This is just an informational post for anyone who might be interested. I did some research lately on the WW2 naval buildups and build plans for the various European naval powers. I mainly did so because I like to play naval underdog nations. I can't claim that everything is 100% correct, as there's a lot of information out there both true and false to dig through, and sometimes popular sources aren't always the correct ones. The original purpose of the thread was to focus on a few of the non-major naval nations, but it's since expanded to include every country that could build their own warships.
During my research I realized that Wikipedia's English Plan Z entry is complete and utter #%$@. The background info is mostly wrong, and the total ships of the Plan Z fleet are also wrong. Since some people like to play historical games and try builds that aren't always the best, I've compiled a few lists of what various nations built or planned to build and I've tried to use the most reliable sources I can find. That way, if you're interested in the subject you'll have a place to get accurate information from instead of bad info propagated throughout the internet to the extent that most people don't realize the information is wrong (Wikipedia's Plan Z article, I'm looking at you!). If anyone else wants to add new info or corrections, then please do so. Maybe this thread can turn into a go-to for those who are interested in trying out historical naval builds.
As a side note, if you want to try and convert the ships below to in-game units, then remember that the in-game DDs and SSs are groups of ships, not individual ones. PI has stated that DD units contain between 2-5 destroyers, and SS units contain between 5-10 subs. If you're using a mod with torpedo boats, then those units probably represent 10 ships.
Also, the detailed tech components that determine what model your ship is in-game can be found in the folder ../HOI3/units/models, or in ../HOI3/mod/mod_name/units/models if you're playing a mod that uses the mod folder. That folder contains all of the models for each country, so if you want to know what techs you need to research to build the exact Vittorio Veneto-class (also known as Littorio-class) battleships for Italy, you'd open up ITA - ships.txt and research what the battleship.4 entry says. You can find the model names in the file ../HOI3/localisation/models.csv. Note that there's a typo for the Italian battleship I just mentioned; it's listed as a level 3 BB in the localization file, but a level 4 BB in the model file (both start counting at 0, so those are not the same!). Sometimes there isn't a special model for a ship but there's a country-specific localization for a generic model. If you open the file ../HOI3/localisation/Models.csv and see something in there that isn't defined in the models folder, for example the Dutch Zeven Provinciën-class level 2 CL, then to build the right model you'll need to research all tech levels that match the class level. Using the Zeven Provinciën-class example, you'd need to research all level 2 light cruiser techs to build that model ship. The Scharnhorst is a level 4 ship, so to build the Dutch Design 1047 Battlecruiser you'd need to research all level 4 battlecruiser techs.
You'll also see the terms "commissioned" and "launched" thrown around the various entries. To clarify, there are 4 stages a ship goes through before it's combat ready. The first is the design stage, which is represented in-game by researching techs. The 2nd is the construction phase, also called "laid down", in which the ship's hull is built. The 2nd phase is represented by picking out which components you want for your ship before you hit the build button. At this point the various components of the ship could be adjusted in the design, so if it turned out that more armor was desired, it could be added here. The 3rd phase, launch, is when the hull is completed and the interior is being fitted. Aside from small guns like AA ones, at this point the ship's components couldn't be changed, and this phase is represented in-game when the ship is placed in the build queue. The last phase is commission, when the ship is completed and its crew trained and ready for combat. In-game, a ship is commissioned when you're able to place it onto the map.
Finally, when a ship was named varied by country. For example, the Germans and Soviets only named their ships when they were launched, the Italians named their ships when they were laid down, while the French named theirs when the ship was ordered, before any design work was done. That's why we don't know the names of the 2 German carriers that were to be built after the Graf Zeppelin and can only guess that the name of the 2nd German Graf Zeppelin-class carrier was to be the Peter Strasser, while we know the names of all 4 Alsace-class Battleships the French planned to build even though none of the ships were laid down and construction never started.
Fleet Compositions and Unit Descriptions
Currently finished navies. Click the country name(s) for a link to its post:
German Reich and Spanish State
Kingdom of the Netherlands and Kingdom of Italy
Union of Soviet Socialist Republics
Republic of Finland and The Republic of China
French Third Republic
Empire of Japan
United Kingdom of Great Britain and Northern Ireland
Kingdom of Norway and Kingdom of Denmark
Kingdom of Sweden
Polish Second Republic
Kingdom of Croats, Serbs, and Slovenes
United States of America
South American Navies compiled by Rancher. Click the country name for a link to its post:
I got most of my sources from this outside WW2 history forum: axishistory. Please note that the link is to an outside forum that isn't affiliated with Paradox Interactive, and Paradox is not responsible for any content on that forum. I prefer to get information from there as opposed to Wikipedia, because pretty much every post has a book or two cited as a source as well as Amazon links, whereas Wikipedia doesn't have that kind of oversight with its members.