The designs are saved untill you delete them, but they wont show up agin in another game untill you have all the techs you need to build them. If you realy like a "design" you can build it with only the hull and "extras" and it will show up everytime you unlock that hull. Then you can upgrade it to what ever techs you have and need for the game you are playing at the time. But save it as somthing differant when your done upgradeing it or you will overwrite the "template" ship.
