Cog (ship)

The cog was the general trading vessel of the Middle Ages in north-west Europe. The first mention of a cog (kogge) occurs in a Dutch inventory in 948. Until overtaken in popularity in the 15th century by the hulk most of the deep-water carriage of freight off the Atlantic and Baltic coasts from Scandinavia to Spain and across to the British Isles was done in cogs.

They were a clinker-built, single-masted, single-sailed, square-rigged, wide-beamed vessels that were generous in their carrying capacity, had excellent stability, shallow draft, but were not exactly speedy. Whilst known as a trading vessel they were occasionally active in war – the Battle of Sluys during the Hundred Years War was fought on cogs – although that was more of a case of a land battle fought on ships than the normally perceived naval engagement.

William the Conqueror's invasion force force crossed to England in 1066 on a Norman variety of the cog, and this type influenced the development of the French nef (see Nao.)