And their bold keels the trackless ocean plough’d;
— Luís Vaz de Camões, Lusiads (Bk 1, trans Burton)
Portuguese sea power becomes more pronounced with the nau, a prototype version of the carrack. Borrowing the sturdy hull of the cog and the lateen sail used by the Saracens, the Nau is a hybrid of sailing traditions from the Atlantic and the Mediterranean, all meant to come togethet to form a new type of vessel capable of long-distance voyages and some greater mobility. Thus, the Nau, although smaller than a normal carrack, combines the rate of fire and the armour of a carrack with the hull of a lantern galley, lending it the same manoeuvreability.
Despite this, the Nau still has the same enemies as most heavy warships. Massed firepower by galleys (and less likely, galleases) will easily overwhelm them, despite their good speed and attack. In the face of fire ships and Byzantine cheirosuiphon vessels, expect the nau to be wholly useless.
- Fire Hazard — Fire ships are most powerful against any form of heavy ship, so keep these as far away from your Naus at all costs.
The renowned workhorse of mediaeval empires, the cog, was a variant of roundship unique to Northern Europe. Taller and sturdier than the Norse-styled longships of old, the cog not only could carry more goods than the former, but it also surpassed them in combat performance, with its higher freeboard and fo'c'sles, which granted the advantage of a higher position for the men on board. The success of the Hanseatic league, and later the Victual Brothers (a guild which later turned to piracy in the Baltic) were all due to the use of the cog in battle. Ships of similar size and operation were also used in the Mediterranean, where their main use continued to be transport of goods by sea.
Originally an indigenous version of the roundship, the nau (derived from the old Portuguese word for ship) was in fact a combination of the Baltic cog with the lateen sail of the Mediterranean, with hybrid rigging. The benefits of this were manifold: not only did the new variant have the strength and room of a common roundship, but it also had the benefit of flexibility thanks to a lateen sail that could be adjusted to ride out against the wind like a galley (albeit its large size meant it could not be easily rowed if becalmed). With its manoeuvreability and size, the most famous role the nau ever played was in the arduous trade journeys made to India. For many decades afterwards, the term "nau" eventually meant India-bound ships, even if those were by then carracks or galleons which were even larger than the nau had been.