Turtle ships had precedents in the fifteenth century but had disappeared from active service long before Yi's birth. The first wartime vessel was probably not conceived and built from nothing in the three weeks after Okpo. A more plausible interpretation is that Yi had studied the earlier design, prepared resources during his year in command, and perhaps arranged for panokseon hulls that could be converted quickly. The uncertainty itself reveals how innovation can depend on local initiative concealed from an obstructive central bureaucracy.
Notable Point · 2:06:20-2:13:39
Yi revived an old design through advance preparation
The turtle ship was a revival of an older Korean concept, and its rapid appearance suggests Yi prepared materials or convertible hulls before the war.