Pykrete is a frozen mixture of sawdust and water, which is amazingly impervious to melting. In the waning days of WW II, British inventor Geoffrey Pyke proposed it as a material for building huge battleships which would withstand state-of-the-art firepower. It was rendered unnecessary by the end of the war, and the invention of nukes, which made such monster ships a liability (imagine floating, city-sized masses of fallout).
I was telling a co-worked about this recently, and he wondered why nothing else (that we knew of) was ever made with Pykete – say, cheap non-battle ships?
Thoughts appreciated.