pixel_player68037793 Hello and welcome to the players forum! You answered your question already. You have only one slot available and you want to add a 2-slot ship => not possible. You need to put another 1-slot ship in dry dock, then you can add the 2-slot ship. Do not mix up dry dock with museum. When you put a ship in your museum you will never be able to use it again, so be carefull and think twice before doing so, especially with ships that have high sailor count, you will need them for explorations of the map once in a while. When you put a ship in dry dock you will always be able to switch it with another ship and thereby put it back into your active fleet. The No shown at your Main Dock is not the No of ships you can add but the No of ship slots you have available.