There's a limit to how many ships an empire can field, which is represented by your fleet supply. Each faction begins with 100 fleet supply points, which is the base amount any race can manage without additional research. Every ship drains some of your available points, with frigates requiring the least and titans the most. Once you‘ve maxed out your available fleet points, you won‘t be able to field any additional vessels. When you mouse over your fleet supply at the top of the gameplay window, an InfoCard will appear listing your total points in use and how they’re distributed across your ships.
In addition to fleet supply, capital ships and titans require special commanders before they can be constructed. Each player starts the game with the ability to field one capital ship, which should be used wisely. In order to construct additional capital ships, players must research advanced training techniques. The number of available capital ship crews is displayed next to your fleet supply at the top of the main gameplay screen. By mousing over this figure, you can see where your commanders are deployed.