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There is more than one way to skin a cat, and certainly more than one way to build a fleet in HOI4. So, say it with me, our mantra!


But it’s water stuff, so we’ll say ‘fleet’ instead of ‘division’.

When the naval modifications for Man the Guns were finally released I could see the brilliant potential that new system married into the existing game. But for someone picking up HOI4 and NOT having MTG? I would advise against it. I’ll discuss the MTG content 99% of the time. If you buy one DLC, make it Man the Guns.

Within the guide, there is a lot of “ThEoRy CrAfTiNg” because... it has to be. So, plan your endgame. Then you can determine how long, how much and what type of Navy you’ll build.

In that feeling I guess I’ll be this skinny weird dude to your Thanos. *snap*



As far as credentials and why should you listen to any of this? I've banked more than 9000 hours playing HOI4. I love this game a lot. I've tried a lot of different YouTubers, Redditor, and other online ideas. Some are great, others are not as effective, especially after several years of content changes, patch releases, DLC updates, multi vs single-player settings and more. So let me close on this:

I’m an unorthodox player. I try to find ways to push advantage towards my single-player game style. This may not feel comfortable with you. That’s okay. Not everyone plays HOI4 the same, and we’re all better for it. I think I have a couple of pearls in here for you to take away, but seriously – adapt to your own play style and current game. Some results may shock you so try new things out. This is a guide for you to step off from. The pier to your own navy, if you will.

-OWC


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..
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Just so we’re speaking the same language.


aka Boom Squads!

The navy screen is F2 to access by default.

Let’s highlight the types of ship hulls in Hearts of Iron 4, then talk about the actual building of a fleet, composition, admiral upgrades and more.

• SS Submarine – cheap, slow, limited loadout options
  
  
• SS Cruiser Submarine – cheap, unique to a few countries, slow, special loadout options.
  
  
• DD Destroyer – light, fast, cheap. (can construct avg 8-12/year)
  
  
• CL Light Cruiser – Most versatile, Moderate to expensive cost, reliable and durable Moderate to Fast speeds. (can construct avg 2-4/year)
  
  
• CA Heavy Cruiser / Coastal Defense Ship – can be expensive, slow to Moderate speeds, Medium to heavy firepower
  
  
• BC Battle Cruiser – Moderate in nearly all categories. heavy firepower
  
  
• BB Battleship – Moderate to unreasonable costs, slow to moderate speed, heavy firepower, heavy armor
  
  
• CV Converted Carrier – Moderate to fast speed, relies on its parent class of Battleship or Cruiser hull for engine upgrades, cheap, weak, requires an escort.
  
  
• CV Carrier 36+ - can be cheap to moderate, reliable, requires an escort.
  
  
• Transport or Convoy – Required for transporting ‘goods’ such as reinforcements for divisions, equipment, and production resources across water zones within the game.

15+ knots is slow.

27+ knots is moderate.

35+ knots is fast.

Naval Yards are actually quite cheap to construct at 6400 production vs MILs 7200 and CIVs 10800. Their material needs, however, are quite high, more in a sec. If you plan to build a navy you really do need to take time to invest in these early due to the long build time of some capital ships, or creating vast numbers for a fleet.

I’m not going to bore you with any other math except this ONE bit. But you don’t even need to memorize it. Or even actively use it. You just need to be aware of it, how it works, and what the actions involved are.

Capital Ships can use up to 5 yards of production at a time, Screens and Subs use up to 10 yards, and transports can have a capacity of 15 yards working. A single Naval Yard outputs 2.5 production per day.

So!


You can mix in modifiers such as resource availability, dockyard output from construction tech, or focus bonuses, etc.

But lucky you! The game built all that in and tells you the date of completion, so, yay!



As an idea of time: A single dockyard can output about 900 production per year. The starting 1936 Battleship Italy gets, the Littorio Class, costs 11,487 production, so about 2 years of full speed construction with its bonuses.

It should be obvious, but worth mentioning, some countries will simply have a harder time putting a navy in the water than others. Ireland hasn’t got the same amount of naval zones as Sweden, and neither has the available resources, trading power or coastline as the United States.

Regardless of the nation though, the navy you construct in most cases will take years to create, not weeks like an army can.

So plan to have your ‘Grand Fleet’ hit the waves sometime around 1940-41 if you start early. Closer to 1942 if you’re building new capital ships, and 1943 for the more modern classes. There are exceptions.

Construction Tip: Build the max 3 refineries in a landlocked state, then fill in the same state with CIVs or MILs!Double bonus! Refineries give rubber for airplanes!

Most countries come with templates for a hull already, or there are national focuses that help get a small staring amount (usually 25 points) of naval experience. This is not much but, thankfully, you don’t need much to start designing ships. You will need a lot more if you plan to create a big navy… especially if it’s from scratch! Mao, I’m looking at you.

Once you have a boat (not convoys), set your ship to exercise and set the repair priority to auto detach. This will keep your ships in the water training and essentially mining for XP for as long as possible. Anyone that needs to repair will detach, repair, and return to training exercises.

Just don't forget it's on!

Check your Air and Naval Designers as well as Military Staff, for technology and stat upgrades available within your war cabinet. This could help you in several ways such as stacking bonuses together for submarine detection or carrier sortie efficiency.


Commanders that offer speed bonuses to your fleet will make you able to engage and disengage combat actions better. Some countries can really pile up advantages here and make for excellent battle groups. As always in HOI4: Speed Kills.


A single Admiral can lead 10 unique groups, so pile lots under one great admiral, even if it’s not his ‘specialty’. Such as an Air Commander operating a patrol squad of Destroyers. There are also static bonuses to leader experience gain, so make sure you look over your Admirals' abilities closely. Try to avoid Admirals that carry penalties to Anti Air, Speed, or Experience Gain and look for the better minor traits such as Gentlemanly, Craven. Two you need to look for are Career Officer (+10% XP gain! Horee sheet!) and Bold (+10% Speed).

When a ship is badly damaged in combat it typically disengages, if possible. So any critical hit, big or small, that doesn’t sink it outright will send that enemy boat running. While other boats are still reloading I like to have a second tube filled and firing.
Torpedo strength upgrades with tech, cooldown speeds don’t often get reduced. Take advantage of that. Use Lancer for surface torpedoes such as from a Destroyer, and Silent Hunter for submarines.

Fly Swatter, Fleet Protector, and Seawolf traits are good ones to focus on first and work for nearly any type of fleet. When applying upgrades, I typically move towards Concealment Experts and Loading Drill Masters for the far-reaching groups like Patrols. For the air controllers, I typically upgrade the fighters. Air Superiority at sea means nearly any tin can with a torpedo can make a ‘safe’ attack run on the enemy capital ships.

Finally, and important, is that Admiral upgrades do not have an indicator to say an upgrade is available. You’ll need to manually check them from time to time to see if they’ve earned one.

Ireland leases ‘Submarine I’ plans from Germany to work as convoy raiders in the Atlantic. Meanwhile, they are working to secure future techs through spies and research.

Many Bothans will be slaughtered in your pursuit of a spy-stolen-blueprint-navy, so use it as a bonus, not a crutch.





La Resistance brings in the ability to first infiltrate, then steal blueprints from enemy navies, armies, and air forces. These are essentially tech upgrades and are chosen more or less randomly from what’s still available in the research pool, and what has been researched by the target of the mission. You can’t suggest the spies try for “Super Heavy Battleship hull plans” in a mission, but if the enemy has them, there is a chance they may be acquired during the mission.

However, spies can add a significant advantage to your navy by gaining those tech upgrades you otherwise wouldn’t receive, so don’t ignore the possibilities they bring.



You need to have a high level of friendship, preferably even in the same faction, to gain enough favour to purchase licenses. This can be done via the diplomacy screen but be aware that the more gap between your existing tech and theirs, the less likely they are to give plans over to you. Even if allied.

Most licenses are cheap costing 1 CIV to maintain but a few are more expensive at 5 CIVs to maintain the blueprints. The ship you’re getting should really be something that you can’t build yourself, it isn’t worth the time to research, or it is needed strongly enough for creating an effective navy.

An example would be:

Guangxi Clique being at war with both America and Japan, GXC could NEVER create a navy if they didn’t first select the focus giving naval XP before the war started. They become locked out of the needed 25 XP to create a first ship design.

Leasing a Destroyer plan, say, from the Soviets, could get them building cheap convoy escorts, training them, and earning XP to make other homegrown designs later.

It’s a lengthy example and most times I don’t think you’ll need to lease a naval design. Cruiser Subs and Torpedo Cruisers are the exceptions. If you can afford it, you should lease and build these craft.

So you have a big pool of XP and now you want to spend it on some stuff! I can dig it.

Economics Tip: Never pay full price when you can pay half instead.

In my opinion, you shouldn’t purchase an upgrade that has a time reduction penalty still locked. Train the 50 XP for things like Depth Charges and Hull Armor upgrades. Or store up the 100 XP for Doctrine upgrades. I don’t usually fill out an entire naval doctrine tree, but typically one or two branches.

What doctrine should you use? I posted this earlier on Reddit and it still holds quite well for the La Resistance content update.

1 carrier + 1 capital ship = 😃

1 capital ship + 4 screens = 😃

8 screens = 😃

For example:
4 carrier + 4 Heavy Weapon + 32 screens = a Carrier group.

A patrol group of sub hunting destroyers? 8 screens.

Subs do great (I find) in groups of 8, and 12. But could be as big as 20 and 30.
Mostly depending on your output capacity.

*fist pump*

You have two spheres of thought to use here:

Fill It and Kill It -or- Strip It and Ship It.

Both are great, both have ups and downs.


These are meant to be built, deployed and used until destroyed. Quality without retrofit is the idea.

A single Destroyer with 3 ASW slots is a fantastic sub hunter when combined with sonar tracking and Radar. However, it will cost more production per boat, you’ll produce less each year vs a stripped-down version of the same thing, and you’ll typically need the tech available at the time of design or be forced to upgrade after. This can mean you're adding months or years to apply an upgrade to an already years-long project. Such as changing out a Battleship engine, or refitting 20 Destroyers with a new rank of radar.


The ships are built with one or two key components and otherwise use trimmed down equipment to save cost and time in production. By focusing on those key components and sending the ship off as soon as possible you can also quickly build numbers to gain supremacy over your enemy. Now, it’s not that the boats aren’t ‘good enough’ because they aren’t loaded to the teeth, in fact, in many ways they are superior to the Fill It and Kill It concept.

Submarine minelayers can be made slightly cheaper if you use lower engine upgrades or a smaller hull for example. And you can pump those out like hotdogs at a ballpark.


Not all ship redesigns are good ideas. You’ll need to check the cost in the bottom right corner of the naval designer screen to see if this is going to be a good item for refitting old ships or a waste of time and production.

Expensive items like armor, engines, and weapons can take a long time to change out and often are just better off spending a bit more time and producing an entirely new ship instead of refitting an old one. A good refit idea could be: adding or upgrading radar to a carrier, adding a minesweeper to an empty Destroyer slot, or changing torpedoes to mines on a Submarine.

Poor refit ideas are modifying a 2 rank increase or more in engines, ie, going from a rank 1 to a rank 3 or 4 engine or adding multiple new elements such as Antiair, Secondary, or Primary Batteries.

All designs and changes to existing plans will usually cost between 2 and 5 XP per slot. So upgrading a ship isn’t hard, nor too expensive. *chef kiss*

Originally posted by Admiral David Glasgow Farragut:

“Damn the torpedoes, Full speed ahead!”

The sign of membership in the Club.


Heavy Cruiser, Battleship, Super Heavy Battleship, Battle Cruiser, Coastal Defense Ship

These guys are the stuff of naval nightmares and sea-salty wet dreams. The pummeling they offer is only matched by air power. As always, there is a catch. The more stuff you cram on it the boat, the slower it goes. And gargantuan, overstuffed boats may as well appear to be islands to an airplane. There is a balance to find here.

The choice of a Capital Ship boils down to the 4 seashells.

Speed, Fuel, Construction Materials, and Screens.

You mean… you don’t know about the 4 seashells??




Because shelling. From a ship. At sea. Seashell.

Anyway. *dry cough*

Balancing those ideas will generally give you the answer to which Capital Ship will be the right one to build.

If you haven’t got many screens or you’ll need time to produce more, you may want to go for a longer build-time hull. A Battleship or Super Heavy could be a strong option here. Building 10 Destroyers will take a couple of years even if you have 10 yards dedicated to it. So, why not take advantage of that opportunity to produce a more robust vessel?

If you don’t have a ton of production time or available construction resources look to Battle Cruisers over Battleships. A heavily armored Battle Cruiser is quite fast and can hold a fair armament. Even the Royal Navy chose the more modern Battle Cruiser as its Pride of the Fleet. Although it was sunk…

¯\_(ツ)_/¯

So why use a Super Heavy Battleship at all? Well, flatly, they are hard to kill. They take a pounding better than the Energizer Bunny’s drum. They usually outlive most encounters and they often astonish me how well they can ‘pull one out of the fire’ and bring a win against some crazy odds. They make for a fantastic Pride of the Fleet because of this.

And regular plain ol’ Battleships, where do they fit in? A great place exists between speed and armor, and that’s where the Battleship floats. If you have the 4 seashells locked up, there is no reason you cannot produce Battleships.

They do not offer Heavy Weapon armaments but have instead a compliment that features Medium Weapons. These can still act as a Capital Ship in every way, and if well complimented can become a fearsome foe at sea.

Make no mistake though, a Heavy Cruiser is not the same as the other Heavy Weapon ships. Even Coastal Defense Ships. This is due to the restriction against Heavy Weapon mounts on Heavy Cruisers, but they’re pretty cheap on gas and materials compared to its larger counterparts.

Originally posted by Alexander Graham Bell:

"Neither the Army nor the Navy is of any protection, or very little protection, against aerial raids."

Never ever ever ever ever EVER let a Carrier go out without a heavy escort, sometimes several.

This is the one ship that just shouldn’t be wandering alone or even under-protected. The investment and the payoff are well worth the cost of protection so before you spam a carrier fleet, make sure it’s got support. The last thing you want is your shiny new 60-plane ubercarrier to slide into the drink because you got laid out by a pair of Light Cruisers on patrol.

Mmm Agility.

In nearly every country exists a Naval Aviation Design Company. It helps with research speed and some minor upgrades for naval-based airplanes. He is worth the purchase prior to doing the tech research for aircraft. Only a handful of countries start with naval airplanes to produce at the outset so you’ll likely have to research the tech.

If you plan to build a carrier group in your game, I strongly advise you to consolidate all aircraft production lines to naval air variants and forego land-based aircraft entirely.

i.e. Use carrier CAS vs ground CAS. They’ll benefit from the naval air designer also.

A local, or allied source of rubber is strongly advised, so you may need to build a couple of refineries. Remember to take the rubber upgrades when possible to limit the number of penalties you’ll face to the construction of your carrier aircraft. Building refineries can even bring you CIVs in rubber trade!

Destroyers and Light Cruisers are known as screening vessels or ‘Screens’ for short. They act as the icing on the layer cake of a fleet. It’s the first thing you see and the first thing to get attacked.

A real mess can be made of your naval layer cake if you don’t have sufficient screens. And ask yourself, how would Paul Hollywood feel about your stodgy Navy bake without icing? He’d say this:




" ... " ~Paul Hollywood

But numerically, how many should you have?

If they are doing a job such as a patrol, escort, or mine operation groups of 8 Screens could be used. You could bring it down to 4 screens if you include a capital ship such as a Coastal Defense, Battleship, or Heavy Cruiser.

Cam, you say, if I need 4 ‘screens’, and both a Destroyer and Cruiser are 'screens', then is a Destroyer equal to a Cruiser? Can't I just build the cheap Destroyers?

No, but yes! Now you're getting it! (heh, HOI4 whatcanisay) Some Cruisers are lightly equipped, others are heavily armed. The same can be true with Destroyers. Depending on the explicit details of your loadout there may be a reason to have one over the other. Pound for pound, Cruisers are better in the long run, given a hard choice to make ONE only.

A compliment of both can build a very strong surface fleet and every measure should be taken to build both. Especially if constructing capital ships! I like using 3 Destroyers to 1 Cruiser (but it’s usually loaded out).

Historically, Submarines were feared by many navies. I’ve played games where we ONLY used Submarines for naval combat. It was laughable. The French navy ripped us apart. The RAF stalked our every move. When we finally managed to get into a proper fight, our ability to go toe to toe with a Carrier fleet isn’t the stuff of legend because it’s not a favorable fight for the Submarines to begin with! I’m certain that you’ll find a way to create an undersea fleet of silent murder boats, but for this guide, the simple goods are what you’ll get.

There are 2 chassis frames for Submarine: The standard 4 tech unlocks and the sexiest of Submarines: the Cruiser Submarine. Oooo.



The extra armaments they receive are Fuel Tanks adding range, and Float Planes for increased scouting and a module slot for either a Snorkel or Radar. This means the boats can be a scout or a hunter to great effect with nearly unlimited range. It is truly a magnificent class and anyone who can build them, should. America, Japan, and Germany, I’m looking at you!

The Cruiser Sub is more or less the same as a rank 3 sub in layout, but not the engine or torpedo strength, yet. Later, they can be upgraded with new Submarine technology, so the hull never really goes out of date even by 1944, and by then the war at sea is typically already won or lost.

Look, these are thirsty beasts. If you can’t feed it, perhaps you shouldn’t own one. Fuel can be a problem with relentless training or operations and few countries can sustain it. Although, America and Russia can forge ahead without inhibition even when the tank reads ‘empty’. Some of the ‘light on Navy, heavy on oil’ nations can also do this relentless naval training to great effect. Romania and Canada for example and they earn a great pool of XP to use on tech and doctrine!

Britan fueling its Navy in Bengal ~ 1940 [Colourized].


Building refineries can help offset the costs of fuel for your navy. Early on refineries aren’t great, but as the technology progresses (and your navy grows!) it can be quite effective when the world is thirsty for any petrol. If fuel is a concern, don’t even think about Carrier groups without some serious upgrades or expansion goals to your oil and refining capacities.

The world has a few nice choke points in it such as around South Africa, the Cap Verde Plain, the straights around the Dutch Indies and others. Positions with air or radar support (or both!) are the most favorable to deploy in for zone control. Regions that have little access to air support, such as the Mid Atlantic Gap or the Central Pacific can be great spaces for Submarines to raid convoys safely away from land-based aircraft.

Keep to places that are friendly, close to home or that you can easily repair in without the risk of being bombed while in the harbor. For Germany, this could mean retreating the fleet back to occupied Poland for major repairs or finding harborage in an Italian or Japanese port.

Zone Spam, that is, just clicking every bloody zone for control, will typically only be effective if you have enough groups in your fleet to cover the specified areas. Using 2 Destroyers to cover the Atlantic isn’t really effective, clearly, but they will make a lazy looping patrol of all zones regardless.

You can access the missions for your fleet via the Naval Screen (F2) and assign zones of control from here as well. you may need to re-harbor your fleet and you can do this by right-clicking on a friendly harbor. Different missions will provide more or less superiority in a zone based on several factors such as the number of units, nearby radar stations and rank, as well as overlapping naval missions, which will all play a role in gaining or maintaining naval superiority.

Patrol: Chews gas. Great for screens. Use floatplanes, radar, or sonar equipped boats for better effectiveness. Land-based radar and scout airplanes help also. Combine speed and the 'Do not Engage' command for a stealthy type spotter group.

Strike Force: Saves gas! Keeps the big guns at harbor until the patrol has confirmation for a strike force to deploy. Speedy ships are great here. Don’t harbor strike groups too far away, they may not make the encounter in time. Multiple strike force squads can move to the same conflict and engage it simultaneously.

Convoy Raiding: Nearly any ship can be used for convoy raiding, but none are quite as effective as Submarines. This is their preferred theater of combat after all. The German U-boat wolf packs were deployed in groups of 8-20 and the same should be true here for subs on convoy raiding.

Convoy Escort: These ships need to be quick, durable, and able to hunt submarines. Destroyers and Light Cruisers pair well with Heavy Cruisers and even Battleships here. A group of 8 screens is a great start, but they can become busy if you’re moving a lot of equipment overseas or are involved in heavy resource trade.

Minelaying: If there was a second job for Submarines it’s as minelayers, or Egglayers as I call them during my streams. Using advanced minelayer tech creates a truly nightmarish scenario for your enemy. Mines slowdown enemy fleets, impede invasion progress and generally make life awful for your enemy.

Minesweeping: A couple of Destroyers with a single sweeper kit can be left to their own devices and do good work. Usually, you won’t need a gargantuan fleet here. Typically I use 5 Destroyers outfit with 1 minesweeper kit and that’s it. Just pick up to 3 zones and clean it up.

Bonus! The Admiral upgrade: Minelayer or Minesweeper, really top the mine operations off! *chef kiss again!*

Naval Invasion Support: Fleets will help convoys by escorting them on the way to an invasion and they will also help soften up the defenders when the invasion makes landfall. Big guns bring bonuses. Think of it like CAS at Sea!

Note: Use a Carrier that is NOT on a mission but deployed next to your invasion landing, that way it can offer air superiority and CAS support, but this needs to be manually deployed.



It is probably the only exploit I use if it is an exploit at all: To best make naval invasions happen at the outset of the war, is to deploy your fleet using the convoy raiding option, activate the marine invasion THEN declare war. The zones will be considered ‘controlled’ and your marines will immediately depart.

It doesn’t always work but most of the time it does. Other times selecting a different combination of missions will allow your invasion to proceed. So if you’re struggling with getting troops to bloody move, try changing their invasion support option to convoy raid or escort or any combination thereof. Failing that, you’ll have to do it the old fashioned way. Win control of the zones. But that’s fun too, so. Win-win.


These are probably one of the most important but overlooked options you’ll have on your deployment console. The bigger your fleet vs the enemy, the less you should fear them. Engaging at low or no risk can be great for patrols, minesweepers, and minelayers. Just find them and report the enemy position back, combat is someone else’s job.

If you’re trying to Little Mac your way to the top, staying alive is more important than engaging at all costs. But sometimes a fleet will not engage with an enemy because these settings are too low. Use care when selecting these options for your fleets. It can be the difference between success and failure at sea.

ASW Destroyer



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A 'Strip It and Ship It' build.



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The 'Quality Class' Cruiser



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With a 7000 km range. Who doesn't love long legs?!



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The "Flatticus" ~ A legend of the seas.



I'm not going to give you ALL the designs I use, there are lots. That's why I spent 5000 words explaining it. But you should get the idea based on everything discussed and pictured above.

I hope this helps new players find their sea legs, and maybe a few old sea dogs found a new bone they can chew on within their own games. The brilliance of the naval system in HOI4 is its sandbox depth. Get messy with it. It really has a lot to offer and is by far the single most pleasing addition to Hearts of Iron 4 franchise. For me, HOI4 Navy is like the ice cream buffet after pizza. You just don't care how much you hate yourself for attempting to eat it, you'll be happy you did and not care what you paid for it.

Hopefully, the idea of expanding this concept to the Air Theater has been kicked around the Paradox Studios. Adding elements such as Folding wing tech, wooden biplane airframes that upgrade to aluminum ones, the marriage of different engines to airframes (as was the story of the Supermarine Spitfire), or the idea of weight capacity for weapon load-outs restricting the size of the airframe used, or god forbid: bombers on a Carrier.


Dare to dream.

I feel it would behoove them to adopt this brilliant naval formula for the aircraft portion of the future game.

Thanks for reading and happy hunting.

Press the Scales button and assign Patrol or Raiding zones. Build Light Cruisers and max Engines, Reliability, and Armor.

Go buy: Man the Guns.

(i do not make a single red cent on your purchase - it is for your benefit you actually own this content if you own HOI4)
https://steamproxy.net/steamstore/app/815460/Expansion__Hearts_of_Iron_IV_Man_the_Guns/