|The Reader's Digest Book of Strange Stories, Amazing Facts. Montreal: The Reader's Digest Association (Canada) Ltd., 1975
K-boats were among several ideas explored by the British admiralty to deal with the U-boat threat in the First World War. (Other ultimately unsuccessful ideas included sinking barrels of fruit salts and then blowing them up to create enough effervescence to bring U-boats to the surface, or training sea lions to locate subs by their propeller noise.) K-boats were steam-powered vessels 330 feet long and heavier than the navy's biggest destroyers at the time. Diving involved shutting off the steam, dousing the boilers, lowering the two funnels and shutting nine watertight hatches, a process which took almost 5 minutes (compared to 90 seconds for a well-executed crash drive on a U-boat). The K-boat's length and weight made it difficult to trim and steer, leading to many collisions and a death toll of 270 (which almost included the future King George VI) before the concept was abandoned.