Mar 27, 2026
View on Steam↗HOI IV - Open Beta Update 01
4/5 Significant
Submarine detection formula reworked and minimum naval hit chance slashed from 2% to 0.5% to reduce torpedo lethality, alongside massive resource and manpower cost reductions for most ship hulls.
Key Changes
- 1Submarine detection formula reworked to fix excessive losses
- 2Minimum naval hit chance reduced from 2% to 0.5%, nerfing torpedoes
- 3Resource costs removed from most naval modules (guns, armor, hangars)
- 4Supply consumption significantly reduced for Carriers, Battleships, and Cruisers
- 5Manpower requirements reduced for nearly all ship hull types
- 6Sea zone dominance threshold lowered from 66% to 60%
- 7Naval range increased for all Destroyer tiers and Coastal Defense ships
- 8IC cost and visibility reductions for Panzerschiff and Coastal Defense ships
- 9Naval XP gain rates increased for most mission types
- 10Steel and Chromium costs adjusted for almost every ship hull tier
All Changes
⚓Naval Gameplay(5)
- changeSubmarines: Reworked submarine detection formula to prevent submarines from being revealed too frequently while maintaining balanced detection rates.
- newSubmarines: Added three new defines for modders: SUBMARINE_BASE_STEALTH_VALUE, SUBMARINE_REVEAL_DETECTION_MULTIPLIER, and SUBMARINE_REVEAL_TORPEDO_FIRING_DETECTION_MULTIPLIER.
- nerfTorpedoes: Reduced minimum naval hit chance from 2% to 0.5% to reduce overall naval combat lethality and nerf Torpedo Destroyers.
- buffNaval Missions: Increased Naval XP gain ratio for Patrol, Convoy Raiding, Convoy Escort, Mines Planting, and Mines Sweeping missions to 0.2.
- buffStrike Force: Increased Naval XP gain ratio for Strike Force missions to 0.5.
🚢Ship Hulls(17)
- buffPanzerschiff: Reduced Panzerschiff Hull IC cost from 3000 to 2800 and Surface Visibility from 20 to 18.
- buffCoastal Defence Ship: Reduced Coastal Defence Ship Surface Visibility from 18 to 16.
- buffEarly Destroyer: Increased Early Destroyer naval range from 1500 km to 2000 km.
- buffBasic Destroyer: Increased Basic Destroyer naval range from 1800 km to 2500 km.
- buffImproved Destroyer: Increased Improved Destroyer naval range from 2000 km to 3000 km.
- buffAdvanced Destroyer: Increased Advanced Destroyer naval range from 2500 km to 3500 km.
- nerfImproved Cruiser: Reduced Improved Cruiser naval range from 4000 km to 3500 km.
- nerfAdvanced Cruiser: Reduced Advanced Cruiser naval range from 4500 km to 4000 km.
- nerfTorpedo Cruiser: Reduced Torpedo Cruiser naval range from 4000 km to 3500 km.
- buffCoastal Defense Ship: Increased Coastal Defense Ship naval range from 1500 km to 2000 km and reduced IC cost from 3500 to 1500.
- buffPre-Dreadnaught Hull: Increased Pre-Dreadnaught Hull naval range from 2250 km to 2500 km.
- buffModern Heavy Hull: Reduced Modern Heavy Hull IC cost from 4000 to 3600.
- nerfCruiser Carrier Conversion: Reduced Cruiser Carrier Conversion naval range from 4000 km to 3000 km.
- nerfBattleship Carrier Conversion: Reduced Battleship Carrier Conversion naval range from 4000 km to 3000 km.
- buffBasic Carrier: Increased Basic Carrier naval range from 3000 km to 3500 km.
- buffImproved Carrier: Increased Improved Carrier naval range from 4000 km to 4250 km.
- buffEscort Carrier: Reduced Escort Carrier Hull IC cost from 1500 to 1250.
⛏️Resource Costs(24)
- buffNaval Modules: Removed resource costs from most naval modules including guns, deck armor, and hangar decks.
- buffBasic Cruiser Hull: Reduced Steel cost for Basic Cruiser Hull from 3 to 2.
- buffImproved Cruiser Hull: Reduced Chromium cost for Improved Cruiser Hull from 1 to 0.
- buffAdvanced Cruiser Hull: Reduced Steel cost for Advanced Cruiser Hull from 4 to 3.
- buffBasic Carrier Ship Hull: Reduced Steel cost for Basic Carrier Ship Hull from 5 to 4.
- buffImproved Carrier Ship Hull: Reduced Steel cost for Improved Carrier Ship Hull from 6 to 5.
- buffAdvanced Carrier Ship Hull: Reduced Steel cost for Advanced Carrier Ship Hull from 7 to 6.
- buffModern Carrier Ship Hull: Reduced Steel cost for Modern Carrier Ship Hull from 8 to 6.
- buffIce Carrier Ship Hull: Reduced Steel cost for Ice Carrier Ship Hull from 10 to 8.
- buffBasic Heavy Ship Hull: Reduced Steel cost for Basic Heavy Ship Hull from 4 to 3.
- buffAdvanced Heavy Ship Hull: Reduced Steel cost for Advanced Heavy Ship Hull from 5 to 4.
- buffSuper Heavy Ship Hull: Reduced Chromium cost for Super Heavy Ship Hull from 3 to 2.
- buffModern Heavy Ship Hull: Reduced Modern Heavy Ship Hull costs: Steel from 6 to 5 and Chromium from 4 to 2.
- buffCruiser Armor Scheme: Reduced Cruiser Armor Scheme Steel costs (0/0/1/1) and Chromium costs (0/0/0/1).
- buffBattleship Armor Scheme: Reduced Battleship Armor Scheme Steel costs to 1/1/1.
- nerfSubmarine Carrier Hull: Increased Submarine Carrier Hull Steel cost from 3 to 4.
- buffAdvanced Destroyer Hull: Reduced Advanced Destroyer Hull Steel cost from 4 to 3.
- nerfEarly Cruiser Hull: Increased Early Cruiser Hull Steel cost from 1 to 2.
- nerfTorpedo Cruiser Hull: Increased Torpedo Cruiser Hull Steel cost from 2 to 3.
- nerfPanzerschiff Hull: Increased Panzerschiff Hull costs to 3 Steel and 1 Chromium.
- buffCoastal Defense Ship Hull: Reduced Coastal Defense Ship Hull Steel cost from 3 to 2.
- changePre-Drednought Ship Hull: Changed Pre-Drednought Ship Hull cost from 1 Steel + 1 Chromium to 2 Steel.
- nerfEarly Heavy Ship Hull: Increased Early Heavy Ship Hull Steel cost from 1 to 3.
- nerfEscort Carrier Ship Hull: Increased Escort Carrier Ship Hull Steel cost from 2 to 3.
📦Supply & Manpower(13)
- buffCarriers: Reduced supply consumption for Carriers from 1.2 to 0.8.
- buffBattleships: Reduced supply consumption for Battleships from 0.8 to 0.56.
- buffBattlecruisers: Reduced supply consumption for Battlecruisers from 0.48 to 0.32.
- buffHeavy Cruisers: Reduced supply consumption for Heavy Cruisers from 0.4 to 0.24.
- buffDestroyers: Reduced service manpower for Basic Destroyer (300), Improved Destroyer (350), and Advanced Destroyer (400).
- buffCruisers: Reduced service manpower for Improved Cruiser (1000), Advanced Cruiser (1200), and Torpedo Cruiser (900).
- buffPanzerschiff: Reduced service manpower for Panzerschiff from 1800 to 1200.
- buffCoastal Defense Ship: Reduced service manpower for Coastal Defense Ship from 1800 to 1000.
- buffHeavy Hulls: Reduced service manpower for Basic Heavy Hull (4300), Improved Heavy Hull (4650), Advanced Heavy Hull (5000), and Modern Heavy Hull (5000).
- buffBattleship Carrier Conversion: Reduced service manpower for Battleship Carrier Conversion from 5000 to 3500.
- buffCarriers: Reduced service manpower for Basic Carrier (4000), Improved Carrier (4500), Advanced Carrier (5000), and Modern Carrier (6000).
- buffEscort Carrier: Reduced service manpower for Escort Carrier from 2500 to 1500.
- buffSuper Heavy Hull: Reduced service manpower for Super Heavy Hull from 9000 to 7000.
🖥️UI/UX(1)
- changeSea Zone Dominance: Updated tooltip to reflect that the control ratio required for sea zone dominance is now 60% (down from 66%).
Summary
This Open Beta update for Hearts of Iron IV focuses on a significant overhaul of naval balance. Key changes include a reworked submarine detection formula to prevent excessive losses and a reduction in minimum hit chance to curb the dominance of Torpedo Destroyers. The update also introduces sweeping reductions in resource costs, manpower requirements, and supply consumption across nearly all ship classes to encourage more diverse fleet compositions and sustainable naval warfare.