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To build a navy, you need to plan ahead. Capital ships, which are the most important combatants, can easily take two years to build. On the other hand, ships generally do not cost too much IC at a time. In terms of IC-days, a Carrier or Battleship will only set you back about as much as single large armored division. Ships seem expensive only because your ultimate objectives will inevitably lie on the land—the navy's job is to help you toward those objectives, but in no case can they accomplish them alone. Still, in many cases you may find a strong navy indispensable.



Escorts serve a secondary, but important, role in navies. Unable to contend directly with capital ships, they are nonetheless useful for scouting, raiding convoys, and dealing with sub attacks. In combat, you need to have at least 1 screening ship (DD or CL) per capital ship or suffer up to a 33% combat penalty.

Destroyers (DD)

USS Fletcher, lead ship of her class. 175 Fletcher-class destroyers were built in all. Source: Wikipedia.

Destroyers are small, fast, cheap ships—perhaps 2 to 3 thousand tons in displacement. One destroyer unit represents a flotilla of destroyers. Unsuited for pitched engagements, destroyers are best used as scouts and sub hunters.


  • Cheap (for a ship)--comparable to 3 artillery brigades.
  • Fastest ship in the game.
  • Good at detection while not being very visible.
  • High Sub and Air attack.
  • Shares doctrine research with battleships.


  • Weakest surface action ship, both individually and per-cost.
  • Short firing and travel range.

Usage: With low Hull and hardly any Sea Defense, Destroyers have a hard time being anything but expendable. They can be used in small groups to hunt subs, but are not really suited for main fleet action.

Light Cruisers (CL)

HMS Belfast, today a museum ship. Source: Wikipedia.

Weighing in at 6 to 10 thousand tons in displacement, light cruisers form a heavier alternative to destroyers. Although still not able to stand up to capital ships in combat, they are far better than destroyers at doing so, at the loss of the destroyer's anti-sub and scouting capability. Possibly a better proposition than destroyers overall if you don't mind having to research in the Base Strike doctrine branch (the other two are fairly necessary at least for convoy escorting + targeting + battleships and base efficiency).


  • Cheap (for a ship)--comparable to 4 artillery brigades.
  • Fast.
  • Much better at surface combat than destroyers.
  • Better firing and travel range than destroyers.
  • Shares knowledge levels with Heavy Cruisers.
  • High Air attack


  • Significantly worse against subs than destroyers, and more expensive.

Usage: Slightly more durable than destroyers, but more importantly, with much more surface firepower, light cruisers are good for protecting main fleets as escorts.

Submarine (SS)

German Type VIIC/41 submarine U-995. More Type VII submarines were built than any other class in history. Source: Wikipedia.

Unlike conventional ships, submarines travel under the water, which makes them difficult to detect. During the World War II era, submarine technology was not strong enough to make them a powerful fleet asset. However, they are used to great effect in raiding unsuspecting convoys.


  • Cheap (for a naval unit).
  • Capital ships have little or no Sub Attack.
  • Great for gaining naval leader experience.


  • Extremely weak Hull.
  • Hardly any Sea Attack, thus highly vulnerable once detected.
  • Convoy sinking is not necessarily cost effective.

Usage: Submarines are best intended only for convoy raiding and can be used individually or in a wolf pack of 3 units maximum. Submarine warfare is an excellent way to gain significant amounts of leadership experience.

Capital Ships

Capital ships are the focus of naval combat. Whether due to their large guns and heavy armor, or by carrying aircraft, capital ships allow you to bring the most firepower and durability to a fight.

Battleship (BB)

German battleship Bismarck. She sank the HMS Hood in her first (and ultimately fatal) operation. Source: Wikipedia.

The pride of most naval fleets up until the later years of the war, the heavy armor and armament of battleships make them the most powerful gun ships in the world. Battleships dating back to World War I might displace as little as 18 thousand tons, but by the end of the war some battleships were pushing 50 thousand tons. Slow, unsubtle, and expensive, the battleship is the embodiment of brute force on the seas.


  • Extremely durable: 4 Hull and massive Sea Defense. When defense is taken into account, the battleship is the most durable ship per IC-day.
  • Long firing range.
  • High concentration of force.


  • Expensive.
  • No Sub Attack.
  • Slow.

Usage: Whatever may be said about Mahanian doctrine historically, it is sound where battleships are concerned—keep your big ships together and crush any weaker fleet that approaches. (Don't go too crazy with fleet size, though—there is a stacking penalty.)

Battlecruiser (BC)

Royal Navy battlecruiser HMS Hood, considered for many years to be the pride of the Royal Navy. Source: Wikipedia.

An attempt to make a compromise between the firepower of a battleship and the speed of a cruiser, the battlecruiser sports heavy guns with high speed, at the cost of armor. Meant to outshoot anything that could catch them and outrun anything that could outshoot them, their usefulness in the face of constantly advancing technology was questionable. Historically, they tended to displace nearly as much as contemporary battleships, the first battlecruisers displacing around 20 thousand tons, but reaching nearly 50 thousand with the famous HMS Hood.


  • Same speed as fleet carriers.
  • Decent concentration of force.


  • Almost as expensive as battleships, but quite a bit weaker in combat.
  • No Sub Attack.

Usage: Raiding convoys, though historically an intended role for battlecruisers, is probably not worth the mysterious damage battlecruisers will incur by doing so. One option is to use them as faster, weaker battleships. Radar and aircraft coverage will help them avoid unfavourable engagements. They are also an interesting alternative to battleships in terms of grouping with carriers, as, unlike battleships, they will not slow the carriers down.

Heavy Cruiser (CA)

Italian Zara-class heavy cruisers. Though well-armored for surface combat, their lack of radar proved to be a critical disadvantage. Source: Wikipedia.

The poor man's battleship, heavy cruisers are decent in most categories—cost, speed, firepower, and durability—but are unsuitable for forming a main battle fleet against a major navy. Heavy Cruisers were limited to 10 thousand tons by the Washington Naval Treaty, but the treaty did not hold forever; by the end of the war a heavy cruiser might displace up to 17 thousand tons.


  • Best Sea Attack per IC-day.
  • Fastest capital ship.
  • Cheapest capital ship (considering escort carriers need a CAG to be effective).
  • Shares practical with Light Cruiser.
  • High Air Attack


  • Poor concentration of force.
  • Less durable than a battleship per-cost.

Usage: In terms of industry, a nation that cannot afford a main battle fleet consisting of battleships or carriers, a fleet of heavy cruisers may be a good stopgap measure, especially as they share practicals with light cruisers. However, it does mean that a later switch to battleships or carriers may cost many techs.

Carrier (CV)

American aircraft carrier USS Enterprise. "Big E" earned more battle stars than any other American ship in World War II. Source: Wikipedia.

A newer type of capital ship, in World War II aircraft carriers began to take over from battleships as the most important ships in a navy. Although virtually helpless on their own, their aircraft can strike targets from far outside of the range of gun ships. Many aircraft carriers were converted from battleship and battlecruiser hulls; as a result, their displacements ranged from less than 20 thousand tons to over 70 thousand tons for the IJN Shinano, which was converted from a Yamato-class battleship hull.


  • Best naval vessel in the game without question.
  • Faster than a battleship.
  • CAGs can strike at extreme range.


  • Extremely expensive with CAGs—8.79 kICd, or just over two battleships.
  • CAGs vulnerable to attack, weather.

Usage: A carrier fleet can defeat any other fleet in the game with relative ease. Naval supremacy requires a strong carrier fleet, which can strike from a distance and destroy the strongest battleships in the water before they can even fire their guns on the carrier fleet.

Escort Carrier (CVL)

Japanese light aircraft carrier Shōhō, first Japanese carrier to be sunk in the Pacific War. Source: Wikipedia.

Classified as a capital ship by the game, escort carriers are smaller, slower, weaker versions of full fleet carriers. Historically, they displaced between about 8 and 25 thousand tons, and were used to escort slower ships such as transports and convoys.


  • Cheaper than half a fleet carrier.


  • Expensive with its CAG—4.09 kICd, or almost as expensive as a battleship (4.39 kICd).
  • Slower and shorter operating range than a fleet carrier.
  • Hardly any on-board detection capability.
  • No Organization or Morale upgrades.
  • CAGs vulnerable to attack, weather.

Usage: It is probably better to stick with fleet carriers if you want to go the carrier route—better concentration of force and speed, and not that much more cost. Otherwise, use them much as you would fleet carriers, though you may want to favor grouping them with slower ships.

Super-Heavy Battleship (SHBB)

Japanese super-heavy battleship Yamato, one of only two built. Her turrets each weighed as much as an average contemporary destroyer. Source: Wikipedia.

Unusually large battleships, these wildly expensive vessels carry the largest guns and heaviest armor of all ships. Historically, the only ships completed that could be considered to be in this category were the Japanese Yamato-class battleships, with a displacement of over 70 thousand tons at full load.

In game, these are crippled by their lack of upgrades.


  • High base stats.


  • No upgrades.
  • Extremely expensive.

Usage: Due to their lack of upgrades, it is probably better not to use these. However, nations that have no use for a navy until late game (such as USSR at war with Allies or a unified China needing to invade Japan) can make use of SHBB due to the necessary high firepower, as well as few required techs and no research slots needed for upgrades.


These ships may not be made for direct combat, but in the end they are the reason navies exist at all.

Transport Ship (TP)

D-Day landing on Omaha Beach. 4,126 transport vessels were involved in the Normandy Landings. Source: Wikipedia.

Consisting of troopships, often converted ocean liners, as well as landing craft, transport flotillas are essential for any nation which plans to conduct land operations overseas.


  • Cheap.
  • Necessary for transporting land units.


  • Slow.
  • Unarmed.
  • Short range.
  • No upgrades.
  • Doesn't share practical with anything else.

Usage: Use the Transport mission to ferry troops across shorter ranges; over longer ranges you will need to Rebase to a friendly port. Use Invasion to land troops on enemy soil. While transports can be attacked while in transit, the most dangerous part is when they are conducting an Invasion. Surveillance of the surrounding area by radar and/or aircraft and escorts are necessary to prevent undesired interference by the enemy. If necessary, split up your landings into smaller waves to give your escorts a freer hand to eliminate enemies who try to attack your transport ships.


Liberty ship SS John W. Brown. 2,751 Liberty ships were built in all, the most ever to a single design. Source: Wikipedia.

Convoys do not appear as a unit on the map. Nevertheless, they are necessary if you want to buy resources from other countries and supply troops overseas.


  • Extremely cheap.
  • Necessary for trade.


  • Unarmed.
  • Production doesn't benefit from practicals.

Usage: Build enough convoys to fill all your convoy routes; if you plan to be at war, keep some spares to replace losses from enemy convoy raiders. Getting convoys sunk decreases your National Unity, but you get a bit of compensation in terms of Naval Combat Experience.


Destroyer escort USS Evarts, lead ship of her class. Five more classes of destroyer escorts would follow during the war. Source: Wikipedia.

Like convoys, escorts do not appear on the map. Consisting of obsolete and cheaper destroyers, frigates, and corvettes unsuitable for accompanying main fleets, they protect convoys from harm.


  • Extremely cheap.


  • Production doesn't benefit from practicals.

Usage: Not necessary in peace, but in times of war they can reduce your convoy losses significantly (though the escorts themselves can be sunk as well). Automatic assignment gives about one escort per convoy, though you can increase this manually.

Landing Craft (LC)

New to TFH, Landing Craft work the same way as transports but are much more effective at naval invasions and have upgrades. They are slightly more expensive in IC cost than transports. Be careful not to confuse their code, LC, with light cruisers (CL).

Stack Size

TFH UPDATE For TFH, the hull stacking limit was increased to 16.

Fleets suffer a 4% stacking penalty to Positioning per point of combined hull size above 16. This penalty not only makes it harder for a fleet to hit the enemy, but also increases the chances of friendly fire. The hull values of all the ships in the squadron are added together. If the total is bigger than 16, you get positioning penalties in combat (they get in each other’s way). This penalty is 4% per point over 16 hull. So in theory, a total hull value of 16 or less would be ideal.

Due to stacking penalties, the maximum effective hull rating that a fleet can have is 16.8, which can be achieved with a total combined hull rating of 21 in a single fleet. Interestingly, while the stacking penalty has changed throughout the expansions of HoI3, this "sweet spot" of 17 has remained the maximum effective fleet size.

In practice, however, things look a bit different. A naval commander’s skill provides 10% positioning bonus per skill point. If Raeder and Donitz, for instance, have skill 4 and 5 respectively, they provide 40% and 50% bonus, enabling you to offset the penalty to a large degree. If the Kriegsmarine has a total hull of 18.42 this give us a 9.68% penalty. If we give Raeder command, his 40% bonus more than outweighs the penalty, in fact he can still apply a 30.32% bonus. A reasonable hull rate per ship squadron would be somewhere between 15 and 21. Using a good number of escorts, this translates to 10-13 ships.

Graph demonstrating the effective hull rating based on total hull size

How to calculate Hull values

Hull 1.80 1.90 1.54 1.54 1.28 1.30 1.20 0.50 1.00

This means that the following fleets will fit within the basic 16 hull limit or (on the last line), the 1939 scenario German fleet with a level 7 leader:

BB 5 5
CV 4 1 6
Mixed 1 2 3 6
CA 2 4 6
TP 2 1 2 5 2
1939 4 5 10 5


  • the Hull value also determines how much damage a ship can take.
  • The command stack size is 6/12/18/30 for naval units. Make sure your higher level skilled commanders have the highest ranks as the skill of the commander with the highest rank will be the one used in combat overall.
  • The average speed of all ships in a combat determines whether any will get into combat at all.
  • Put ships with the same speed together.
  • Don’t forget the Capital vs. Screen ratio. You need to have at least 1 screening ship per capital ship or suffer up to a 33% combat penalty. Screens are Light cruisers (CL) and destroyers (DD) and primarily exist to protect the capital ships. Capitals are heavy cruisers (CA), battlecruisers (BC), battleships (BB), escort carriers (CVL) and carriers (CV).

Shore Bombardment

For shore bombardment, only a few ships are needed to reach the maximum 25% damage penalty applied to bombarded enemy units. The Shore bombardment figure for each ship is the % shore bombardment penalty applied. This figure can be found on each ship's information screen, just add it together to find out the total. For example, two BB, one CA, one DD, and two CL together provides a total of 25% bombardment penalty.

Shore bombardment 0 10 7 0 3 1 0 0 0

Fleet Composition

Since stacking penalty is calculated per point of Hull, for nations that can afford multiple battlefleets, hull no longer greatly affects how effective a ship is overall, even for the same cost. The increased durability is offset by the decreased ability to concentrate force. This has the following effects on strategy:

  • Heavy Cruisers are now clearly the best surface combat ship, thanks to their high Sea Attack per IC-day.
  • Battleships and Battlecruisers are hurt the most.
  • Carriers gain relative to Battleships and Battlecruisers with this change; however, they now have more to worry about from fast Heavy Cruiser fleets.
  • Destroyers may now the escort of choice—with their low Hull and high speed they will quickly increase the speed of a fleet.

The optimum fleet composition may then be something like 6 Carriers and 12 Destroyers. In newer Versions of SF and FtM the stacking and hull penalties make fleets of 12 ships more useful. 4-5 capitals, rest screens. The air combat stacking penalty makes more than 2 carriers with 4 CAG's in total not very useful, but some CAG's at home to rotate damaged CAG's with rested full strength CAG's is recommended.

In the official HOI3 forum there is a thread which contains historical naval information, including pre-war naval expansion plans for every nation capable of building domestic warships and historical fleet compositions, as well as information on the roles each ship type played. This information is mainly of interest to players who wish to role-play and not worry about which fleet composition is necessarily the best. The link to the thread is here:


Exploits aside, there are a few combinations of ships that work with each other very well:

  • Battleships and Destroyers both share the same doctrine tree and complement each other very well. While big guns on Battleships decimate enemy navy, Destroyers add to detection of the fleet, take care of Submarines and chase faster enemy ships once they try to escape combat (Carriers especially). Due to low range of Destroyers researching Battleship engine beyond 1938 level isn't necessary saving one research slot. Suggested for Italy and the UK.
  • Carriers and Light Cruisers also share same doctrine tree and work together in a similar way BB+DD works. Lack of heavy-hitting guns and too cavalier escort behaviour allows enemy to take a few more shots at smaller ships while Carriers are far away and can't take their share of damage. So using another type of heavier ship with this combo is advised.
  • Battlecruisers and Carriers with 1940 engines have very solid 25 kph speed and very long 5500 km range (which is enough to reach Hawaii from Shanghai). If engine research of capital ships stops at 1940 level, Light Cruisers will match big ship's 5500 km range in 1944 allowing to create very fast and versatile stacks built around Carriers but also with help of Battlecruiser armour and big guns to sink enemy ships faster. Suggested for Japan and the USA.
  • Light and Heavy Cruisers share the same practical knowledge and building time. This allows to churn them out of shipyards at insane rate making them Militia equivalent of the high seas. They are the best choice to spam enemy waters with numerous fast ships and overwhelm his navy and shipping lanes.
  • Heavy Cruiser and Battlecruiser share doctrines improving their organization and morale meaning that when you research one of them, you also upgrade the other one. This means that fielding a navy of pure Cruisers also is a viable choice.

Average Fleet Speed

It is also important to note that the average speed of the fleet is what determines if ships close during combat. As a result, adding as many fast screens to a fleet will help with closing speed.

Here's an example of how average fleet speed can matter.

Speeds listed next to the type

US Fleet IJN Fleet

CV - 22 BC -21

CV - 22 HC - 23

LC - 24.5 HC - 23

LC - 24.5 LC - 24.5

LC - 24.5 LC - 24.5

LC - 24.5 LC - 23

DD - 25 LC - 24.5

DD - 25 LC - 24.5

DD - 25 DD - 25

DD - 25 DD - 31

DD - 25 DD - 31

DD - 25 DD - 29

DD - 27 DD - 29

DD - 27

The US Fleet has an average speed of 24.7 and the IJN Fleet has an average speed of 25.6. In this battle the IJN surface ships closed with the US carriers and the US carriers were destroyed by the IJN fleet.

I then removed the two DDs that had a speed of 31 to reduce the IJN Fleet's average speed to 24.6 which is 0.1 MPH slower than the US fleet. The IJN ships did not close with the carriers and the US Fleet won the battle without losing a single ship.


Unlike land provinces, one cannot see into adjacent sea provinces. Furthermore, even brief naval battles tend to be devastating to one or both sides. Therefore, it is important to know where the enemy is, in order to be able to create favourable engagements and avoid unfavourable ones. Options include:

  • Radar. A level 10 radar has comparable cost to a battle-cruiser, and covers a large area.
  • Aircraft. Due to their high speed, aircraft are excellent for spotting enemy fleets, especially those large enough to pose a major threat.
  • Ships. As a last resort, ships can be used to look for the enemy. However, a large fleet is obvious (though it has the advantage of being able to handle itself against whatever it finds), whereas a small fleet may not survive contact with the enemy.