Project Habbakuk: A Ship Made of Ice

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A scientist named Geoffrey N. Pyke sold Winston Churchill on a plan to build a ship of ice in 1942. The project’s name, Habbakuk, came from a biblical reference that reflected the effort’s goal: “…be utterly amazed, for I am going to do something in your days that you would not believe, even if you were told” (Habakkuk 1:5). Unlike in the Bible, the ship’s name was spelled with two Bs and one K, most likely a spelling error repeated so often it became official. The ship would have been 2,000 feet long and 300 feet wide and weigh 2 million tons and include 40 dual-barreled gun turrets, as well as other anti-aircraft guns, and an airstrip accommodating up to 150 fighter planes or twin-engine bombers.
Britain had been getting clobbered by German ships and submarines and was seeking something from which to build a ship that could withstand torpedoes or at least take a drubbing without fatal damage. Because steel and aluminum were scarce, Allied scientists and engineers were prompted to come up with alternative materials and weapons.
Pyke chose ice because it was readily available: it could be made and it is buoyant, easy to repair, and durable. Furthermore, crews could repair it quickly with the right equipment, even during a battle.
Testing for the project revealed, however, that ice frozen into blocks for the hull could be broken easily with just a hammer. The project was temporarily abandoned as a result.
But later that year, a New York polytechnic firm added cellulose—sawdust, wood chips, and paper shreds—to water and froze it, producing a more promising base structure for such a ship. Not only was it stronger than ice, with just 4 percent of wood pulp added to the ice, the material was as strong as concrete, pound for pound. It also melted much more slowly than ice and had more buoyancy. It could also be cut like wood and milled into shapes like metal. The material was dubbed Pykrete, after Geoffrey Pyke.
One drawback to Pykrete was that recurring melting and refreezing would warp the ship. Tests showed that a Pykrete ship would eventually sag unless consistently cooled to around 3° Fahrenheit. To maintain this, the ship’s surface would have to be covered in insulation and it would need a refrigeration plant and duct system.
To experiment with insulation and refrigeration issues and determine the ship’s ability to withstand artillery shelling, eight conscientious objectors who did alternative service built a small-scale version of the Habakkuk in Canada’s Lake Patricia. It took them 14 days to build the 30-foot wide by 60-foot long ship weighing 1,000 tons. It was kept refrigerated with a one-horsepower engine. The shipbuilders were not told what they were building. It took three hot summers to completely melt the model.
Ballistic testing determined that a direct torpedo hit would cause about a 10-foot crater in the hull, insignificant given the size of the proposed ship.  Even if the ship was broken up, the Axis powers would have to invest incredible resources in a given area to do it, considering the aircraft on the ship. This would have weakened the enemy on other fronts during the attack. If the enemy failed, crews could easily make repairs. Therefore, the full-sized version seemed plausible and a bargain at $2.5 million (about $32 million today) for such a ship.
Another hurdle to the production of the real ship was the size of its rudder, which would have to be massive. Mounting the rudder so that it could resist attack was also a problem, as was controlling such a rudder. In addition, the amount of wood pulp needed would have impacted paper production. Even though the ship would need much less steel than other ships, the steel tubing needed for reinforcing the structure would have depleted reserves for conventional, proven warships. Furthermore, a huge amount of cork would also be required to insulate the ship. Finally, the ship’s top speed of just six to seven knots would be too slow, even though the main structure would be torpedo-proof. These problems, along with a significant increase in the range of aircraft available, made the need for the ship less important. The project ceased.
Pyke conjured many outlandish ideas during the war. Despite only some of his ideas having any merit to them, Chief of Combined Operations, Louis Mountbatten, kept Pyke around because the scientist’s stream of ideas was good for stimulating the other members of his staff to think more outside the box.
When World War I broke out, Pyke had stopped his university studies to become a war correspondent. He was sent to Berlin, using an American passport obtained from a U.S. sailor.
In October 1914, after just six days in Germany, Pyke was arrested. Left behind was an incriminating letter—written in English—on his desk. Guards told him, “Probably you’ll be shot in the morning.” While incarcerated, Pyke longed for books, writing materials, and, above all, company. At the rare exercise times, when no talking was allowed, he moved briskly around the yard, exchanging a few whispered words with the inmates he passed.
In January 1915, he was taken to another prison where he was able to mix with other prisoners. But after five days he was transferred to his third prison and five days later, he was taken to the internment camp at Ruhleben.
This is where one of his “crazy” ideas paid off.  Most of his fellow prisoners thought him nutty to attempt an escape because even if he could get out, he would either starve, be caught, or killed before getting out of Germany. He proved them all wrong. He meticulously studied all the escape attempts thus far by others and the reasons they failed. He then devised a plan, at which point he and Edward Falk, a fellow inmate, began a rigorous exercise routine to prepare for their journey.
Pyke had noticed a shed housing athletic equipment, which, while regularly checked by soldiers, was checked at a time of day, when, if the sun was out and it was the right time of year, a window in the shed would reflect the sunshine, preventing the soldiers on patrol from seeing properly. He and Falk hid in the shed and the guard could not see them.  After hiding, they left the camp at night with food they’d rationed. Following a harrowing journey, they made it to a border where they were caught but not by a German soldier. The soldier was Dutch; they were in The Netherlands. They had made it.
The eccentric Pyke committed suicide in 1948 by ingesting a bottle of sleeping pills. He left a note saying it was intentional.