Odd history for the day

War History Online has an article about a wacky idea from World War Two:

At the end of 1941, the Battle of the Atlantic was in full swing and the Germans were sinking thousands of tons of Allied ships every month. Desperate to close the mid-Atlantic gap, an undefended area beyond the reach of land-based Coastal Command antisubmarine aircraft, the British proposed an unsinkable aircraft carrier made of pykrete, a mix of wood and ice, codenamed Habbakuk.
The idea came to Geoffrey Pyke, then working at Combined Operations Headquarters. 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 one percent of the energy needed to make an equivalent mass of steel. He proposed that an iceberg, natural or artificial, be leveled to provide a runway and hollowed out to shelter aircraft.
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 wood pulp that, when frozen, was stronger than plain ice, was slower-melting and would not sink.
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, and his tests showed that a pykrete ship would slowly sag unless it was cooled. 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.
A scale model was created in Canada in 1943, and naval architects and engineers continued to work on the project during the summer of 1943. The requirements for the vessel became more demanding: it had to have a range of seven thousand 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 forty feet thick.
Then the  Fleet Air Arm decided that heavy bombers should be able to take off from it, which meant that the deck had to be two thousand feet 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 a hundred feet high was never solved.
The final design of Habbakuk II gave the bergship a displacement of two million tons. Steam turbogenerators were to supply 33,000 hp  for two dozen electric motors mounted in separate external housing (internal ship engines would have generated too much heat for an ice craft). Its armament would have included forty dual-barreled 4.5″ turrets and numerous light guns, and it would have housed an airstrip and up to 150 twin-engined bombers or fighters.

The final meeting took place in December of 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.”
Engineers evaluated the viability of Habbakuk and concluded: “The 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.”

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