Excerpts from Books and Wikipedia
"The earliest references to the shipboard use of heavy artillery comes not from China but from Europe. Jean Froissart's chronicle of the Hundred Years War, written about 1400, mentions that some Spanish vessels about fifty years earlier carried 'everything necessary for their defence' such as 'crossbows, iron cannon, and culverins' (a culverin was a gun able to fire a smaller ball for a longer distance, and in due course such armament became standard." [Cambridge Illustrated History of Warfare, p. 120]