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Last week's Dev Corner can be found here, but let's begin the next one!

Briefing: Hydrodynamics
Written by: Zwirbaum
Hello everyone!

Another week is upon us which means it is the time for another dev corner. Last week Thomas talked about what we are cooking with the Factions, while I will be talking about naval and naval-related changes. Even the most beautiful placeholder art will be gone eventually like tears in the rain. So strap in, and prepare for the deluge of the information that will be coming your way. Also, keep in mind that everything discussed here is in a relatively early stage, and as such is subject to change.
It is no secret that one of the most common sentiments across the Hearts of Iron IV player base is that the Navy seems to be rather hard to understand. Some elements are almost instantaneous in the effect (Supremacy), others take a long time (building the Navy) and some elements remain relatively hidden until the actual shooting starts (Supremacy Value of the Ships, Screening in Taskforces etc.). On top of that we are also having a fairly complex system of Naval Missions - where they work best when using them together, synergistically. However missions could be explained a bit better, and sometimes what is best to achieve your goal could be somewhat counter intuitive. (Giant Strike Force of Doom, sitting idle in the port somewhat projecting supremacy across the entire oceans without ever sailing out as one example). So how are we planning to address it?
Core Concept
Similarly to how last week we talked about high-level concepts for the Factions, I will try to do the same for the Naval Systems, but before that I will also list some of our goals that were the basis for what we are working on:

Updating and Reshaping Naval Gameplay, making it more strategic, giving you the opportunity for the counter-play if needed; a bit more predictable, and less ‘flip-floppy’
Updating Naval Missions so that they become more intuitive, with a much clearer purpose and use case
Encourage a more active use of fleets
Update and Communicate better to the Player some of the intricacies of the Naval Systems
Increasing the Importance of the Islands Control (in the Pacific) and Naval Logistics
Updating Carriers and address the interactions between land-based aircraft and naval taskforces

Update to Naval Gameplay
Naval Dominance
First of all, and the most important of the changes is that we are introducing the concept of Naval Dominance. Naval Dominance is a sort of umbrella term for a couple of things. Similar to how ships had Supremacy Value, now they have Naval Dominance Value, which will be displayed on the Ship Card.



Mutsu has 509 Naval Dominance Value. We are also changing the old calculation, that was based mostly on Production Cost and Manpower, to have more things affecting the calculation, like Speed and Range, so for those who want to build Fast Battleships, increased dominance value may be the reward…
Next, we will want to talk about Naval Dominance - which is our way of indicating naval control of sea zones. Each Sea Zone, depending on the terrain type, has a certain threshold of dominance points you need to have before you can claim you ‘control’ it. And if you are at war, then similarly to the older system, you are also taking into account enemies' Dominance Value and the ratios between you and them. Also the ratio needed for ‘control’ now has been adjusted to require 66% instead of 50%+1.
Having control, or as we call it now, establishing Naval Dominance in a Sea Zone, provides you with certain advantages and bonuses. For instance, as you can see in the screenshot below - potentially reducing the amount of convoys needed for Trade and Supplies by up to 25% if you have secured the entire shipping route.
There are other benefits that I will not fully reveal yet, but amongst other things, there will be something to help you secure islands and potential naval invasion targets.



In this example we can see that in order to claim ‘control’ over the Deep Oceans sea zone, you would need to accumulate at least 1000 points worth of Dominance, assuming nobody would contest you.
Dominance Gain



This tooltip shows the information about the current amount of dominance accumulated in this sea zone, how long it will take to establish its full value, things that impact it, like airbases located on the islands in the sea zone etc.
Dominance as opposed to the previous supremacy system now takes some time to establish, but it also doesn’t simply instantly disappear when ships engage in combat, or go to repair after a battle.
Naval Mission Updates
We will also be making the following changes to Naval Missions. We will divide current missions into 2 groups; Core Missions and Auxiliary Missions.
Core Missions - (PATROL, CONVOY RAIDING, CONVOY ESCORT, STRIKE FORCE)
Those missions are your primary way to interact with naval dominance. Each mission type will interact a bit differently. As it is right now, Patrol will be serving for Building Up Dominance, Convoy Raiding reducing Enemy Dominance, Convoy Escorts will provide a ‘protected’ value, which means enemy raiding won’t be able to reduce your dominance below that value, and Strike Force serving as a ‘Synergy Tool’ - and amplifying other missions. Hopefully this will provide a clear and relatively intuitive system on how to use the Naval Missions.
Auxiliary Missions - (NAVAL EXERCISE, MINELAYING, MINESWEEPING, NAVAL INVASION SUPPORT)
Those missions do not interact directly with naval dominance, however, they do benefit from it, like for example, being able to minelay or minesweep faster and more efficiently when operating within a region where you have established control and have naval dominance.
Naval Home Bases, Range & Supply



This Dutch Fleet has set the port in Batavia to be their Home Base.
We are reintroducing the Home Base system for the Fleets. Each Fleet needs to have a Home Base. Any Naval Base that you have access to (Your own, Subject or Faction Members, or if you have secured Docking Rights) can be selected as a Home Base. So the question is; what does the Home Base do?
Naval Range
One of the changes that we are doing is that the ship's range is now projected from the Home Base instead of all Naval Bases.






As you can see depending on where Home Base is located, the range, and access to do the Naval Missions is quite different. A fleet with Königsberg set as Home Base does not have the range to do the missions in Norwegian Sea or Western Approaches Sea Zone.
Naval Supply
Previously, naval units would always draw the supplies from the Naval Bases closest to where the taskforces were operating, now - they will be drawing the supply from their selected Home Base.



This fleet has a Home Base set in Honolulu - and is operating in the Micronesian Gap. Despite the port in Johnston Atoll being closer it draws the supply from Hawaii Naval Base Supply.
State Building Limit - Islands
In Götterdämmerung we introduced terrain-based limits for province-based buildings like Forts and Coastal Forts, so that you couldn’t build the Maginot Line everywhere. In a similar spirit, we will be introducing state-based building limits for the buildings. In this case we are now focusing on putting limits on the various Island categories, so that not every single tiniest of islands can have an airbase capable of storing and launching for missions 2000 planes every day. Right now those caps are based on the Island state categories (Tiny Island, Small Island, Large Island), and upon one concept we will talk about in the future.



Marcus Island can now have at most a level two airbase and level three naval base. Those limits as all the numbers, stats and values are of course subject to change. Also there is totally nothing hidden under that Hearts of Iron IV logo.
Short Comment
Initially when I started writing this section, I was going to write how I envision things mentioned so far will change the naval gameplay, and how X will impact Y, however I think I am more interested in hearing what you, my dear readers, are thinking and your opinion on what you have read today.
Naval Invasions
We are doing some touch-ups to the naval invasions as well. In the current live version of the game, there is a global naval invasion capacity set by your technologies, doctrines and other modifiers, and then depending on how many divisions you assigned to the invasion, it would take a certain amount of time to plan that naval invasion. This system unfortunately had one issue, that in order to be ‘optimal’, it encouraged to spam 1-division naval invasions, as that technically allowed you to have a massive naval invasion planned just within a few days, at the small cost of carpal tunnel syndrome.
In the new system, there will be, depending on your technologies, doctrines etc. a certain amount of naval invasions you can plan at the same time, each being able to have a certain amount of divisions, and no matter what, always taking a specific amount of time to plan.
Also, for a country that hasn’t researched even the basic Transport technology, there will still be a possibility to launch a very limited naval invasion under the new system.
Appeal to my Lizard Brain
And last but not least, I’m going to tell you about one more thing - and that is that we are adding visual representation of control over the seas, visible on default map mode, which during a conflict should represent a gradual shift of control over the zones, giving the feeling of ‘naval frontlines’. Also this can serve as a kind of warning, that when your coastline sea zones start displaying your potential enemy colours.



This is the current prototype of showing on the default map mode who has naval dominance. In this case Japan has the most dominance, and nobody is effectively contesting it, thus Japanese colors are displayed on the map.
Wrapping Up
So, to wrap things up, this is just a number of things we are doing for the Naval. I have not touched upon anything Carrier related, new equipment or new tools yet, or any UX/UI updates. I will return in due time to provide you with more information on all the things that are not-dry, in the meantime - here is a teaser of a thing that we may talk about in the future, with this beautiful placeholder art done by myself.



Who will guess what this is?
This is my first dev corner, so I can only hope my writing is not too stiff. In time I hope it will get better.
Anyways, thanks for reading and until next time, farewell!
/Zwirbaum


Also, we have a survey for you to fill out when/if you have time regarding Naval Gameplay. Just keep in mind that this Steam thread is for your feedback about the Developer Corner. If you have feedback about this specific survey we welcome your thoughts in a separate forum post, or in the HOI Discord!



Click the Image above or this text here to fill out the survey