It isn't dome yet.. but it is basically the warlords version into BtS, but with new stuff.
So far.
In Battleships:
Trireme->Galleass->War Galleon->Ship of the Line->Ironclad Battleship->Dreadnought->Battleship
In Cruisers:
Frigate->Ironclad Cruiser->Armoured (WWI) Cruiser->WWII Cruiser-> Guided Missile Cruiser
In Light ships:
Early Destroyer->Destroyer-> Some modern one
Anti Sub Corvette
Torpedo Boat->PT Boat (Which reminds me, I found a nice free model of a PT boat, just need to get it skinned)
In Submarines: Submarine-> Attack Submarine, Missile Submarine
In Carriers: WWII Carrier-> Nuclear Carrier
Also, I am hoping to add a earlier marine unit that can fight on land, starts with amphibious, and can also be carried on certain warships (As a SPECIALUNIT_MARINE) and can bombard other ships (Just a little though)
Buildings:
Small Shipyard
Large Shipyard
National Shipyard (National Wonder)
Trafalgar Square (Or Admiralty/Navy Board)(World Wonder)
Retired (Museum) Ship
Training Ship (the last two can only be built with ships, aka the Military Academy)
Naval Academy (adds Naval Academy Branch to every city) (National Wonder)*
Naval Academy Branch (Can only be acquired by building the Naval Academy)*
I also want to try to get a new Great Person, the Great Admiral. Works like a great general, but is for only ships.
*With the Navy academy, I wanted the effect to be spread through out the country as the officers of that academy would be spread out to all new ships, not just the ones built in the same city.
So the Naval Academy branch gives +2 xp to every naval unit built.