• We have updated our Community Code of Conduct. Please read through the new rules for the forum that are an integral part of Paradox Interactive’s User Agreement.

HOI4 Dev Diary - Naval Terrain

Today we are going to talk about Naval Terrain and start talking about some of the core changes to the naval game.

We felt that we wanted to make where you fight more important, and where possible give advantages to people fighting in home waters. The sea in HOI4 has previously generally been either “ocean” or “ocean in range of enemy land based aircraft”, and otherwise mattered little. That’s about to change!

To do this we are introducing several terrain types for seas. These impact what ships work best there, how mines function as well as some other stuff. In total seas are divided into 4 types:
ocean.jpg

Regular Ocean has no special effects, so its similar to plains on land.

Screenshot_4.jpg

Fjords & Archipelagos come with some hefty penalties to big ships, but make it easier to hide (all numbers still quite work in progress btw!)

Screenshot_3.jpg

Deep Oceans on the other hand are not good for light ships. They are also not good place to mine due to their depth and vastness. Subs like this area (mid atlantic gap = bae) because it is also easier to hide here.

Screenshot_5.jpg

Shallow seas are a bit harder to maneuver well in, and not a great place for submarines.

There is also some possible modifiers on them:

Screenshot_6.jpg

Arctic Water is a general bad area to operate in, wearing your ships down and causing potential accidents. It also increases casualties if ships sink for any reason. This modifier works much like Extreme Cold on land so it depends on the time of year and temperature.

Screenshot_7.jpg

Some places in the world have quite a lot of sharks and there are a lot of stories of heavy casualties after the sinking of ships due to sharks. The USS Indianapolis is a famous example where due to several reasons, sharks among those, something like 75% of the crew were lost. It is honestly mostly a cool flavor thing though we wanted to have in ;)

Your performance in these are also affected by Admiral Traits. As we have shown a bit before your Admirals can now gain traits for different terrain types.

Screenshot_2.jpg

  • Cold Water Expert reduces the impact of arctic waters
  • Inshore Fighter gives combat bonuses and speed when operating in Fjords and Archipelagos
  • Blue Water Expert gives combat bonuses and speed when operating in deep oceans
  • Green Water Expert gives combat bonuses and speed when operating in shallow seas
You might have noticed some strange colors in the screenshots above. We are adding some more mapmodes, but it’s mostly all pink and full of coder art at the moment, so you are going to have to wait a bit more to see all those. I am pointing it out because I need to show the terrain mapmode a bit to more easily show off the naval terrain across the world
Screenshot_8.jpg


Around the Dutch East Indies several of the terrain types are visible (the colors on land in this mapmode are still in need of some tweaking btw). The brightest there is archipelagos with the other shades of blue being shallow seas and regular ocean and the darker areas is deep oceans.

This is what the Atlantic and Europe looks like:
Screenshot_9.jpg


Notice the deep ocean in the Atlantic and the fjords around scandinavia.


That’s it for this today, next week we are going to start going over some of the more core naval changes. Seeya then!

Rejected Titles:
  • Naval “terrain” is an oxymoron, like “Military Intelligence”
  • SHARKS
  • Fjords, or how to make Scandinavia relevant this DLC
  • Not from the creators of Sharknado, comes SharkBlizzard
  • Podcat read a book about how horrible it was being on a destroyer in the arctic
 
Check the alternative diary titles, in the "spoiler" section.

gg, USSR or Scandinavia dlc confirmed? I mean who else operated in arctic seas
Its either Nordic countries, or soviets with its White Sea's northern fleet.

Also, theoretically that can be both - Scandinavian focuses + USSR rework (winter war immersion)
 
(...)What could be done is to make quite narrow sea provonces near coast and have those be fjords for example, but I dont know would that make sense for the gameplay. On the other hand, it could allow something like "defend coastline" naval mission. That way a country with light ships only could try to hold up against countries with bigger ships and prevent them from making invasions and bomb coastline. Don't know if that is realistic tactic though.
Agree. And on a related note - if all coasts had a very narrow sea province along it, you could also simulate coastal forts firing at ships. So, the current forts would be able to not only make an amphibious invasion harder, but also have an effect on ships passing by along the coast, just like a minefield would have.
 
I'm really glad to see some terrain effects at sea. I absolutely can't wait for this to come out.
 
Can we have a shallow water deep mine field that only effects submarines? This tactic was used off the UK coast line to decent effect.
 
Last edited:
I mean, will there be special engagement rules for straits? Eg no ability to maneouvre for large ships, deadly mines, etc or something?
 
.....[snip].....]
Very nice, thank you.
I think that the sea types will work very well with the ship designer when it comes to actually defining what you need in your fleet(s).

Couple of questions/points:-
1) Are those modifiers for each type of zone permanent or season dependent? No one wants to drive a ship around the Magellan straits in winter etc, but summer.. different story. The North Sea, average visibility changes drastically during different seasons (I have seen figures stating that the year round average visibility is something like 2km, not sure of it's veracity though).
2) Mid atlantic gap - was very good for submarines.. but nothing to do with the actual 'water' itself, purely for it's remoteness. And... a lack of escorts that had the range/technology to actually adequately protect the convoys, finally, until escort carriers became 'common', no air cover - which is also why it is called 'the gap'.

__________________________
Smaller ships v's larger and sea state
For those who are not aware of the impact that heavy seas had on warship performance, an easy way to see it in practice is to took up the encounter between HMS Renown and the twins (Scharnhorst/Gneisenhau) during the Norwegian campaign.
Renown with DD's bumped into the pair in heavy weather and gave chase when the twins started to retreat (they didn't want combat against another capital ship). The DD's with Renown couldn't keep up in the weather and fell behind, Scharnhorst, IIRC, lost the use of her front 2 turrets due to flooding caused by her high speed, Renown had one of her anti-torpedo bulges start to detach itself from the hull also due to speed/weather (although design/fitting was also a component of this). If you come across pictures from this era, most warships sailing through any form of sea state, you will note that their turrets are turned to port or starboard, that is to reduce the amount of water entering the turrets through the gun ports.
Another example is if you drive a ship too fast through heavy seas, you risk actually buckling the ship frame itself. HMS Glorious in her BC form suffered from this and as a result all three of the 'funnies' (Glorious, Furious and Courageous) had their frames strengthened.
 
Agree. And on a related note - if all coasts had a very narrow sea province along it, you could also simulate coastal forts firing at ships. So, the current forts would be able to not only make an amphibious invasion harder, but also have an effect on ships passing by along the coast, just like a minefield would have.
That sounds like a very good idea. Then it would be possible to model the effect of narrow sea areas like Calais-Dover and Gibraltar much better. Not just like now completely open or closed. You could drive through, but take damage by coastal batteries, depending on day/night and weather.
 
If you're allowing minefields... What about the odd mine that loses its anchor,
A VERY slight chance of a ship 'accidentally' meeting up with one of these... but with catastrophic consequences.

I could imagine a Battleship in the middle of the Atlantic having a VERY bad day! :)
 
To what extent will weather and storms play a part?
We have weather on land eg rain / mud / snow / blizzard.

These effects should also play a part at sea. I mean there is a big difference between north atlantic mid-summer on a calm day and mid-atlantic in a mid-winter storm. Some sea regions experience particularly nasty weather. Artic convoy in a blizzard and your survival rates on sinking are not just 20% more, but 90% more. Eg. Convoy PQ17.
 
Can someone help me, what does it mean in real life to be a "cold water expert" for an admiral? How could an admiral mitigate the effects of the weather without just...leaving it? Maybe Paradox just wants a modifier for each thing, but I don't know of any way that an admiral, by using their own skill, could affect that.

Speaking as someone who has sailed in pretty arctic waters (I think we were a few degrees short of be being able to say actually arctic) there actually are lots of things a captain could do that would help.

I can see how these might not be obvious so here are some examples (non-exhaustive)
- re-arranging abandon ship procedures to minimise time spent in the water. Generall you attempt to make a 'dry' abandonment anyway but there are ways you can increase this and generall increase your odds of survival if your ship goes down. When we sailed into colder waters for example we moved our immersion suits (like wetsuits that keep you dry and warm) to more accessible locations and did extra lifeboat prep drills.

- Knowing which hatches and ventilation systems to batten down and when, admittedly not a complex thing but it helps.

- Adjusting watch rotas to minimise time spend above decks

- increasing vigilance around de-icing and generally dealing which risks brought by colder weather

- provisioning correctly

All of these things can help, and some of them are less obvious than they might seem - especially back then.

The deep-water mine penalty seems a bit light as well. I mean surely you can't chain a minefield in place on the bottom of the ocean without having to carry dozens of kilometres of chains with you.

Free-floating mines were a thing- although as the modifier indicates they were far from very effective.
 
1) Are those modifiers for each type of zone permanent or season dependent? No one wants to drive a ship around the Magellan straits in winter etc, but summer.. different story. The North Sea, average visibility changes drastically during different seasons (I have seen figures stating that the year round average visibility is something like 2km, not sure of it's veracity though).

Season dependant conditions sound very cool, perhaps as temporary modifiers like mud works now - I will say though that 2km average is WAY off. You can easily see vessels at 10x that on most days - and the season doesn't matter much except to make fog and rain more common - even in rain you can see much greater than 2km almost always. Of course in fog you can bearly see the other end of the ship.
 
What about storms like historical/plausible hurricanes, typhoons, and monsoons? That way players are more careful about where they park their fleets. It would also give penalties to naval invasions.
 
Good ideas, but nonsensical implementation.

If I'm reading this correctly it means that it will be harder for subs to hide near the British Isles than in the Mediterranean?

Paradox got this one ass backwards. That's not at all how sub concealment works. It's not really about how deep the water is but how translucent it is. Italian subs in the Mediterranean were easily spotted from the air by the British thanks to the clarity of the Mediterranean sea and the abundant sunshine.

In the North Atlantic, the sea is virtually opaque after a few meters down, which made it much easier for the U-boats to remain concealed.

Shouldn't sea terrain be on the province level not on the state level?

Is anyone else struggling to tell the shallow and normal oceans apart?

Is it just me, or is this... not well done at all? Why do destroyers have their movement halved in the deep ocean again? If anything, penalties like this should be weather based.

Deep and normal ocean should be nearly 0% chance for mines

No mine hitting bonus is shallow water and/or straits? Boo! I can't mine like just the Gibraltar? :(

I know these numbers are WiP but those debuffs to destroyers in deep sea are too harsh. I can see these numbers beeing reasonable when there is a storm but when its calm or just a bit windy they should be way lower.