NOTE: playing Vanilla Is it possible to upgrade naval units? If so, how? I usually don't start building a navy until later in the game; destroyers and battleships. In some earlier games, I ended up with fleets of ironclads- useless against later era ships. I focus my game on air superiority, and tanks. However, I got whooped by the Azteks in my last game because I could not get a transport (with escort) to their continent. I would like to learn more about naval strategy. For example, is there any cost-effective way to blockade? On regent level, how much navy do I need? How do units differ? Should I focus on battleships or pump out cheaper subs? I usually skip the frigates and galleons, and wait for transports and battleships. Am I being prudent, or wasting opportunity?