I'm not at all sure that most nations had a permanent navy in 1492. England certainly didn't. Navies were generally created on an "ad hoc" basis by requisitioning merchant ships. I know that Venice operated a permanent navy, at that time entirely composed of galleys, which was used to protect the republic's vulnerable merchant galleys, which travelled in state-organised convoys to places as far afield as Tana and Kaffa on the Black Sea; Alexandria, Egypt; or Southampton, England, and Bruges in Flanders.