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 it would stand up to artillery and explosives. At Lake Louise, Alberta, large ice blocks were constructed, and a small prototype was constructed at Patricia Lake, Alberta, measuring only 60 by 30 feet (18 by 9 m), weighing in at 1,000 tons and kept frozen by a one-horsepower motor.[8] 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.[citation needed] Bernal informed COHQ that the Canadians were building a 1,000 ton model, and that it was expected to take 8 men 14 days to build it. The Chief of Combined Operations (CCO) 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, with further ships to be ordered immediately if it appeared 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.[9]
Meanwhile, Perutz had determined via his experiments at Smithfield Market that the optimum structural properties were given by a mixture of 14% wood pulp and 86% 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", and Bernal and Pyke were forced to conclude that no Habbakuk vessel would be ready in 1944.[9]
Pyke was excluded from the planning for Habbakuk in an effort to secure American participation, a decision which Bernal supported. Pyke's earlier disagreements with American personnel on Project Plough, which ultimately caused his removal from that project, were the main factor in this decision.[10]
In the early summer of 1943, naval architects and engineers continued to work on Habbakuk with Bernal and Perutz. 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, while the Admiralty wanted it to be torpedo-proof, which meant that the hull had to be at least 40 ft (12 m) 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 (610 m) long. Steering also raised problems; it was initially projected that the ship 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 (30 m) high was never solved.[9]
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) but I severely underestimated the amount of sawdust I'd need. FYI: you need a 
