You can command more than one ship at once, provided that the ships under your command have an available Captain role, working communications, and crews which consent to your command by majority. Each ship for which you are the captain takes their turns on the same round of combat. You can choose which order the ships act in. Additionally, on your turn, you can use your action to take an action provided for you by the Captain role for each ship under your command.
You can command a number of ships equal to your proficiency bonus, up to a maximum of your Charisma modifier (minimum 2).