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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.

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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:

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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.

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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.

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  • 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
 
Would be interesting if flying boats/naval bombers on patrol could also increase number number of rescued sailors, if only for flavour.

Looking good! any chance to make it possible to recreate events like the sinking of the Blucher?
Harbour assaults is something I have dreamt of for a long time.
 
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It doesn't sound like much of a rescue effort was made to rescue survivors of the Scharnhorst. (anyone know why that was?)

Maybe having naval superiority should increase the proportion of rescued sailors.

Because it was night, and there was a threat to the vessels from enemy submarines which meant that the less risky option was to withdraw to protect the vessels (which are always more important afloat) over recovering enemy sailors and risk being sunk (and therefore not being afloat).
 
So 1500 tons displacement is a small ship (London treaty restriction on Destroyers)? Fletcher Class Destroyers were 2100 tons displacement. Destroyers were in the deep ocean throughout the war on escort duty of various sorts, even played a very key role in the battle of Leyte Gulf. I don't think destroyers should be penalized in any way in a deep ocean; at least not major sea powers such as UKN, IJN or USN. You could make a case for smaller nations lacking expertise, training or opportunity but the class itself is very deep ocean. Please do not restrict Destroyers, this is very unrealistic.

I nearly fell out of my chair in laughter when I read deep ocean is like plains on land. Ah, no its not even close. Have you ever been at sea? On a clear calm day at sea you can literally see for miles. On a clear day visibility will differ depending on sea conditions but seeing out 15,000 meters is not unheard of. On a tower 100 meters high, you can see 19,600 meters, that is where the curvature of the earth prevents you seeing further. (https://en.wikipedia.org/wiki/Horizon ) With special range finding binoculars (world war II technology) you can even get the distance to the object you are seeing, like another ship, down to the nearest 100 meters.

On land, even the flattest of prairies, you are lucky to see more than 1000 meters without some land feature getting in your way. There are also ravines to hide in, small hills and other terrain to hide your unit and equipment. At sea, there is nothing to hide you.

I really hope you are not using a land combat engine to simulate Naval warfare. The two are entirely different. As different as night is to day. Please tell me you have a separate naval combat engine and not relying on the same one you use for land combat? And air is another totally different simulator. Airplanes at sea respond differently than airplanes on land.
 
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Cheers for the DD Podcat, terrain-iriffic :D. It all looks pretty good to me - shallow seas in particular :). As others have mentioned, arctic waters were more brutal than shark-infested waters in terms of casualties, but appreciate numbers are WIP (and will be balanced for gameplay as well as boring historical plausibility cranks like me) :).

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.

Others have explained that cold weather wasn't just about wearing a thicker coat, but here's a pic to hopefully demonstrate how cold weather had an impact on fighting a ship. Arctic ice build up impacted on ship handling and operations and, if left unchecked, could even capsize a ship (although an admiral shouldn't need a special trait to work that one out :)). There were definitely better and worse ways of tackling the challenges of arctic oceans (or shallow oceans and fjords), and tactics varied for open water (Blue Oceans) vs 'narrow seas' (the rest).

Anyways, enough rambling - it's pic time - put a coat on :). Actually, two pics (I found another cool one that I thought might be interesting). The first is a person on the deck of a corvette on Arctic convoy duty, I've posted it before but it's about the best example of ice-build up in the arctic I have!

Cold in the arctic.jpg


The second is the Gneisenau in the Baltic in winter - not strictly arctic, but I thought the ice being shaken off her barrels during firing was cool :cool:.

Gneisenau gunnery exercises.jpg


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.

Mines could be laid in pretty deep water. The max laying depth of the British Mk XIV (the most-used British contact mine during the war, and the British laid more mines than anyone else) was 1.8km, and they laid a field between Scotland and Iceland. Japan and the US both had mines that could be laid out to 0.9km (US) and 1km (Japan) and Italy, Denmark and Sweden all had mines that could be laid to 1.5km. This won't cover all the ocean though, and there definitely depths at which mines tethered to the sea floor in one way or the other (the vast, vast majority of mines) weren't practical to be used.

In WW2, the Brits invented HFDF which was useful against surface U boat attacks at night, the invention of RADAR helped too. The Germans cleaned Americans clocks when they entered the war and were using seemingly Pre WW1 tactics (no convoys, no coastal black outs).

HF/DF was used to triangulate u-boat radio contacts prior to an attack, and was useful for both submerged and surface attacks, as analysis of the pattern and frequency of traffic gave escorts a pretty good idea what was coming. Radar was very good for surface attacks at night (or in mist/fog), as it meant poor visibility was no longer a good cover. US tactics at the start of the war weren't based on complete igorance (they wanted to have convoys, but they thought convoys without escorts would be worse than no convoys at all, so didn't implement them until they had enough escorts) - but they should have known better, and were advised as such by their more experienced Allies, and they made a number of 'unforced errors' (like the coastal blackouts).

Don’t waves get higher as the water gets shallower?

I'm not full-bottle on this, but while this is true for surfing/tsunamis as they hit shore, the mid-Atlantic gets some pretty brutal swells, and typhoons in the Pacific in the open ocean can be pretty nasty too. In my reading (which is far from exhaustive), the strong impression I get is that open ocean is worse for swell/sea state than coastal waters (in that larger swells tend to be out in the open sea).
 
@podcat - a couple of people have asked about this, but I'm going to also:

What do you mean about naval casualties? Will there be a different manpower funnel for Navies?

Can Admirals drown?
 
Will the Great Barrier Reef have any impact? While ships could fight off shore away from the reefs, any attempted amphibious landing could be brutal.
Will there be anything to coasts to affect amphibious landings and suitability? I'm not suggesting the 'banana' icon from HOI1, but differing amphibious assault penalties/attrition could be used.
 
I don't understand why light ships would get a penalty in deep water. From the perspective of a surface ship 1000m depth is the same as 3000m depth right?

Maybe they can't fight submarines as effextively? But that's already represented in the submarine boost.
 
I don't understand why light ships would get a penalty in deep water. From the perspective of a surface ship 1000m depth is the same as 3000m depth right?

Maybe they can't fight submarines as effextively? But that's already represented in the submarine boost.

Deeper swells in deeper seas made it more difficult for light ships to maintain speed relative to larger ones (this, for example, was the reason that in the late 19th century torpedo boats and torpedo boat destroyers were only really a threat in coastal waters, and it wasn't until larger destroyers came to be that they could practically be taken to sea, but higher sea states still limited the speed of the smaller ships more than the large ones). This can mean that in rougher weather, a 28kt battleship can travel faster than a destroyer whose top speed is 35kts.

I'm afraid I'm not the right person to ask about the details though - haven't come across anything that explains that 'straight up'. I imagine it's got a fair bit to do with the relationship between the hull size/weight, the depth of the swell and the location of the screws (ships pitching about such that their screws are out of the water will tend to slow down more :)).

As best I can recall, the only destroyers that were sunk (capsized/otherwise foundered) in heavy weather, were well away from the coast (in the Pacific in Typhoons, like the fourth fleet incident, or in the Mid-Atlantic).
 
Interesting, perhaps might give a reason to actually use fleets just composed of screen ships.
 
Im not sure if im pining for the fjords or not. I mean for example the Baltic Sea shouldn't be completely archipelago/fjords. I dont think it makes sense that the Norwegian one stretches so far to the sea also. I guess it's gameplay > realism. 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.
 
Im not sure if im pining for the fjords or not. I mean for example the Baltic Sea shouldn't be completely archipelago/fjords. I dont think it makes sense that the Norwegian one stretches so far to the sea also. I guess it's gameplay > realism. 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.

This is a reallistic tactic. Many countries used land based torpedoes, torpedoe boats, mines, monitors, coastal battleships and I guess patrol planes to keep enemy navies off their coast. A single torpedoe aimed carrefully can terribly dammage any ship even the biggest. That's why blockade were not that common in WW2. The UK had a navy big enough to just camp outside of any German ports, bomb it to dust, or wait so that their ship does not escape. But doing so would expose precious ship to surprise night attacks from torpedoe boats, or to be hit by coastal batteries with very strong guns (that would have a very good accuracy against static targets for sure).

It would be nice if man the game could represent this as well... it could show why amphibious assaults were not used that often, and why Overlord required so many men, ships, aircrafts, etc...
 
I don't see the logic behind light ships being bad in deep oceans. I would say that simply heavy ships don't have a penalty there, and heavy ships are inherently superior to light ships.

It's obvious you've never been to sea then. Small boats don't do well in the rough seas that are common in deeper waters. In calm waters, sure no problem, but wait until that ship with a 2 foot freeboard gets into a sea state of 3. All hell would break loose. Just look at the USS Wasmuth (DD-338), A Clemson class DD that was sunk because a storm caused two depth charges to explode.

Even larger ships could have a hard time while in storms on the high seas. A good example would be the USS Pittsburgh (CA-72) in this video. I'll grant you 100 foot waves and 70 kts winds arn't common, but a smaller ship would have floundered and sunk like the Edmund Fitzgerald on lake Superior
 
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That's because the background used for the (ocean) map tries to be realistic in terms of depth, and from a satellite's point of view the sea there becomes clearer because the continental plate is shallower. (Just like off the coast of Irland)

*flies away*

Uuh I think that's it. They should probably reduce this effect in this simplified map hahha so it is clearer
 
It's obvious you've never been to sea then. Small boats don't do well in the rough seas that are common in deeper waters. In calm waters, sure no problem, but wait until that ship with a 2 foot freeboard gets into a sea state of 3. All hell would break loose. Just look at the USS Wasmuth (DD-338), A Clemson class DD that was sunk because a storm caused two depth charges to explode.

Even larger ships could have a hard time while in storms on the high seas. A good example would be the USS Pittsburgh (CA-72) in this video. I'll grant you 100 foot waves and 70 kts winds arn't common, but a smaller ship would have floundered and sunk like the Edmund Fitzgerald on lake Superior

The navy ship my city used to have couldn't go into deep water, which was pots for search and rescue. Waves tipped it over, normal sea waves. It was a minesweeper though, which I think is smaller than a destroyer in-game though.
 
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.
Will this vary with ship design? For instance, will the game treat ~1000 ton destroyers like what Sweden had differently from the ~3000 ton destroyers that, as an example, France had. My understanding is that open Oceans were really rough on early torpedo boats, but the larger post-Fubuki designs – once the kinks were worked out – were pretty okay.

Similarly, if your nation is building Light Cruisers the same size as your heavy cruisers, are you still taking those Light Cruiser penalties?
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.
Are we likely to get any sort of warm water trait? My understanding is that Tropical waters had their own downsides.
 
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 ;)
When you watch hardcore history before work
 
So... If we talk about surviving chance mechanics on sinking, then it should be extra more surviving chance in archipelagos and shallows, also running aground chance may be added in a sea battle for big ships, especially for CVs. Another suggest, maybe you can also add disease mechanics for sea and land in war. The last suggest, you should add sinking chance due to storms for light ships.
 
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