistance of that
kind of ice to projectiles. The bullet ricocheted off the block, grazing the trouser leg of
Admiral Ernest King, and ended up in the wall. Sir Alan Brooke's diaries support this account,
telling how Mountbatten brought two blocks, one of ice and one of pykrete. After first
shooting at the ice, with a warning to beware of splinters, Mountbatten said "I shall fire
at the block on the right to show you the difference". Brooke reported that "the bullet
rebounded out of the block and buzzed round our legs like an angry bee".
Max Perutz gave an account of a similar incident in his book I Wish I Made You Angry Earlier.
A demonstration of pykrete was given at Combined Operations Headquarters by a naval officer,
Lieutenant Commander Douglas Grant, who was provided by Perutz with rods of ice and pykrete
packed with dry ice in thermos flasks and large blocks of ice and pykrete. Grant demonstrated
the comparative strength of ice and pykrete by firing bullets into both blocks: the ice
shattered, but the bullet rebounded from the pykrete and hit the Chief of the Imperial
Staff in the shoulder. Brooke was unhurt. End of project
Later in 1943 Habbakuk began to lose priority. Mountbatten listed several reasons:
Demand for steel for other purposes was too great.
Permission had been received from Portugal to use airfields in the Azores, which facilitated
the hunting of U-boats in the Atlantic The introduction of long-range fuel tanks
allowed British-based aircraft extra patrol time over the Atlantic
The numbers of escort carriers were being increased.
In addition, Mountbatten himself withdrew from the project.
The final meeting of the Habbakuk [sic] board took place in December 1943. 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. It took three hot summers to completely melt the prototype constructed in Canada.
Perutz wrote that he stayed in Washington D.C. while U.S. Navy engineers evaluated the
viability of Habbakuk. He concluded: "The U.S. Navy finally decided that Habakkuk was
a false prophet. One reason was [that] the enormous amount of steel needed for the refrigeration
plant that was to freeze the pykrete was greater than that needed to build the entire carrier
of steel, but the crucial argument was that the rapidly increasing range of land-based
aircraft rendered floating islands unnecessary." Criticism
The Habakkuk design received criticism, notably from Sir Charles Goodeve, Assistant Controller
of Research and Development for the Admiralty during the Second World War. In an article
published after the war Goodeve pointed out the large amount of wood pulp that would be
required, enough to affect paper production significantly. He also claimed that each ship
would require 40,000 tons of cork insulation, thousands of miles of steel tubing for brine
circulation and four power stations, but that for all those resources Habakkuk would be
capable of travelling at only six knots of speed. His article also contained extensive
derisive comments about the properties of ice as used for ship construction.
Recent recreations In the 15 April 2009 episode of the U.S. TV
show Mythbusters Jamie Hyneman and Adam Savage built a small boat out of a modified version
of pykrete, using newspaper instead of wood pulp. They successfully piloted the boat in
Alaskan waters at a speed of 25 miles per hour and inferred that it is possible to build
a boat out of pykrete. They also concluded that pykrete lived up to its purported properties
of being bullet-proof, stronger than ice and taking longer to melt than ice. However, they
expressed doubt that an aircraft carrier made of pykrete could have survived for long. The
conclusion was "Plausible, but ludicrous." In September 2010 the BBC programme Bang Goes
The Theory also attempted to recreate a pykrete boat. A hull using 5,000 kg of hemp fibre
pykrete was frozen in a coldstore, then launched in Portsmouth Harbour for a planned trip across
the Solent to Cowes. The hull immediately started to leak because of the holes that
had been cut in its rear to mount an outboard motor.
See also Mobile offshore base
Notes
References
Further reading Perutz, M. F.. "A Description of the Iceberg
Aircraft Carrier and the Bearing of the Mechanical Properties of Frozen Wood Pulp upon Some Problems
of Glacier Flow". The Journal of Glaciology 1: 95–104.
Cross, L D. Code Name Habbakuk: A Secret Ship Made of Ice. British Columbia, Canada: Heritage
House Publishing Co Ltd. ISBN 978-1-927051-47-4. External links
Goodeve, CF, Bergship, GoodeveCA . Some notes on the article by Perutz referenced above.
Habbakuk, Royal Naval Museum . Strange Story of H.M.S. Habbakuk, The War
Illustrated, April 12, 1946 . "Modern", Venture across America and Canada,
U-Haul .