Waterborne can be fun.
[@ClocktowerEchos] Given the ship-nation idea I feel your inspiration could be Gargantia.
[img]http://vignette1.wikia.nocookie.net/suisei-no-gargantia/images/c/c1/Gargantia_fleet_2.PNG/revision/latest?cb=20140906011723[/img]
If you aren't, I think you can take a lot of ideas from that setting.
Well, save for the giant mechs and Galactic Alliance bits.