Naval units

This page deals with the mechanics associated directly with naval units.
For naval combat mechanics and fleet organization see naval warfare.

This article describes the different naval units and the statistics associated with them.

Types

There are four main types of ships: capital ships, screens, submarines, and convoys. Ships are organized into fleets. Each fleet contains a minimum of one ship and no maximum limit.

Capital Ships

As the main surface combatants, capital ships are designed to sink enemy ships in surface battles. They are expensive and require a relatively long time to build. As they are vulnerable to submarines and torpedoes, protecting capital ships with cheaper, quicker-to-build screens is a sensible strategy. As is the case for other warships, capital ships become increasingly vulnerable to attack from the air as aircraft technology and Air doctrines and naval doctrines improve over the course of the game.

• Super Heavy Battleships (SHBB): These are the largest vessels afloat during the period, with the most powerful guns and thickest armor. They are expensive (they are the most expensive type of vessel, and also the most expensive in terms of firepower per industrial capacity), but are the best vessels for slugging it out with other surface warships if cost is not a consideration.
• Battleships (BB): Standard battleships, like their super-heavy cousins, are designed to provide heavy firepower and an armored backbone during surface combat. They have the second-strongest gun attack and second-strongest armor of any capital ship (after Super Heavy Battleships), but are relatively expensive in terms of industrial capacity and resources.
• Battlecruisers (BC): Battlecruisers are slightly less expensive than battleships of the same year, with a little less armor and firepower but a little more speed. They are, however, substantially more capable (and expensive) than heavy cruisers.
• Heavy Cruisers (CA): The smallest and cheapest of capital ships, heavy cruisers are substantially weaker than other capital ships but outgun and out-armor screens handily. They have the highest efficiency in firepower to cost (piercing against other capitals not factored in). This makes them particularly good at sinking enemy screens.
• Carriers (CV): The ascendant ruler of the seas, carriers are nearly defenseless on their own but can strike from afar with their complement of aircraft.

Screens

Screens scout for the fleet and protect it from submarines and aircraft.

• Light Cruisers (CL): Bigger and more expensive than destroyers, light cruisers are "jacks of all trades", being able to engage targets below, on, and above the surface. Being "jacks of all trades" they fail at min-max where they are too easily sunk for the amount of good that they do. In other words, upon taking fire their usefulness is likely to end (from ships higher in the pecking order), although their evasion stat reaches capacity on benefits that it renders (dodging fire).
• Destroyers (DD): Cheap, fast, and flimsy, destroyers specialize at hunting submarines. In a pinch they can close for a torpedo attack. While in combat, they are the "butter" of the "bread" soaking up damage from the opposing fleet, through their evasion stat, which makes for the best investment so long as you've invested in making sure that they outlive enemy DDs. Their high torpedo damage will ignore armor, but ultimately isn't an efficient form of damage output due to in-depth naval mechanics.

Submarines

• Submarines (SS): Small, slow, and stealthy, submarines excel at sneak attacks on unescorted convoys and capital ships. Yet they don't belong in actual combat as they prompt other ships to prematurely flee with them in vain. On the whole, submarines are "cheap, slow, and stealthy" which is the only thing going for them. Submarines are near the bottom of the naval pecking order just above convoys. Against convoys, Level I submarines have an off chance that they will offset their cost before they're sunk.

Convoys

• Convoys: Not shown on-map, convoys carry troops, reinforcements, and lend-lease across water. They are defenseless against enemy warships and require an escort in times of war.

Hulls

TBD: specific base hulls that are unlocked through research. See historical ship variants for a list of historical variants.

Statistics

Each class of ship has a number of values referred to as stats. These are described below. Most of these stats can be improved by building a variant. However, be aware that increasing one stat will adversely affect a different stat. Reference Variant and Variant Upgrading and Variant Naval. Researching Naval doctrine can also increase stats.

Base stats

• Maximum speed. Maximum speed represents a value that indicates how quickly a naval vessel can move under optimal conditions. A faster ship has an easier time of disengaging from pursuers, can close to optimal fire range quicker, and can move faster into position when concentrating fleets.
• Maximum range. A ship's range represents its onboard stores of fuel and foodstuffs, which will limit how far it can travel from the nearest friendly Naval Base.
• Evasion. Evasion is the ability of ships to avoid enemy fire through maneuvering. When evaluating chances to avoid being hit, the target's evasion value is compared to the attacker, so that if you have high evasion, then you will also be more capable of hitting evasive targets; evasion is checked against enemy evasion, so high evasion improves hits against high evasion targets. When considering torpedoes, note that they are slow so evasion matters even more. Reference Defines NNavy COMBAT_EVASION_TO_HIT_CHANCE, Defines NNavy COMBAT_EVASION_TO_HIT_CHANCE_TORPEDO_MULT, and Defines NNavy MAX_EVASION_BONUS.
• Organization. Organization is an indicator of a ship's combat readiness. The higher the organization rating of a ship, the longer it can stay in a fight. A ship with low or no organization cannot fight or move effectively. Reference Defines NNavy COMBAT_LOW_ORG_HIT_CHANCE_PENALTY.
• Deck size. Deck size is a measurement of how many planes a carrier can fit on board. The act of exceeding a carrier's deck size (plane limit) is known as carrier overcrowding and it results in a penalty to carrier plane missions. For example, a carrier with a deck size of 45 is limited to a maximum of 45 planes before triggering the overcrowding penalty. Each plane exceeding 45 adds a mission penalty of approximately -4.4% per plane. If the total number of planes on this carrier was 55, then the 10 extra planes would result in a mission penalty of -44%. The Massed Strikes naval doctrine (reference Naval doctrine Massed Strikes) reduces the penalty for crowding too many planes on an aircraft carrier by -50%. In the example above, the Massed Strikes naval doctrine would have reduced the overcrowding mission penalty from approximately -4.4% to -2.2% per plane or from -44% to -22% per 10 planes. The Massed Strikes doctrine's significance is that it allows carriers to get more planes in the air even though over capacity. Bringing more aircraft to a fight is better.
• HP. HP is an abbreviation for "hit points" and is the ability to absorb damage. It represents strength which is how much damage a ship can sustain before being destroyed.
• Reliability. Reliability is the ability of a ship to continue functioning during combat. The lower the value the more likely the ship is of suffering a critical hit. Ships may receive critical hits that are much stronger than usual hits primarily because of exploding ammo or fuel tanks. Increasing a ship's reliability will reduce the chance that a received hit becomes critical. Note that the highest critical chance is done by torpedoes and not by a ship's main guns. Reference attrition and accidents.
• Supply use. How much supply the unit consumes per day. Please read Supply on the significance of this.

Combat stats

• Naval firepower. Naval firepower is a value that represents a ship's capability to damage enemy ships due to gun caliber, quantity of guns, rate of fire, etc. The higher the number, the better. Reference Naval warfare combat details.
• Torpedo attack. Torpedo attack is a value that represents a vessel's capability to damage enemy ships via torpedoes.
• Depth charges. Depth charges are a value that represents a ship's capability to damage enemy submarines via depth charges.
• Armor. Armor is a value that represents a ship's steel decking thickness, belt thickness, bulkheads, etc. The purpose of armor is to help protect a ship from attack. Having armor that is equal to or greater than the opponents piercing value makes you take less damage (-90%); reference Defines NNavy COMBAT_ARMOR_PIERCING_DAMAGE_REDUCTION. Having armor that is equal to or greater than the opponents piercing value also helps prevent an enemy ship from gaining a critical hit bonus; reference Defines NNavy COMBAT_ARMOR_PIERCING_CRITICAL_BONUS = 3.0 and Naval warfare.
• Piercing. Piercing is a value that represents the ability of a ship's guns to penetrate an enemy vessel's armor. Having equal or greater piercing to the target's armor value allows you to do more damage.
• Fire range. Fire range is the maximum effective distance that a ship's main guns can reach.
• Shore bombard. Shore bombard is a capital ship's ability to shell land troops using its main guns. Reference Naval warfare combat details.
• Anti-air. Anti-air, also known as Naval AA attack, is a value that represents how much firepower that a ship's anti-air guns can provide in shooting down enemy planes. This value adds a positive modifier to the "to hit" dice of friendly ships' attacks against air units. The higher the number, the better to protect against both land based and carrier based air attacks. The naval AA attack value also protects against port strike attacks. Researching the Grand Battlefleet Naval doctrine increases all of your ships' anti-air values by +10%.

Misc. stats

• Fuel Usage. How much fuel a unit uses while it is operating. Sea units will consume fuel while on active missions or during training.
• Port capacity usage. Port capacity usage is a value that represents the space that a ship requires while in a friendly port.
• Surface visibility. Surface visibility is a value that represents a ship's profile. This value is the "hide in shadows" score. The higher the value, the more visible a surface ship becomes making it more likely to be spotted and attacked. The smaller the value, the less visible the ship becomes making it harder to spot. The enemy can't destroy a fleet it can't see. For example, a Japanese fleet with minimal surface visibility score can sneak its surface fleet past Singapore in the Straits of Malacca. Surface visibility can be reduced (-10%) by hiring a raiding fleet naval design company such as Germany's Blohm & Voss or by researching the proper naval doctrine.
• Surface detection. Surface detection is a ship's ability to detect enemy vessels navigating on top of the sea (not under the sea such as submarines). A fleet can only engage ships if it knows they're there. A ship starts out hidden and has a chance to be spotted if it gets too close to an enemy ship (ships may also be spotted by aircraft). Reference Naval warfare Detection. Surface detection may be increased by the following means:

1. Adding more ships to a fleet or sea region
2. Adding more planes to a sea region (gaining Air Superiority)
3. Increasing radar in a sea region
4. Having better decryption than an enemy vessel's encryption (+20% improved detection for every level that your decryption is better than the enemy's encryption, reference Defines NNavy DECRYPTION_SPOTTING_BONUS = 0.2)
5. Researching higher level ships
6. Researching naval doctrines that include a bonus to surface detection

• Sub visibility. Sub visibility is a value that represents a submarine's outline. This value is the "hide in shadows" score. The higher the value, the more visible a submarine becomes making it more likely to be spotted and attacked. The smaller the value, the less visible the submarine becomes making it harder to spot.
• Sub detection. Sub detection is a ship's ability to detect enemy submarines. A fleet can only engage submarines if it knows they're there. A submarine starts out hidden and has a chance to be spotted if it gets too close to an enemy ship (submarines may also be spotted by aircraft). Destroyers are best at hunting submarines followed by light cruisers due to their high sub detection ability and use of depth charges. Capital ships are poor at sub hunting due to their low sub detection and lack of depth charges. Sub detection may be increased by the following means:

1. Adding more ships, especially destroyers and light cruisers, to a fleet or sea region
2. Adding more planes to a sea region (gaining Air Superiority)
3. Increasing radar in a sea region
4. Having better decryption than an enemy vessel's encryption (+20% improved detection for every level that your decryption is better than the enemy's encryption, reference Defines NNavy DECRYPTION_SPOTTING_BONUS = 0.2)
5. Researching higher level destroyers and light cruisers
6. Creating destroyer and light cruiser variants incorporating higher sub detection
7. Hiring an escort fleet design company such as the United Kingdom's Yarrow Shipbuilders (+10% sub detection for screen ships)
8. Researching naval doctrines that include a bonus to sub detection
9. Adding an anti-submarine specialist (+10%), anti-submarine expert (+15%), or anti-submarine genius (+20%) to the military staff

Unverified stat observations and commentary

• Surface detection and visibility along with sub detection are not precisely accounted for and are simply combined on the fleet level as per value present. A single battleship in a fleet of 100 destroyers will almost nullify any detection and visibility stemming from destroyers.
• Hit points is often a secondary factor to organization, evasion, and armor values since screening ships will often just die or quickly flee from a capital hit, while capital ships will "tank" with armor that reduces damage considerably, particularly if there is a substantial difference between piercing and armor (see explanation here). Aviation damage ignores 2 of these factors more often than not, reducing organization of capital ships that they will target more than anything, most likely not leading to a kill in themselves alone (as in bombers alone).
• Evasion has a hard upper limit on benefits it renders, light cruisers may surpass it.
• Anti-air attack is definitely useless against carrier based air power that will target capital ships (with screening ships' AA doing nothing), flying at least 2 sorties a day, and will always find its target (although capped at a max of 200 total planes per sortie).
• Sub attack is also not much of a factor since investing into airpower+carriers you're more likely to be dependent on carriers to kill revealed submarines rather than expecting destroyers to close in (with researched naval doctrines for escort efficiency), not that subs have much health for it to be a truly competitive matter to begin with.
• Shore bombardment has an upper limit on benefits it may render which requires only a few battleships.
• Torpedo attack fires every 4th time, has a 20% chance of being critical and doing decent damage, and may miss altogether (ignores armor, so a bunch of destroyers could kill a lone heavy ship).
• Operational range The operational range of a unit indicates the radius of operation for that particular type of ship on the map, from the closest friendly port (regardless of where the home port for the fleet containing that ship is based). A fleet that combines ships with different operational ranges will have a range that is the average of the individual ships.