Navy Guide in Russian[//]. Translated by Vasko[//].

This guide will cover everything there is to know about navy, from gameplay basics to advanced ship designs! I'll start this guide with a very important quote:


This quote perfectly describes what the navy is is used for; cutting off enemy supply lines, and securing your own supply lines.

The army and air force have a bigger impact on the war than the navy. For this reason, 1936 ship designs are shown for most ships. Large ships also take long to complete, and you want them finished before WW2 starts. The only techs that are really good are Fire Control and Submarine Hulls; many other navy techs aren't worth the investment. You'll achieve more with planes at sea, so build planes, and don't build dockyards.

Let's get on with the guide!



Terminology

CA = Heavy Cruiser (Cruiser hull with heavy primary gun)
CL = Light Cruiser (Cruiser hull with light primary gun)
CV = Carrier (Carrier hull)
BB = Battleship (Heavy ship hull with battleship armor)
BC = Battlecruiser (Heavy ship hull with batllecruiser armor)
DD = Destroyer (Destroyer hull)
SHBB = Super Heavy Battleship (SH hull)
Screens = ships in the screening/'front' line

When you press F2, the naval interface will pop up. Although the interface might seem daunting at first, using your navy is actually easier than using your army as it doesn't require any babysitting when properly set up.

A quick overview:

• Each admiral can have up to 10 task forces under them.
  
• Each admiral has selected sea zones assigned to them.
  
• Each Taskforce performs their mission ALL those sea zones.

The task force missions.

• Naval Exercises: this trains your taskforce, leveling up your ships, which increases their damage; just like army training does. In addition, it will also grant a lot of navy XP. If you are low on fuel, try exercising submarines, as these use very little fuel.
  
• Patrol: Actively search the sea for enemy ships (spotting). Both surface ships and submarines can be spotted. Once you spotted the enemy, you can immediately fight them, or keep observing them from a distance, depending on engagement rules for that taskforce.
  
• Strike force: Your ships stay in the harbor, waiting until an enemy fleet is found. Then they will attack that fleet (or not, depending on engagement rules). This also passively projects naval superiority on sea zones; more on that later.
  
• Convoy Raiding: Attacks enemy convoys. Typically performed by submarines, but any ship can be used for this, even your strike fleet.
  
• Convoy Escort: Protects your convoys against enemy ships. Typically performed by Destroyers.
  
• Minelaying: Lays mines, giving you extra naval superiority, and increases the chance of enemy ships randomly sinking, and reduces enemy ship speed by up to 80% (!).
  
• Minesweeping: Removes mines, removing their effect.
  
• Naval Invasion Support: Escorts convoys carrying troops.
  
• Hold: Stand still in their current location. Provides Shore Bombardment, which debuffs enemy troops.

A battle between 2 large fleets ends up with 1 big winner, and 1 big loser. Once one side gains the upper hand, they will 'snowball' into destroying almost all enemy ships, typically immediately followed by another battle that cleans up the remains. You'll want to win this decisive battle at all costs.

Put your strike force on 'Always Engage', 'Split Off: Disabled' and 'Never Repair' (or Low Repair Priority) to prevent your ships from fleeing during this decisive battle; this setting also ensures your fleet chasing down the enemy fleet after beating them. Once you've won this decisive battle, you should change these settings back, to allow for repairs and Split Off. Try to actively watch the ongoing battle; manually retreat when you're losing!

The best doctrine for a big battles is 'Fleet in Being'; especially the last slot of this doctrine is very important (10% attack increase).

If you are playing as a major nation, you'll want to put all ships in the same task force (Deathstack). Your deathstack only needs to be comfortably larger than the enemy fleet; excess ships will not contribute that much and eat your fuel supply dry. Don't use submarines in this Deathstack, as these are very bad in big battles; once submarines reveal themselves, they will die to depth charges very quickly.

For optimal strike fleet composition, you'll need:

• 4 Carriers. Only build 4, the 5th one barely does any damage. Aircraft carriers are by far the most cost-efficient ship type.
  
• Battle line ships; (e.g. battleships). Build as many of these as possible.
  
• Screening ships: 6 per ship in the battle line. Ships that start in the battle line are: Heavy Cruisers and (Super Heavy) Battleships. Screening ships can be either destroyers (good at tanking, very cheap) or light cruisers (very good at dealing light attack damage, expensive).

You need a minimum of 1 battle line ship per carrier. (torpedo screening is not relevant when the battle line is already under torpedo attack; this line is also extremely vulnerable to torpedoes.)

There are 2 common strategies:
- Balanced fleet, with a strong battle line. This allows you to attack the enemy carriers early on.
- LA cruiser fleet, with a focus on LA cruisers. The strategy of such a fleet is to destroy the enemy screening line, then kill the rest using torpedoes.

Both strategies will work, but against A.I. the LA cruiser fleet is your best choice. Note that the 'LA cruiser strategy' is countered by a cheap destroyer fleet.

It is extremely important to protect your carriers. If your carriers get sunk, you will likely lose the battle. So you need to keep your own battle line alive, and sink the enemy's battle line, which allows your own battleships to start attacking the enemy carriers.

At the same time, your battle line is vulnerable to torpedoes. Torpedoes absolutely obliterate enemy battleships, but can only attack those once the the screening line has been destroyed. You need enough screening ships throughout the whole battle. My recommendation is 6 screens per Battleship, such that you have a buffer before you reach 3 screens per battleship threshold (else torpedoes will start to hit your battleships).

SHBBs will obliterate BBs, which means using SHBBs will win you the battle line combat. Then, the enemy carriers can be destroyed.

Aircraft carriers are the most cost-effective ship.
Even if you have a small starting navy, you'll want to have 4 of these! Armor isn't necessary, since these operate from the back. Anti-Air is good for shooting down enemy (carrier-based) naval bombers, and reducing damage taken from them. You don't need radar or fire control, as those stats are useless for the planes. You'll want to use only naval bombers on your carriers for maximum effect.


Put 2 factories on these carrier-based naval bombers, and you'll have enough to fill out the deck space of each of the 4 carriers by 1939.
If possible, build planes with torpedo 2 (1940 tech): these have ~4x the damage output!


If you are bound to the London Naval Treaty, you cannot build SHBBs, so you can build battleships instead. Here, we use the Battleship Armor II; the more armor you have, the less damage you take from light (and heavy) guns. These ships use the Dual-purpose Secondary Battery II; the countries GB, FRA, USA, Japan start with this 1939 technology.


These behemoths are the best ship for a strong strike fleet, if the enemy builds BBs. Their high armor negates even shots by battleships, and they can pierce normal battleships.Since they have much higher visibility than BBs, they will take more shots. Despite this, they still easily out-trade BBs.


Outdated design.
A popular strategy is to use roach destroyers; they would provide cheap screening for LA heavy cruisers. However, since LA heavy cannot be built anymore, this design is outperformed by an 'all-rounder' design from my own testing.



These ships provide light attack, making them excel at killing enemy screens. Defensively, these cruisers are all-rounders; decent armor to reduce damage taken from light guns, and their high speed combined with low visibility means they're hard to hit by heavy guns and torpedoes. These are the best ships for the screening line, but don't provide much screening for their IC cost. Make sure you have torpedo damage in your fleet, to exploit the gaps created once the enemy screening line has been destroyed.



These are only good at dealing torpedo damage. Once the enemy battle line becomes vulnerable after killing the enemy screens, this will cut through any battleship. Works very well in combination with LA cruisers. Only build these if you don't have ships with torpedoes in your starting navy.



Refitting is quite expensive, but massively upgrades your strike fleet. Armor refitting is never worth it. However, adding extra guns on empty slots is typically a good idea. Most importantly, there is one module you must refit for ships in your strike fleet which is Fire Control, since these increase your hit chance from base 10%, to 12.5% 15%, then 17.5% chance for Fire Control I, II and III. Ideally, make sure refitting ends just when the war starts.

Refit using the following button:




From testing, the BBs perform best if you go for the Atlantic Fleet Designer (extra armor+Heavy Attack). The Coastal Defense Fleet (cost reduction designer) gets beaten by the Atlantic Fleet designer for equal IC SHBBs.

Note: Building a ship using the 'cheap' designer company, then refitting using a quality designer, does not work anymore.

When Patrolling, you want to detect the enemy before they detect you. After you've found the enemy, you can:

• Observe them (recommended) from a distance, then call in a (small) strike force,
  
• Or directly attack them using that patrol force.

Be aware that the enemy will also be able to spot you; you'll want to be faster than the enemy at spotting, or they will destroy your spotting taskforce!

If you want to use your patrol to fight skirmishes, put the task force at low or medium risk; if you want them only to be used for spotting, use 'never engage'. Remember you can use small strike forces if you want to catch small fleets; no need to waste all your fuel. When enemy naval bases (holding a strike force) are far away, this hit-and run tactic can actually work; you'll have won the battle before the enemy strike fleet arrives.

Possible engagement risks.


The best design for a spotting taskforce is 1 Cruiser, filled out with sonar, radar, and floatplanes and anti-air. You don't need to deal any damage with this; it's meant purely for spotting. Make sure to put it to 'never engage', and you'll have an extremely good spotting force! After you have spotted the enemy, let a specialized strike force clean up the enemy. The anti-air on this ship is an effective way of killing lots of enemy naval bombers that operate from the land, and reduce damage taken from them.


The advantage of using 1 submarine for spotting is that submarines are much cheaper to replace, and can be used in combination with land-based naval bombers. If you decide to go for the naval bombing strategy, use 1 submarine, and put it to 'always engage', so that your naval bombers can do the damage, while your submarine hopefully stays hidden for long enough to survive. This is the quickest way of killing the enemy navy using planes, but you will lose some submarines doing this.


Spotting consists of 2 phases:

• Detect Submarines (only when the enemy has submarines): Find whether an enemy taskforce is present. This scales[hoi4.paradoxwikis.com] with the 'hourly change' value and the 'Base detection' value. This phase is skipped when detecting enemy surface ships.
  
• Hourly change: Pinpoint the enemy taskforce's exact location. After finishing this phase (reaching 100%), a strike force can start a battle. The starting value of the spotting is determined by 'base detection'.

Base detection determines at which % the spotting starts. The higher this number, the better.

Base detection is determined by:

• Base amount of detection. (10%)
  
• Amount of friendly ships performing a mission in that sea zone.
  
• Naval Intel difference.
  
• Friendly air supremacy: Acts as a multiplier (up to 2) to all the above!

Factors that affect 'hourly change' are:

• Intel efficiency: most important stat!
  
• Sub detection
  
• Surface detection
  
• Sub visibility
  
• Surface visibility

All of these numbers are the averages of your patrol group; that is why you want to use only 1 Spotting Cruiser, and nothing else. Sub detection is hard to come by, but more effective per-point (6x as effective) compared to surface detection.








Always get this upgrade!

Intel Efficiency acts as a multiplier to surface detection and sub detection:

• 0.5 at 0% intel, scaling to
  
• 1.0 at 40% naval intel.

Having intel is extremely important for spotting!

Ways to increase Naval Intel:

• Having a Spy Network in their country (up to 40%, requires a port in the spy network.)
  
• 'Infiltrate Navy' spy operation
  
• Decrypted enemy ciphers (10%, or 50% for 30 days when activated).
  
• Radar on ANY enemy Sea Zones.
  
• Spy planes.
  
• 'Naval Department' upgrade (1.25 modifier to total Navy Intel).

You can directly view your intel efficiency by going to the intelligence agency. You reach maximum spotting speed at 40% intelligence. In addition, this Intel Efficiency also gives Naval Supremacy; very useful for launching invasions. Extra Intel above 40% doesn't do much, but will still increase Base Spotting.

Convoy raiding in just 1 Sea zone can already reduce trade route efficiency by 50%!

Convoy raiding is one of the most important purposes of the navy; cripple their trade routes, and you'll block their access to valuable resources like oil and rubber. Supply to troops overseas can also be blocked by performing Convoy Raiding; troops on remote islands will attrition as a result.

The best ships for convoy raiding are submarines. However, your strike fleet is also good at raiding if you can spare the fuel costs.
Typically, players use around 10 submarines per sea zone; however, the more you have in a sea zone, the more convoys you will kill. There is no cap on the amount of ships sunk by a single task force.

Even though I generally wouldn't recommend researching naval tech (the navy supports the army), make an exception for submarines: submarines get MUCH better over time!

The 1940 Submarine, when combined with Snorkel, can be very hard to detect without proper patrol ships.

Your subs get even better with the 1944 Hull, combined with Snorkel II.

This sub will be your to-go design at the start of the game. Simple, but effective. Use them in groups of 10.

This design is a massive upgrade from the 1936 design. It is quite hard to detect, and will be nearly impossible to find by the AI.

Control the trade routes of your convoys by changing Access! Otherwise, convoys will always take the shortest route.

Protect your convoys by using the Convoy Escort mission. Your ships will:

• Chase away any convoy raiders attacking your convoys.
  
• Kill the enemy ships attacking your convoys.

You can use any ship (preferably leftover destroyers, anything can chase submarines away) for convoy escort, but for actually killing them (especially 1940 submarines), you'll need a specialized force.

You can only kill submarines by spotting them first!

The best way to kill Submarines (especially 1940 Submarines) is to use a Spotting Cruiser as a spotting task force, in combination with Depth-charge Destroyers. Alternatively, use a small strike fleet that includes 1 or more carriers (since carriers can also kill submarines). Submarines will be completely revealed and vulnerable if you are the one starting the engagement (after spotting). However, when you join your escorts on the defense, submarines will very quickly hide once your ships arrive, and then become untargetable.

Naval bombers are also good at killing submarines.



This design was designed to deal maximum Depth charge damage, for the best cost-effectiveness possible. It is not good at detecting subs, only at killing them. Use this ship either as a convoy escort or strike force: 1 ship per sea zone should be enough for chasing enemy subs away. When using it as a strike force, group them in groups of 5 (any size will do). Then put them to engage at Medium Risk.

A fully satured minefield will give the enemy numerous penalties:



Even though many players don't bother with minelaying, their effects are very strong!

The best zones to put mines are:

• Chokepoints, where the enemy will pass often.
  
• Your own coastline, to protect yourself against naval invasions.

You can place mines with a Surface ship or a Submarine. Destroyers are technically the most cost-effective at laying mines, but they are also much more prone to being spotted by enemy ships. Therefore, you should use submarines for minelaying.

Planes can be used for minelaying/minesweeping as well, but this is unlocked extremely late-game (1942), and requires quite some research. The naval game will have been decided by that point in time. Despite being unlocked very late, mine-laying planes are actually quite good.

This design has the cheapest torpedo (all subs must have at least 1 torpedo), en has minelaying tubes in it. You'll only need a couple of these to fully saturate a few critical sea zones with mines; 15 mine-laying subs should be more than enough.


Minesweeping can be performed only by surface ships. The most cost-effective at this is the Destroyer. You should only start building them after you notice the enemy starts laying mines, since the AI and players typically don't use mines.


A simple minesweeper design; it doesn't get any more cost-effective than this. You'll only need a couple of these, and only if the enemy actually has laid mines.

You heard him right: the best way to kill the enemy navy is to use naval bombers. In fact, you can kill ANY navy using plenty of naval bombers.

Naval Bombers are incredibly cost-efficient.

The 'Base Strike' doctrine actually gives numerous bonuses to Naval Bombers; if you want to navy without building a navy, go for this doctrine.

To use Naval Bombers, you'll want to have air superiority, in order to protect your naval bombers from enemy fighters. Clear the skies of enemy fighters before deploying Naval Bombers!


(This plane mission distribution has been proven in a reddit thread.)

Alternatively, split your submarine fleet in tiny stacks, then put them on raiding, with 'always engage' turned on.

If the enemy decides to use to defend their convoys, (which the AI will always do), they will then will then join the battle between your subs and their convoys. You can also try to spot the enemy fleet and then engage them using subs. Since your submarines started the combat, they will be able to hide as soon as the enemy fleet arrives. While hiding, your submarines will be near-invulnerable; neither side will deal any damage. However, since you are in combat, your naval bombers can kill the enemy ships during this battle(s). When using this strategy, put all naval bombers on Naval Strike.

Port strikes are very effective. Note that Port Strike has to be performed ABOVE the land where the port lies!

The only protection for your naval bombers against ships is agility, so the smallest airframes actually are the beefiest when it comes to air-ship combat.

The most cost-effective design for a naval bomber. The design can be improved (slightly) after 1936; the 1940 light airfarme has increased agility, which grants protection against ships, and the 1940 light airframe also has increased range.

This design uses a MG, since your primary weapon cannot be a torpedo for a Medium airframe. Therefore, use the blue-star reinforcement option, which allows only the exact same plane type to reinforce. The design main advantage of using this design is its range; it has a much longer range than a small airframe. You add modules to increase its range even further, but typically 1000 km or above is enough range for most seas.

Which doctrine to use depends on what you want to use your fleet for.

• You plan to have the strongest strike-force possible? Go for Fleet in Being.
  
• You want to search and destroy enemy submarines? Go for Fleet in Being.
  
• You only have submarines, and have no chance of ever killing the enemy navy? Go for Trade Interdiction.
  
• You are using Naval Bombers (recommended) to slowly dwindle down the enemy navy? Then Base Strike will be the best, as there are bonuses for normal naval bombers in this tech tree.
  
• You have a relatively small strike fleet, with 4 carriers in it. These carriers will thus form the largest component of your damage output. In this case, Base Strike is the best.

In the past, Trade Interdiction used to give reduced visibility to submarines, but this bonus was removed, making trade interdiction arguably the worst doctrine. However, it still grants the most bonuses to submarines out of all doctrines.




The best admiral stat is attack (+5% dmg), as this attack bonus will apply when convoy raiding, whereas defense (-5% damage taken) only applies when your ships get attacked. Therefore, instilled aggression is typically the best choice.



The Spirit of the Navy is quite varied; all of them can be good, depending on circumstance. Naval Refit Yards is the most all-round choice; it should be taken when refitting or when repairing.


Night Fighting.
This spirit gives you lots of raw stats; a 10% attack increase (at night) translates into an averaged 3-5% bonus (depending on the season) over the whole day. In addition, you also get 10% extra spotting at night, and -5% visibility without any drawbacks. This is the most practical spirit.

Decisive Battle.
(Only available if you have Fleet in Being). This spirit might on paper look better than Night Fighting, but Night Fighting is actually stronger.

Inclement Weather Experience
This Spirit reduces the Bad Weather effects by -40%; pick this if your fleet is mostly carrier-based, since carriers suffer greatly from bad weather.


CAG Night Fighting
This spirit, which can be found in the air force command, is an extremely strong spirit. It is unfortunately only available to Great Britain.

You can use your strike fleet (or any fleet) as an escort for troops performing a naval invasion by changing their mission to Naval Invasion Support.

To be able to perform a naval invasion, you need at least 50% Naval Supremacy in ALL sea zones the troops pass through. The typical way to gain naval supremacy, removing enemy naval supremacy (killing them).

Naval Supremacy is is determined by:

• Number of friendly ships on a mission, most importantly Patrol and Strike Force. Large ships contribute more.
  
• Minelaying (both friendly and hostile mines)
  
• Air Supremacy

Naval Supremacy is influenced by Air Supremacy and Mines.

Each Admiral level gives +5% hit chance (+5% DPS) and +2% coordination.

For a strike fleet, go for a high-level admiral with the highest attack+defense value, ideally having an equal amount of attack and defense.

For a Raiding Fleet, go for a high-level admiral with high attack.

Admirals have 4 base stats:

• Attack,
  
• Defense,
  
• Maneuvering and
  
• Coordination.

Of these, Attack and Defense are the most important, as these increase combat capabilities equally. For a battle fleet, it is best to have equal points in these. Combat effectiveness could be thought of as multiplying effective HP with damage, with defense being slightly better than attack.

Here, I define Effective HP as:
1/(1-defense%). Example: 1/(1-0.25) = 1.33 effective HP.

Maneuvering offsets the penalty for having a larger fleet than the enemy and the penalty for ships joining the battle after the start of battle. Note that by virtue of having a larger fleet will ensure you'll win the battle anyways, (despite the positioning penalty!), so all maneuvering does is letting you win harder when already winning!

Coordination is supposed to increase hit chance and mission efficiency according to the wiki. The total coordination is determined by admiral level and the coordination stat. How large its impact is, is not listed anywhere on the internet. Apparently, no one understands navy, not even Paradox themselves.



Make sure the admiral traits align with their goals; is the admiral meant for a strike fleet, or a submarine fleet?

Some notable Admiral traits:

• Concealment expert is the best trait there is; it grants -20% visibility, massively reducing your chance to get hit. For a destroyer being targeted by a light gun, the probability of being hit is reduced by ~33%. For a battleship being targeted by a heavy gun, the probability of getting hit by a heavy gun is reduced by ~10%. As an added bonus, it will be harder for the enemy fleet to spot you.
  
• Bold is excellent, as this gives both 5% extra damage and 10% extra speed (=extra HP).
  
• Tactician gives a 25% bonus to positioning, which is quite useful for your strike fleet.
  
• Spotter gives extra spotting speed, which is quite a lot as far as spotting bonuses go.
  
• Terrain traits like Blue Water Expert can be very good, as long as you fight in the terrain the admiral specializes in.
  
• Sea Wolf, Silent Hunter, Loading Drill Master and Torpedo expert (in that order) are excellent traits for increasing the damage output of your subs against convoys.

Naval Terrain will impact you and your enemy equally in a Naval Battle.
The same goes for Weather; weather penalties are applied to both sides!

Bad weather mostly affects carrier-based planes, so weather is especially important when you have a carrier advantage/disadvantage over the enemy. You cannot check the weather every second, however, so weather is typically an RNG factor in Naval combat.

You should pay attention to some terrain types, only when using Submarines:

• Shallow Sea increases Submarine Visibility by +100% (!!)
  
• Fjords and Archipelagos decreases visibility of ALL ships (including Subs) by -20%.
  
• Deep Oceans decreases visibility of Subs by -15%.

At the start of the game, merge all ships into 1 taskforce using the hotkey G.

• If you want to gain naval XP while using fuel efficiently, train the subs first, then destroyers, then Capital ships. Use shift+K to perform Naval Exercises until trained.
  
• Separate the submarines and put them under a separate Admiral. Turn them into smaller stacks by splitting them, using hotkey D.
  
• All other ships should be used as a strike force; set them as a strike force for selected sea zones. If you would get more than 4 carriers in this strike fleet, park it somewhere else.
  
• Split off ships that are good for spotting, put them on spotting duty.
  
• Put some destroyers (that have Depth charges!) for Convoy Escort under a separate Admiral.
  
• Send ships back to port using hotkey H, or use hotkey Ctrl+H to have your ships stay at their current location.
  
• Carefully check the engagement risk for every task force.
  
• Automatic Split-off is very useful for all task forces; however, turn it off if you still have to fight the decisive naval battle.
  
• Use Fighters (or other planes) to increase Base Spotting and Naval Supremacy. There is no limit to the amount of Base Spotting given by planes!
  
• Give priority to the Army and Airforce; they are more impactful than Navy. If you don't have any oil resources, don't exercise the Navy (or exercise until trained). The Civilian factory can then be used for building factories instead of trading oil.

Always increase the maximum number of Dockyards that can repair ships, to get your ships back in action quicker!

This guide does not contain much theory behind ship combat; if you wish to know more about ship stats and fleet composition, go the the wiki[hoi4.paradoxwikis.com], or watch this video:


If you have any questions or suggestions, put them as the comments below this guide. I'd gladly improve where necessary!