Europa Universalis 4 Wiki
This page deals with the recruitment and maintenance of navies. For naval combat mechanics see naval warfare. For details about ship types see naval units.

A navy is a country's naval (sea) forces.


The basic unit of naval forces is predictably the ship. Each ship is classed as heavy, light, galley or transport.

Ships are grouped into fleets. Each fleet can be led by an admiral or explorer. A fleet travels at the speed of its slowest ship class.

Building shipsEdit

Building ships requires an owned, cored and controlled   province with a port,  ducats to pay for the costs of the ship,   time to build the ship and   sailors. Each province can build one ship at a time, though multiple ships can be queued up in a single province.

The base cost and building time of a ship depends on its type, and is then adjusted by any modifiers, in particular those coming from buildings the province might have. Ships start with 50% of maximum   morale when they have been built. Going over the   naval forcelimit will result in higher maintenance cost.

Unlike land units, ships do not automatically upgrade to new models as technology advances. Fleets are modernised by building new ships, or by manually upgrading existing ships with the   Art of War DLC enabled.

Ship costEdit

The ducat cost for ships is computed as follows:


The sailor cost of building ships is depends on the ship model and does not get changed by any existing modifiers.

Base costEdit

The base cost for building ships is:[1]

Ship class   Ducats   Sailors
  Heavy ship 50 200–900[2]
  Light ship 20 050–150[2]
  Galley 10 060–180[2]
  Transport 12 020–100[2]

Ship cost modifiersEdit

Ship cost can be affected by general and ship type-specific modifiers which are added additively.

General modifiersEdit

General modifiers reduce the ducat cost of all types of naval units. All modifiers that reduce the cost of new ships also reduce the maintenance of existing ships by a corresponding amount.

Ideas and policies:

  Traditions Ideas Bonuses Policies
  • Acehnese/Pasai traditions
  • Bruneian traditions
  • Ligori traditions
  • Malayan Sultanate traditions
  • Manx traditions
  • Ouchi traditions
  • Palembang traditions
  • Maritime idea 5: Ship's Penny
  • Ajuuraan idea 1: Maritime Enterprise
  • Australian idea 5: Royal Australian Navy
  • Bremen idea 7: Foundation of Bremerhaven
  • Breton idea 5: Protect the Coastline
  • Canadian idea 7: The Forests of Canada
  • Chosokabe idea 5: Expand the Navy
  • Gutnish idea 3: Expand Visby Dockyard
  • Hamburger idea 7: Shipyards of the Elbe
  • Javan idea 6: Modernized Ship-Building techniques
  • Karelian idea 2: Between Two Seas
  • Maratha idea 7: Expand Maratha Navy
  • Neapolitan idea 5: Expand the Arsenale
  • Norwegian idea 4: Military Shipbuilding
  • Ottoman idea 7: Found the Imperial School of Naval Engineering
  • Scottish idea 2: Modernize the Royal Scots Navy
  • Maritime-Defensive: The Fleet is our Wooden Wall
  • Hanseatic idea 2: The Handelsmarine
  • Ragusan idea 5: Port Gruz

Additional modifiers:

−33% as optional difficulty bonus (for the player (very easy) or the AI (very hard))
  • with   parliament and “Expand Navy” as active issue
  • for   Tengri nations with   Ibadi secondary religion
−5% for trading in   wool

There are also many modifiers that affect ship cost and local ship cost of specific provinces from decisions, events and missions.

Class-specific modifiersEdit

Class-specific modifiers reduce only the cost of one ship class.

Heavy shipEdit
+1% for each percentage point of inflation[3]

Ideas and policies:

  Traditions Ideas Bonuses Policies
  • Date idea 5: Red Seal Ships
Light shipEdit
−20% with   ‘Private Trade Fleets’ privilege granted to   Burghers,   Vaishyas or   Jains estate
−10% with   parliament and ‘Issue Letters of Marque’ as active issue
+1% for each percentage point of inflation[3]

Ideas and policies:

  Traditions Ideas Bonuses Policies
  • Arakanese traditions
  • Balinese tradition
  • Butuan traditions
  • Malagasy traditions
  • Mogadishan traditions
  • Navarran traditions
  • Pomeranian traditions
  • Siddi traditions
  • Swahili traditions
  • Cham idea 2: A Seafaring People
  • Flemish idea 5: North Sea Shipyards
  • Gujarat Sultanate idea 4: Gujarati Merchant Diaspora
  • Hanseatic idea 3: Improved Shipbuilding
  • Novgorod idea 7: Baltic Shipyard
  • Somali idea 1: Maritime Heritage
  • Sulawesi idea 3: The Prau
  • Veronese idea 7: For Never Was There a Tale of More Woe
  • Catalan traditions
  • Galician traditions
  • Sulu traditions
  • Danziger idea 5: Danziger Shipyards
  • Omani idea 5: End of the Shipbuilding Guilds
  • Maritime-Plutocratic: The Protected Shipping Lanes Act
  • Pisan idea 6: Maritime's legacy
  • Sonoran idea 5: Taking What’s Ours
  • Naval-Trade: Fortified Trading Posts

There are also many modifiers from decisions, events and missions that affect light ship cost.

+1% for each percentage point of inflation[3]

Ideas and policies:

  Traditions Ideas Bonuses Policies
  • Genoese idea 4: Build the Genoese Arsenal
  • Cypriot traditions
  • Greek traditions
  • Ionian traditions
  • Barbary Corsair idea 2: Galley Slaves
  • Kono idea 2: Integration of Cadet Branches
  • Italian idea 3: Mare Nostrum
  • Maritime-Quantity: Streamlined Galley Production

There are also some modifiers from decisions, events and missions that affect galley cost.

+1% for each percentage point of inflation[3]

Ideas and policies:

  Traditions Ideas Bonuses Policies
  • Ando traditions

There are also modifiers from decisions, events and missions that affect transport cost.

Shipbuilding timeEdit

The shipbuilding time of a ship is computed as follows:


Base timeEdit

The base time for building a ship is:[1]

Ship class   Days
  Heavy ship 730
  Light ship 365
  Galley 365
  Transport 365

Shipbuilding time modifiersEdit

Shipbuilding time can be affected by countrywide and provincial modifiers which are added additively.

Countrywide modifiersEdit

These ideas and policies affect the shipbuilding time of naval units:

  Traditions Ideas Bonuses Policies
  • Australian traditions
  • Icelandic idea 2: Legacy of Hrafna-Floki
  • Couronian idea 4: Booming Manufacture
  • Genoese idea 7: Standardization of Designs
  • Omani idea 2: Securing Timber Supplies
  • Pisan idea 1: Restore the Pisan Navy
  • Ragusan idea 5: Port Gruz
  • Naval-Administrative: Harbor Administration

Additional modifiers:

+2% for each point of   war exhaustion
−15% with ‘War Against the World Doctrine’ government reform (tier 5  republic)
Provincial modifiersEdit
+20% for being   blockaded
+10% for each point   local unrest
−1% per   base production level
−10% for having a   impressment offices in a province which does not produce   Salt,   Fish,   Naval supplies,   Tropical wood
−20% for having a   impressment offices in a province which does produce   Salt,   Fish,   Naval supplies,   Tropical wood
−25% for having a   shipyard
−50% for having a   grand shipyard

Drafting Transport ShipsEdit

The government reforms Eastern Plutocracy, Kongsi Federation, Livonian Admiralty and Livonian Plutocracy, allow the cheap drafting of transport ships.
This adds a new template to the macrobuilder, which will dynamically include enough transports so that after building it, 80% of the force limit will be made up of transports.
Building these tranports will only take 50% of the normal time and cost 20% less sailors.
The monetary cost will be 1 years worth of income, multiplied by the percentage of forcelimit thats being build (80% = 0.8).
At the least, they will be 20% cheaper than regular transports (this is relevant for nations with very high yearly income).
The lowest price the template can reach is 1 ducat per ship (this is relevant for poor nations), unaffected by further reductions to ship cost.
Exept for this, reductions to ship cost interact normally with drafting.

Upgrading shipsEdit

When docked in an owned and controlled port, ships can be upgraded individually or at the fleet level. When an upgrade is triggered, the relevant ship(s) are replaced instantly, but reduced to an initial 1% condition to simulate the replacement ship being built virtually from scratch. For each ship, an upgrade costs the same amount of ducats as building a new ship.

Advantages of upgrading include:

  • The 'construction' process (i.e. repairing the ship from its initial 1% condition) takes only 10 months, which is generally faster than simply building a new ship, especially for heavies.
  • Upgrades bypass the build queue and so are not limited in speed by the availability of coastal provinces for building.
  • The original name of each upgraded ship is maintained.
  • Upgrading is more convenient than manually destroying older ships and building new ones.
  • Upgrading, rather than disbanding and rebuilding, maintains the presence of a fleet where that is desirable, e.g. for deterring attack. (Alternatively one could temporarily go over force limit before disposing of the excess ships.)


  • Repairing from 1% does not benefit from ship construction speed bonuses. (But it does benefit from ship repair bonuses, and repairing is generally faster anyway.)
  • Upgrading destroys the value embodied in the old ship, which could have been partially recouped by selling it to another country. Selling and rebuilding can therefore be more cost effective, where there are countries willing to buy.

Forcelimit and maintenanceEdit

 Force limitEdit

Main article: Force limit

Each country has a naval force limit, largely dependent on the total amount of development in coastal provinces and eventual coastal centers of trade.

Ideas which grant forcelimit bonuses:

  Traditions Ideas Bonuses Policies
  • Dutch traditions
  • Northeastern traditions
  • Maritime idea 4: Grand Navy
  • Danish idea 3: The King's Sea
  • Knights Hospitaller idea 6: Scourge of the Corsairs
  • Malaccan traditions
  • Gutnish idea 6: Gutnish Merchant Navy
  • Karelian idea 5: Baltic Shipyards
  • Cypriot ambition
  • Maritime-Expansion: Naval Infrastructure
  • Kilwan traditions
  • Moroccan traditions
  • Sulawesi traditions
  • Exploration idea 7: Global Empire
  • Alaskan idea 6: Alaskan Navy
  • Berber idea 1: Barbary Pirates
  • Candarid idea 6: Sinop Shipyard
  • Couronian idea 5: Couronian Colonization
  • Dalmatian idea 6: The Independent Arsenal
  • Estonian idea 2: Baltic Ties
  • Genoese idea 6: Setup the Office of Grand Admiral
  • Hadramhi idea 5: Sailors of the Indian Ocean
  • Hormuz idea 7: Hormuzi Naval Expansion
  • Ionian idea 5: Naval Expansion
  • Kono idea 1: Shugo of Iyo
  • Leonese idea 5: Expand the Leonese Navy
  • Orissan idea 7: Heritage of the Sadhabas
  • Pomeranian idea 7: German Navy
  • So idea 6: Port Maintenance
  • Somalian idea 6: Indian Merchants
  • Spanish idea 3: Treasure Fleet
  • Sumatran idea 7: Rule of The Sea
  • Venetian idea 1: Venetian Arsenal
  • West Indies idea 7: Colonial Legacy
  • Breton ambition
  • Cham ambition
  • Hamburger ambition
  • Malagasy ambition
  • Tunisian ambition
  • Corsican traditions
  • Navarran traditions
  • Sardinian traditions
  • Mogadishan idea 6: Horn of Africa
  • Naxian idea 1: Maritime State
  • Ragusan idea 4: Ragusan Arsenal
  • Sligonian idea 6: Sligo's Naval Ambition
  • Al-Haasa ambition
  • Croatian traditions
  • Maritime-Defensive: The Fleet is our Wooden Wall
  • Aragonese idea 2: Protection of the Coastlines
  • Provençal idea 6: Toulon Dockyard
  • Samoan idea 2: Fa'a Samoa
  • Horde-Maritime: Riverine Navy
  • +10%
if the Statists are in power
  • +30%
if you are a March nation
  • +20%
Trading in bonus: Naval supplies
  • +40%
Being the revolution target
  • +50%
Being the Pirate Republic

But there are other bonuses which are not from Ideas, Policies or government

  • +0.1
per development (only coastal provinces)
  • +2
per Shipyard (only coastal provinces)
  • +4
per Grand shipyard (only coastal provinces, replace previous Shipyard)
  • +0.5
per provinces in a trade company (only coastal provinces)
  • +5
per Admiralty in a trade company (only for each per trade company)
  • +10
per large (10 or more provinces) colonial nation


Each ship costs ducats to upkeep every month. By class, the base ship maintenance depends on the type of ship and is proportional to the cost to build the ship along with a defined ship maintenance factor, based on ship type. This cost in turn is then multiplied by global cost modifiers to obtain the total cost per month for that specific ship.

Naval maintenance can be computed as follows:




In this case, the game truncates all digits to the right of the third digit after the decimal point. For example:


The base build costs and ship maintenance factors are given here:

Ship Class Base Cost Maintenance Factor monthly maintenance without any modifiers
  Heavy ships 50 0.10 0.4
  Light ships 20 0.03 0.04
  Galleys 10 0.04 0.03
  Transport 12 0.04 0.036
  • Being over naval force limit will multiply the maintenance cost of ships by the force limit proportion. For example, if a country has 10 ships on a force limit of 5, maintenance is doubled.
  • Practically speaking, for a homogeneous fleet, the marginal maintenance of the first ship built or captured above the naval force limit is about 2* normal. For example, being at 100% of the force limit will result in the next ship adding about 200% of its normal maintenance, with this multiplier increasing by 2x per multiple of the force limit reached.
  • Light Ships suffer the penalty to their build cost as well, which squares the effect on maintenance cost. For example, being at 150% of the force limit with all Light Ships will result in navy maintenance being 225% of normal. In this case, the marginal maintenance is about 3* the force limit proportion squared. For example, being at 150% of the force limit with all Light Ships will result in the next light ship adding about 675% of its normal maintenance.
  • Unlike land units, the tech modifier to Naval maintenance stacks multiplicatively with other modifiers. Thus, reductions to Naval Maintenance keep their strength better throughout the game than their land counterpart.
  • For a homogeneous fleet, the marginal maintenance of each ship is about twice the force limit proportion. For example, being at 150% of the force limit will result in the next ship adding about 300% of its normal maintenance.

  Traditions Ideas Bonuses Policies
  • Omani traditions
  • Eastern Algonquian idea 4: Fishing Habits
  • Luzon idea 1: Barangay State
  • Malayan Sultanate idea 5: Trading Fleets
  • Mindanao idea 4: Moro Sailors
  • Tongan idea 6: Ancient Tongan Craftsmanship
  • Genoese ambition
  • Javan ambition
  • Mahri ambition
  • Rûmi idea 5: Sultan al-Bahrayn
  • Gelre traditions
  • Siddi idea 7: Expansion of the Navy
  • Provençal idea 6: Toulon Dockyard

Additionally, raising war taxes gives a -15% modifier.


"Mothballing" a fleet, thus lowering the maintenance cost of a fleet to the minimum (50%) for the specific fleet. Ship condition and  sailors will decrease at 5% per month down to a minimum of 25% while the fleet is mothballed, and will be repaired back to full strength at the normal rate (10% per month by default) when returned to active service, which can be done at any time. Mothballed fleets cannot be moved and can only be combined with other mothballed fleets, though they can be split into smaller fleets as usual.


While quantity is an important factor in naval warfare, quality could be considered even more crucial. Because of the limited amount of ships that can fire at the same time in a naval battle, ships that hit harder will quickly take the upper hand in a fight

Several idea groups can be taken to progressively improve a navy's performance on the battlefield. Additionally, some nations get specific bonuses resembling the strength their navy had in actual history.

General improvementsEdit

The main improvement of a fleet is performed by replacing or upgrading naval units as diplomatic technology improves. New ship types are unlocked at several diplomatic technology levels. Ships will have to be rebuilt or upgraded in order for them to receive the bonuses from a newer ship type. In addition to ship types, diplomatic technology also improves naval morale at certain levels.

Combat ability improvementsEdit

Combat ability is a value that is multiplied with the units' damage dealt (both for casualties and morale), but only for the specified type of unit.

Heavy ship combat ability

  Traditions Ideas Bonuses Policies
  • Naval idea 6: Oak Forests for Ships
  • British traditions
  • Butuan idea 6: Protect the Coastlines
  • Date idea 5: Red Seal Ships
  • English idea 1: A Royal Navy
  • Hanseatic idea 4: Adler von Lubeck
  • Majapahit idea 6: The Majapahit Armada
  • Spanish idea 4: A Spanish Armada
  • Alaskan ambition
  • Genevan ambition
  • Innovative-Maritime: New Naval Tactics

Light ship combat ability

  Traditions Ideas Bonuses Policies
  • Veronese ambition
  • Hawaiian traditions
  • Alaskan traditions
  • Cham traditions
  • Eora traditions
  • Ferraran traditions
  • Icelandic idea 4: Armed Merchants
  • Moluccan idea 6: Alliance with the Papuans
  • Arakanese ambition
  • Holstein ambition
  • Maritime-Plutocratic: The Protected Shipping Lanes Act
  • Fijian traditions
  • Hamburger traditions
  • Pattani traditions
  • Somali idea 6: Corsairs of the Red Sea
  • Sumatran idea 3: Spice Pirates

Galley combat ability

  Traditions Ideas Bonuses Policies
  • Naval idea 2: Improved Rams
  • Malayan idea 2: Advanced Galley Warfare
  • Venetian ambition
  • Aragonese traditions
  • Barbary Corsair traditions
  • Cebu traditions
  • Hosokawa traditions
  • Ionian traditions
  • Tunisian traditions
  • Berber idea 7: The Brothers Barbarossa
  • Bruneian idea 1: Galley Fleet
  • Cypriot idea 6: Repel the Corsairs
  • Italian idea 3: Mare Nostrum
  • Kitabatake idea 4: Kuki Suigin
  • Knights Hospitaller idea 4: Reconquista of the Sea
  • Moroccan idea 4: Defend the Coastline
  • Kono idea 5: Rule Over the Inland Sea
  • Somalian ambitions
  • Maritime-Quantity: Streamlined Galley Production
  • Naxian idea 1: Maritime State
  • So idea 2: Wakou Tradition

  Morale improvementsEdit

Naval morale indicates how long a fleet can keep fighting. It is increased by the following ideas: Naval morale

  Traditions Ideas Bonuses Policies
  • Alaskan traditions
  • British traditions
  • Genoese idea 2: The Lessons of Chioggia
  • Kono idea 3: Oyamazumi Shrine
  • Livonian idea 6: Naval Professionalism
  • Norwegian idea 3: Natural Seamanship
  • Scandinavian idea 4: Norwegian Marines
  • So idea 3: Fight for Tsushima
  • Luzon ambition
  • Quality-Maritime: The Organized Marines Act
  • Omani traditions
  • Acehnese/Pasai idea 4: Military Adventures
  • Bregenzer idea 7: The Lake Constance Navy
  • Bruneian idea 6: Naval Prowess
  • Chiba idea 7: Naval Reform
  • Corsican idea 2: The Battle of Meloria
  • Danish idea 5: Naval Heroes
  • Eora idea 1: Eora Lifestyle
  • Madyas idea 2: Legacy of Panai
  • Malayan idea 4: Chart the Isles
  • Manx idea 4: Mann and the Isles
  • Norse idea 2: Norse Seamen
  • Ouchi idea 3: Protect Against Piracy
  • Sicilian idea 6: The Grand Navy
  • Dalmatian ambition
  • Mogadishan ambition
  • Ragusan ambition
  • Siddi ambition
  • Candarid traditions
  • Naval idea 7: Superior Seamanship
  • Quality idea 5: Naval Drill
  • Eastern Algonquian idea 5: Whale Hunters
  • Piratical idea 5: Elected Quartermasters
  • Portuguese idea 1: Legacy of the Navigator
  • Exploration-Defensive: The Naval Secrecy Act
  • Religious-Maritime: Chaplains of the Fleet

  Morale recovery improvementsEdit

Naval morale recovery

  Traditions Ideas Bonuses Policies
  • Palembang idea 6: Through the Monsoon
  • Humanist-Naval: The Naval Inspection Act
  • Naval-Innovative: The Nautical Education Act
  • Religious-Maritime: Chaplains of the Fleet

Admiral.png Naval leaderEdit

Fleets can be led by either an admiral or an explorer. The only combat difference between the two is that the admiral will get more pips, on average, when he's created. Having a naval leader in a battle greatly improves the combat ability of the fleet. The skills of the naval leader can be influenced by the following ideas:

Naval leader fire

  Traditions Ideas Bonuses Policies
  • Dutch idea 4: Instructie voor de Admiraliteiten
  • Naval idea 3: Naval Cadets
  • Ferraran idea 7: The Ferraran Arsenal
  • Norman idea 7: Great Commanders
  • Tunisian idea 5: Board of Captains
  • Corsican ambition
  • Madyas ambition
  • Naval-Innovative: The Nautical Education Act

Naval leader shock

  Traditions Ideas Bonuses Policies
  • Naval idea 1: Boarding Parties
  • Danish idea 5: Naval Heroes
  • Madyas idea 4: Masters of Maritime Warfare
  • Norse idea 3: A Wall of Shields for the King
  • Naval-Religious: Zealous Captains

Naval leader maneuver

  Traditions Ideas Bonuses Policies
  • Madyas traditions
  • British idea 7: Britannia Rules the Waves
  • Hawaiian idea 7: Legendary Voyagers
  • Mahri idea 4: Pilots of the Arabian Sea
  • Mogadishan idea 2: Somali sailors
  • Omani idea 6: Skilled Captains
  • Somalian idea 4: Zeila and Berbera
  • Spanish idea 4: A Spanish Armada
  • Swahili idea 2: Monsoon Season
  • Innovative-Maritime: New Naval Tactics
  • Maritime-Offensive: Hold the Weather Gauge

Navy traditionEdit

Main article: Military tradition#Navy tradition

Navy tradition is a value that indicates the naval experience of a nation and greatly improves a nation's ability to rule the seas. Navy tradition is gained by ideas, naval combat, exploring and protecting trade. 100 navy tradition gives the following bonuses, linearly increasing from 0 to 100:

At 100:

  +10%.00 Recover navy morale speed
  +25%.00 Morale of navies
  +100%.00 Trade steering
  +25%.00 Privateer efficiency
  +100%.00 Blockade efficiency
  +0.10% Trade faction influence
  +0.10% The traders influence
  +20%.00 Sailor recovery speed
  +5%.00 Burghers loyalty equilibrium
  +5%.00 Vaishyas loyalty equilibrium

Supply, attrition and repairEdit

Supply rangeEdit

The supply range is a key factor in determining where light ships can be sent to protect trade, and it determines whether ships suffer attrition or not. Base supply range is 150. It can be extended by the trade range modifiers below:

  Traditions Ideas Bonuses Policies
  • Ryukyuan idea 4: Maritime Commercialism
  • Swahili traditions
  • Maritime idea 1: Merchant Traditions
  • Trade idea 3: Merchant Adventures
  • Kilwan idea 1: Kilwan Latitude Staves
  • Trading City idea 6: City of Great Reach
  • Gujarat Sultanate idea 2: Jain Connections
  • Gujarati Princedom idea 7: Extend Trade Routes to Africa
  • Horn of African idea 2: The Land of Punt Legend
  • Kono idea 6: Trade With Continental Asia
  • Malabari idea 1: Merchants of Southern India
  • Mesoamerican idea 7: Obsidian and Jade
  • Mogadishan idea 1: Indian Ocean Trade
  • South Indian idea 1: Merchants of Southern India
  • Sumatran traditions
  • Traditions of The Hansa
  • Evenk idea 2: Reindeer Herding
  • Indigenous-Trade: Commercial Tribes
  • Dutch idea 2: Dutch Trading Spirit
  • Mamluk idea 1: Red Sea Trade
  • West Indies idea 4: The American Trade Hub
  • Supply range cannot be extended by flat trade range modifier. Technology, for instance, only increases the trade range by a fixed number and therefor does not influence the supply range.* A good way to arrange for a favorable supply range is by gaining fleet basing rights from a nation in the vicinity of where attrition is undesired and/or ship repairs are needed.


Navies suffer from attrition from being in the open seas or being far away from port too long. A navy does not suffer attrition if it is within naval supply range' and in a coastal zone (open sea always causes attrition). Sea zones that contain a dockable port also count as home waters and will never cause attrition, even if it is outside naval supply range.

Having your Navy in a Sea Tile adjacent to a Province that has either the Naval Battery Building or the Cartagena de Indias Fort System Monument while being at war with the province owner, will cause attrition, even if you normally wouldnt suffer attrition in that tile.

Attrition damage is governed by the following rules:

  • Monthly attrition damage equal to the listed attrition percentage will be applied to all ships in a fleet at the beginning of each month.
  • Movement into any sea province has a 50% chance to cause any ship to take attrition damage unless they immediately engage in combat. Be aware that two fleets will only engage in combat if at least one of them is stationary.
  • Explorers leading a fleet give a chance to all ships under their command to avoid any source of attrition damage. This allows fleets led by explorers to travel much farther than normal. The chance of avoidance appears to improve with the health of each ship, and decreases with the amount of attrition damage that must be avoided. Fleets lead by explorers in coastal seas have a particularly high chance of avoiding attrition damage.
  • In   El Dorado, a fleet engaged in regional exploration (exploring water or coast) will not suffer any attrition, regardless of its location and time at sea. A fleet on global circumnavigation mission will have attrition as usual. However, the fleet on exploration mission will not receive any further commands until it returns to a home port.

The following factors influence naval attrition:

  Traditions Ideas Bonuses Policies
  • Berber traditions
  • Central Algonquian traditions
  • Eastern Algonquian traditions
  • Quality idea 6: Copper Bottoms
  • Fijian traditions
  • Base attrition: +1%
  • Time at sea: +1% per month, eliminated after diplomatic tech level 22 is discovered
  • Open sea: +5%
  • Adjacent Province of War enemy has Naval Battery : +5%
  • Adjacent Province of War enemy has Cartagena de Indias Fort System Monument at Level 2 : +5%
  • Adjacent Province of War enemy has Cartagena de Indias Fort System Monument at Level 3 : +10%
  • Naval leader's maneuver rating: 1% less Attrition per point

AI navies do not take attrition damage as the AI is unable to adequately manage it. Internal game rules instead limit how far the AI can send their fleet for exploration or combat.

Ship repairEdit

Ships which have sustained damage (i.e. their condition is lower than 100%) will automatically repair up to 100% condition when docked in any province. Any number of ships can be repaired by a single port at once with no penalty to repair speed.

Importantly, since damaged ships operate at a reduced sailor capacity, repaired ships will consume additional sailors from the sailor pool. This means that if you do not have any sailors left in your pool then no ships can be repaired until you do - in such a case only the number of sailors recruited during that month will be applied to repair ships that you have stationed in a port. Therefore repairs will creep up only at your monthly recruitment rate.

Note that repair speeds are faster in a port where a shipyard (+25% ship repair) and grand shipyard (+50% ship repair) are present.

Automatic docking for repairsEdit

Once a fleet's average morale value has been reduced enough, a fleet will attempt automatic docking to a nearby port for repair and morale recovery. In the mission settings, a fleet's repair threshold can be set, determining how much damage a fleet can take before going to a port for repairs.

Rate of repairEdit

Ships will automatically be repaired on the first day of each month if they are docked in port. The repair amount is 10%[4] at full naval maintenance, and will decrease linearly to 0% at minimum naval maintenance. Repair speed is affected by certain modifiers.

Countrywide modifiers:

  Traditions Ideas Bonuses Policies
  • Maritime idea 3: Sheltered Ports

Local modifiers:

+50% for having a   grand shipyard

Repair at seaEdit

The maritime idea group finisher gives ships the ability to be repaired in coastal sea zones within supply range. The repair rate is 6% of ship hull per month, unaffected by modifiers.


  1. 1.0 1.1 See in /Europa Universalis IV/common/defines.lua.
  2. 2.0 2.1 2.2 2.3 See Naval units for the sailor cost for each ship model.
  3. 3.0 3.1 3.2 3.3 See in /Europa Universalis IV/common/static_modifiers/00_static_modifiers.txt (Static modifiers).
  4. See in /Europa Universalis IV/common/defines.lua: MONTHLY_REPAIR = 0.1

Ideas and Policies Idea groupsNational ideasPolicies
Ages and Institutions AgesInstitutions
Innovativeness and Technology InnovativenessTechnology