User:Bitmode/Naval warfare

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See also: Naval warfare

Naval warfare is combat on sea provinces and the deployment of naval units that lead up to it. It allows countries to protect their naval troop transports and marine trade connections or denying the enemy these capabilities. Through aircraft carriers the air warfare can be influenced in otherwise hard-to-reach areas.


The unit overview of a carrier task force called "Singapore Squadron", part of the "Far East Command" fleet, docked in Singapore

Task force

In battle each ship can act individually to a degree. Outside of battle the task force is the smallest controllable naval unit on the map. Its stats are the averages of its ship's stats. The exception are speed (minimum) and fuel consumption (sum).

Task forces can be created and restructured in several ways. Newly built ships join the task force they were assigned or a reserve fleet. Existing fleets can be split in half or split in a custom way using the options above the task force's unit view. Selecting ships and right clicking another task force reassigns them there. Selected ships can be automatically distributed in balanced task forces, which attempts to create task forces with good ratios of screens, capital ships, and carriers.

To maintain the current composition even after a task force takes losses, the Automatic reinforcement option can be enabled. It will pull ships from the theaters reserve fleet to fulfill reinforcement request. The targeted ship counts are shown below the current ones. Finally the task force composition editor allows changing the desired number (and with Man the GunsMan the Guns the specialisation}}) of ships that will be automatically deployed to the task force.

Repair options

  • Automatic split off Automatic split off: Allows the most heavily damaged ships to detach and return to a close by naval base for repairs while the rest of the task force continues its mission. The detached ships are very vulnerable to attack while they return. After completing repairs, the ships will return to their assigned task forces. The amount of ships detached depends on the repair priority setting as well as the damage to each individual ship.
  • Repair priority Repair priority: Sets how severely a task force has to be damaged before it returns for repairs.
  • Repair now! Repair now!: Explicitly orders an individual ship to return to port as a detached task force for repairs. Shift-clicking on the button will allow multiple damaged ships to be detached as one task force.

Engagement rules

engagement rules The engagement rule controls how aggressive a task force behaves. For example on High risk submarines will attack all enemy ships, including screens.


Fleets can be led by an admiral and group multiple task forces that operate in the same area. All task forces under an admiral benefit from their bonuses. A single admiral can command up to ten task forces before their effectiveness gets reduced.


Just like in land combat, fleets are grouped into theaters. A theater can have an increased alert priority, to give the player more notifications of what is happening. Each theater has its own special reserve fleet.


The reserve fleet contains task forces that are not assigned to any particular fleet and have no active missions. They can either be moved into other fleets or, more commonly, their ships are used to fulfill automatic reinforcements from other task force.


Missions can be assigned to task forces and determine how they behave in the context of their fleet. Most missions make the task force operate across the whole operational area of the fleet.


Cancels the current mission and moves the fleet to the closest port. Control-clicking the mission makes the task force stay in its current province. A task force on hold doesn't consume fuel. When positioned on a sea province, it can provide shore bombardment bonuses to adjacent land battles and block connections between land provinces (except the ones in Denmark). It can still engage in combat if an enemy fleet is on hold in the same province.


A German submarine task force in the process of being spotted by the British Humber Force.

A patrol task force operates in a single strategic region, so a fleet should have one for each region in its operational area to cover them all. They continuously operate in their respective region, looking for enemies. Once they successfully spotted an enemy they can call in strike forces to deal with it. The spotting progress starts at base spotting chance and increases by hourly change until it reaches 100%. If the hourly change would be zero or negative, the task force can't spot that enemy. The patrol can only start spotting enemy submarine forces with a probability of each hour. A patrol can only spot one enemy task force at a time and vice versa.

Base spotting chance

The base spotting chance is where the spotting progress starts and influences how likely submarines can get spotted. It is the sum of:

  • 1% base base spotting
  • task forces in region: +10% if taskforces are present
  • air superiority: up to +20%
  • RADAR: up to +5%
  • decryption: up to 10%,

Bad weather can reduce the chance.

Hourly change

Hourly change is the speed at which the spotting is progressing.

  • mission detection multiplier: (10% + 10% * <radar coverage> + 25% * <air superiority>), gets reduced by bad supply and increased by Spotting chance modifiers (e.g. Man the Guns Search Pattern Expert trait)
  • Surface detection: where P() is the average respective stat of ships in the patrol force and E() in the enemy task force
  • Sub detection: the same with submarine instead of surface values
  • Speed difference: if the enemy is faster, if they aren't

The hourly change is the sum of surface detection, sub detection, and speed difference. The admiral's naval coordination increases the hourly change.

Strike force

Strike forces usually stay in port to conserve fuel and will only engage enemies after they have been spotted by a patrol.

Convoy raiding

A convoy raiding task force tries to sink enemy convoys in their mission area. Every game hour the task force tries to look for convoy targets, updates the spotting progress on an existing target or upgrades it target. It starts a convoy battle once 100% spotting has been achieved.

If the task force has no target at all yet, there is a 4.12% chance to consider regular (non-troop transport) convoys. This probability gets scaled by the convoy raiding efficiency (see below). When it does, there is a random chance for each enemy convoy route leading through the area of operations to be selected as a target. The probability is 0.05% * base spotting + 0.5% * spotting speed.

Convoy raiding efficiency

A raiding task force's efficiency gets reduced if the fleet covers too many strategic regions. The efficiency is the number of currently operating raiding task forces in the fleet, multiplied by 1.5, the Naval coordination modifier (scaled by 1.5), and the task force's raiding coordination, divided by the total number of regions the fleet covers.

Convoy base spotting value


Convoy spotting speed


Convoy escort

Convoy escorts protect convoys in their mission area. TODO number of ships needed, efficiency.

Mines planting

Man the Guns

Mines sweeping

Man the Guns

Naval exercise

Order a task force to perform exercises in the region adjacent to the closest naval base. This has a chance to damage ships over time. The crew will not gain experience once they reach the Regular level. You will gain Navy experience while training. The Pride of the Fleet is less likely to get into an accident.

Naval invasion support

Order ships to escort naval invasions and support them with shore bombardment.

Navy Overview

Navy Overview screen.

The Navy Overview can be opened by pressing the P hotkey or clicking on the Navy Overview.png Navy icon in the top right corner of the screen. This will bring up a summary of the country's naval forces currently deployed (not those under construction), as well as any bonuses or penalties currently in effect for a range of naval-related modifiers due to technology research. Directly underneath these values are the number of each type of ship, displayed as a silhouette, a naval designation for the ship type and a number.

Below that overview is a list of fleets, their type, name and location, as well as the number of ships in each fleet and its current mission. Left click on any fleet to select it. Right clicking on a fleet in this list will center the map on that fleet.

Naval Equipment List

Also in the overview are two small icons, Sunk ships button.png Lost Ships and Equip overview button.png Equipment Details.

Lost ships will open a window that lets you see a list of ships of the player that have been sunk in the last two years (it's time limited to help manage system resources).

Equipment details lets the player see the deployed ships not only by category (Carrier, Battleship, Submarine, etc) and quantity but also by ship class and quantity. This tool provides the player with information to let the player decide if a particular category of ship is made up of older hull types and could use newer class ships in that type, as well as help the player judge the overall make-up of his navy.


A battle gets initiated on a specific province between two task forces, one of them being the attacker. This usually happens after a spotting process is complete or opposing fleets move onto the same province. Naval and port strikes by air wings trigger a naval battle that lasts a single hour. Otherwise the battle lasts until one side is fully escaped or destroyed. The defender always joins the battle with full efficiency while the attacker may have a reduced efficiency depending on circumstances.

Inside of battles ships can behave independently and convoys, which are normally abstracted, are also present as individual ships.


  • Screening group: The screening group holds all the screening ships - usually light cruisers and destroyers - tasked with keeping enemy screening ships away from the main battle-line. Insufficient screening will allow enemy screens to make torpedo attacks against the battle-line.
  • Battle-line: The battle-line provides the main direct firepower of the fleet, usually in the form of battleships and heavy cruisers. They will also prevent enemy capital ships from firing at friendly carriers.
  • Carrier group: The carrier group provides the main long range striking power of the fleet. Screened from the enemy by both the screening group and the battle-line, the carriers can launch strikes on the enemy without interference. Should any convoys be present in the battle, they will also appear in this area.

Screening efficiency

The ratio of screening ships and other ships is the screening ratio. Optimal screening efficiency is reached when the ratio is 4. High screening efficiency prevents enemy torpedo attacks against the back lines and gives increased hit chance (up to +40%) and retreat speed (up to +20%) bonuses to ships in the battle-line and carrier group.

The ratio of capital ships to carriers and convoys is the carrier screening ratio. Optimal carrier screening is reached when the ratio is 1. High carrier screening efficiency further prevents enemy torpedo attacks (stacking diminishingly). It also provides increased sortie efficiency (up to +10%) to carries and increased retreat speed (up to +20%) for both carries and convoys.

Weapon cooldown

All weapons except torpedoes can fire every hour. Torpedoes normally fire every 4 hours (Man the Guns this can be reduced to 3 with the Drill Master trait).

Target selection

Each ship with offensive weapons (i.e. not carriers and convoys) and the respective weapons off cooldown can target three enemy ships independently per combat hour; one with its depth charges/light weapons, one with torpedoes, and one with heavy guns. Depending on weapon type and enemy screening, only certain enemy groups can be targeted.

  • Depth charges: the only weapon type that can target submarines, and only if they are revealed
  • Light guns: can only target the closest non-empty group
  • Heavy guns: can target the first two non-empty groups
  • Torpedoes: the probability that a torpedo can target ships past the screening group is 100% minus the enemy screening efficiency. To target ships in the carrier group (including convoys) it needs to pass an additional check of 100% minus the enemy carrier screening efficiency.

Submarines will only target screens when set to High risk engagement rule. They will only target capitals when set to Medium risk or higher.

Out of the remaining valid targets one is chosen by weighted random selection. If the firing ship is not currently running away, the enemies are weighted as follows (numbers in parenthesis for light guns)[1]:

  • capitals: 30 (2)
  • screen: 3 (6)
  • submarine: 4
  • carriers: 15 (1)
  • submarine vs convoy: 600 (40)
  • non-sub vs convoy: 60 (4)

If the target is lacking HP, up to +100% bonus are applied to the weight. If the enemy is escaping, the weight is reduced by 50%. If the enemy is actively fighting (i.e. not waiting), a +50% bonus is applied.

The weighting is similar when the firing ship is escaping but only considers targets that are actively fighting.

Hit chance

The base hit chance is 10%, 20% for depth charges. If the firing ship is lacking manpower or organization, the chance is reduced by up to -25% and -50% respectively.

Hit profile multiplier.png

Another factor is the guns hit profile compared to the target's profile. Small, agile ships are harder to hit, especially for bigger and slower guns. The hit profile of a ship is its surface/sub visibility multiplied by 100 and divided by its speed. Subs use their sub visibility, even when revealed. The hit profile of convoys is always 120. This profile is divided by the gun's hit profile (light: 30, heavy: 50, torpedo: 180, depth charge: 120) and then squared. It factors into the hit chance but can not increase it.

The hit chance can also be influenced by bad weather, night, screening bonuses, and the ship's admiral's level, logistics and planning skills.

Man the Guns Torpedo Expert and Destroyer Leader traits can increase the hit chance for torpedoes.

The hit chance is always at least .05%[2].

If the hit chance doesn't result in a hit, the target remains unaffected.

Armor piercing

Whether a weapon can pierce the enemy's armor has a great influence on the damage dealt. If the piercing value of the weapon is higher than the enemies armor, it increases the chance of critical hits. If it is lower the damage will be reduced accordingly. Torpedoes ignore armor.

Outgoing damage

The respective weapon type damage of the ship can get modified by doctrines, the naval terrain, the weather, Pride of the Fleet if present, and the admirals skills and traits. Bad positioning can cause a penalty of up to 50%. The Defense modifier of the enemy admiral's skill level will also reduce the damage.

If the weapon can not pierce the enemy armor, damage is reduced by up to 90%, scaling with the ration between the two.

The damage gets randomized by ±<span class="explain" title="half of 30%">15%.

Damage is applied against both the target's HP and organization, but organization damage will be relatively low while the ship's HP are close to full.

Critical hit

A critical hit is a particularly devastating hit against the target. Which can also damage some of its critical components. The resulting penalties can only be removed by repairing the ship.

The chance for a torpedo to score a critical hit is 20%. For other weapon types the base chance is 10% but also depends on whether the armor can be pierced (doubling the chance) and the target's reliability (sclaing down to 0% at 100% reliability).

Man the Guns The Marksman and Chief Engineer traits can respectively increase and lower critical hit chances, irrespective of weapon type.

If a critical hit does occur, it potentially affects one of the critical parts on the ship. The chance for this is 10%, inversely scaled by reliability (e.g. at 25% reliability the chance increases to 40%). If a critical part is hit the effects depend on the specific part. For example if the ammo storage is hit, the hit damage gets massively increased, while a hit to the rudder does only minor damage but cripples the retreat speedof the ship.

If a critical hit occurs without damaging a particular part, the regular damage gets doubled for torpedoes. For other weapons the bonus ranges between +100% (at 100% reliability) and +500% (0% reliability).

Naval strike

Every 8 hours (00:00, 08:00, 16:00) planes can sortie in the battle.

The number of external planes is limited to: <sum of all enemy ships' current HP> * 0.05 * (1 + 0.2 * <combat days>). But at least 20 planes can always join.

Target selection

The naval strike target is randomly selected from a weighted distribution. The base weight is each ship's maximum HP. This gets scaled depending on ship type:

  • revealed submarine: x10
  • capital ship: x50
  • carrier: x70

Damaged ships get a linearly increasing weight up to +500% at 0% HP. If a ship's anti air attack is below 5, the weight is increased by 5 * (5 - <ship/convoy AA>). For example convoys have only 0.2 anti air attack, increasing their score by 24.

Ship AA defense

When a ship gets targeted by an air wing, it will try to shoot back. Against non-kamikaze wings the ship's chance to shoot back is (90%+50%*(90% - 1%*<wing's agility>)) * 20%. If the attacker performs a kamikaze attack, the ship can always shoot back and its AA attack gets increased by 2. The highest possible number of planes that can be shot down is .5% of planes times the ship's AA attack. The effective number of planes shot down is a random number between 0 and this maximum. The losses are increased to 400% for kamikaze strikes.


If any planes remain after the ship shot at them, they perform the naval strike. If they are based on a carrier that takes part in the battle, their damage is increased to 500%. The ratio of planes that actually hit the ship is <naval targeting> * 30% (capped between 0% and 100%). It does not depend on the maneuverability of the ship.

The ship's AA damage reduction further reduces the damage dealt: 0.15 * (<ship AA (0 for convoy)> + 20% * <all ships fighting on same side AA>)^0.2

<ship AA> is 0 for convoys but convoy AA is included in <all ships fighting on same side>. The damage reduction can not exceed 50%.

Critical hits are calculated the same as a regular ship gun hit that pierces armor.

If the naval battle was a port strike, the naval base gets damaged proportionately to the damage dealt against the ship.

Carrier stacking penalty

Each carrier exceeding 4 per side incurs a 20% penalty, up to 80%. The penalty reduces the number of carrier wings that can operate.

Shore bombardment

Bombardment of Chinese forces

Any surface ships that are on hold in a province adjacent to a land battle provide a shore bombardment bonus. The bonus can be up to 25% (reducing the enemy's attack and defense). Every point of heavy gun damage provides 0.1% bonus and each point of light gun damage 0.05%.

  1. these numbers can not be modded
  2. but effectively it can't go lower than .1% due to the implementation