Combat/Overweight Penalty and Fit Gun Bonus

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The "hidden fit bonus" mechanic refers to some ships receiving bonuses or penalties when equipping certain equipment, depending on if the equipment "fits" the class or not.

  • This almost exclusively refers to main guns, where each class of ship is engineered to carry up to certain gun calibers, and so, equipping gun turrets of the right caliber or lower will imply an accuracy bonus, whereas using larger calibers will result in some overweight penalties.
  • So far, all fits involve Accuracy Accuracy, and some also affect Firepower Firepower (excluding #Arctic Map Bonuses unic case).
    • Accuracy Accuracy bonuses work like regular visible Accuracy stat, see here for more information.
    • Firepower Firepower bonuses are "pre-cap",
  • Not to be confused with visible Equipment Bonuses.

As hidden bonuses are unaffected by morale or fleet types (e.g. combined fleets), it can be interesting to utilize those fit bonuses as much as possible.

How much bonus/penalty a ship receives, depends on:

  • The ship class, larger classes being able to carry larger equipment,
  • If the ship is married or not, married girls having better fits,
  • The gun size (caliber and quantity per turret), the larger ones being the most constraining.
  • Some other less frequent factors:
    • The ship's remodel,
    • The ship's speed,
    • Whether it is a day or night battle.

Battleships (FBB/BB/BBV) Bonuses

Battleships receive accuracy   bonuses if the guns are fit and penalties if it is overweight [3].

Table Explainer

When equiping   "Large Caliber Main Guns" on a FBB/BB/BBV, the resulting accuracy bonus/penalty is:

Fit Formula
[math]\displaystyle{ \text{ACC}_\text{bonus} = \sum^{\text{All Groups} } C_{Group} \times \sqrt{N_{Group} } \times M }[/math]
With
  • [math]\displaystyle{ \text{All Groups} }[/math] the gun groups and sub-groups defined in the following tables.
  • [math]\displaystyle{ C_{Group} }[/math] the accuracy modifier of the group, given in the following table.
    • When a ship has additional bonuses to a group compared to her type, this bonus is summed as a separate "Group".
  • [math]\displaystyle{ N_{Group} }[/math] the number of guns of a same group.
  • [math]\displaystyle{ M }[/math] the Marriage bonus of 0.6 when applicable, 1 else.
    • This bonus is applied only for Groups marked by footnote [1],
    • When applied, this bonus is applied in all situations, with penalties being reduced by 0.6, as well as bonuses being reduced by 0.6.
    • For Iowa-class with the USN 16" Mk7 guns, M may be better, the observed bonu being [math]\displaystyle{ \text{ACC}_\text{bonus} = 6 \times \sqrt{N_{16inch Mk.7}} + 12 \times \sqrt{N_{16inch Mk.7 GFCS}} }[/math].
Notes
  • For BB only: if the base maximum HP   (unmodified & before marriage) is superior to 92, set fit bonuses are set to 0.
  • Do note that speed modding ships (to Fast+) has been observed to worsen the penalties on certain ships.
Examples

Kongou Kai Ni equipped with 2 IJN 35.6cm Twin K2 :

  • [math]\displaystyle{ \text{ACC}_\text{bonus} = C_{35.6 cm FBB} \times \sqrt{N_{35.6 cm}} + C_{35.6 cm Kongou-class} \times \sqrt{N_{35.6 cm}} = ( 4 + 3 ) \times \sqrt{2} = +9.90 }[/math]
  • This bonus stays the same when married, as no M multiplier is applied in this case.


Nagato Kai Ni equiped with 1 IJN 41cm Twin  and 1 IJN 51cm Twin Proto :

  • [math]\displaystyle{ \text{ACC}_\text{bonus} = C_{41 cm BB} \times \sqrt{N_{41 cm}} + C_{IJN 41cm Twin Nagato Kai Ni} \times \sqrt{N_{IJN 41cm Twin}} + C_{51cm} \times \sqrt{N_{51cm}} = ( 2 + 4 - 5 ) \times \sqrt{1} = +1.00 }[/math]
  • If Nagato Kai Ni is married, the M multiplier is applied to the -5 only in this case.


Musashi Kai Ni equiped with 1 IJN 51cm Twin  and 1 IJN 51cm Triple Proto 

  • [math]\displaystyle{ \text{ACC}_\text{bonus} = C_{51 cm Musashi Kai Ni} \times \sqrt{N_{51 cm}} = 0 \times \sqrt{2} = +0.00 }[/math]
  • Musashi Kai Ni has 99 bases  , and so has bonuses set to ZERO for those guns.


Yamato Kai Ni Juu equiped with 1 IJN 46cm Triple  and 1 IJN 51cm Triple Proto 

  • [math]\displaystyle{ \text{ACC}_\text{bonus} = C_{46 cm Triple Yamato-class} \times \sqrt{N_{46 cm Triple}} + C_{46/51 cm Yamato Kai Ni Juu} \times \sqrt{N_{46/51 cm}} = 7 \times \sqrt{1} + (-8) \times \sqrt{2} = -4.31 }[/math]
  • If Yamato Kai Ni Juu is married, the M multiplier is applied to the -8 only in this case.

Gun Groups

  Large Caliber Main Guns Groups
Gun Groups Guns
Sov 30.5 cm [1] Sov 30.5cm Triple 
Sov 30.5cm Triple K 
RM 30.5-32 cm [1] RM 305mm/46 Twin 
RM 305mm/46 Triple 
RM 320mm/44 Twin 
RM 320mm/44 Triple 
35.6 cm IJN 35.6cm Twin 
IJN 35.6cm Twin Dazzle 
IJN 35.6cm Twin K 
IJN 35.6cm Twin K2 
IJN 35.6cm Twin K3 Dazzle 
IJN 35.6cm Twin K4 
IJN 35.6cm Triple Proto 
IJN 35.6cm Triple K Dazzle 
KMS 38cm Twin 
KMS 38cm Twin K 
RN 38.1cm Twin  [1]
RN 38.1cm Twin K  [1]
USN 14" Twin  [1]
USN 14" Triple  [1]
FR 38 cm FR 38cm Quad 
FR 38cm Quad K 
FR 38cm Quad K2 
RM 381 mm RM 381mm/50 Triple 
RM 381mm/50 Triple K 
41 cm IJN 41cm Twin 
IJN 41cm Twin K2 
IJN 41cm Triple Proto 
IJN 41cm Triple K 
IJN 41cm Triple K2 
RN 16" Triple 
RN 16" Triple + AFCT 
RN 16" Triple + FCR 
USN 16" MkI Twin 
USN 16" MkV Twin 
USN 16" MkVIII Twin 
USN 16" Triple Mk6 
USN 16" Triple Mk6 + GFCS 
USN 16" Triple Mk6 M2 
USN 16" Mk7 USN 16" Triple Mk7 
USN 16" Triple Mk7 + GFCS 
46 cm [2] Twin IJN 46cm Twin Proto 
Triple IJN 46cm Triple 
Triple K IJN 46cm Triple K  [1]
51 cm IJN 51cm Twin Proto 
IJN 51cm Twin 
IJN 51cm Triple Proto 
15.5 cm Sec [3] IJN 15.5cm Triple Sec 
IJN 15.5cm Triple Sec K 
IJN 15.5cm Triple Sec K2 
  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 There is not enough data yet to determine exact category of those guns.
  2. The 46 cm are not counted as a single group as several cases show disparities.
  3. Other secondary guns may also have some hidden fits, but are unmapped yet.

Bonus Groups

Type Class Ship Sov 30.5 cm RM 30.5-32 cm 35.6 cm FR 38 cm RM 381 mm 41 cm USN 16" Mk7 46 cm Twin Proto  46 cm Triple  46 cm Triple K  51 cm 15.5 cm Sec
other
35.6 cm
RN 38.1 cm 
 
IJN 41 cm Twin  other
41 cm
Mk7  Mk7 + GFCS 
FBB Base Bonus ? ? 4 0 -2 [1] -5 [1] -5 [1] -7 [1] -10 [1] -10 [1] N/A 0
FBB
Additional
Bonuses
Gangut-class - 12 -4 [1] N/A
Conte di Cavour-class Kai/Nuovo Kai/Nuovo 14
Kongou-class - 3
Bismarck-class - 3 [1]
Vittorio Veneto-class -
Richelieu-class - 2 -2 [1]
North Carolina-class -
South Dakota-class -
Iowa-class - 7 [1] 14 [1]
BB Base Bonus ? ? 2 0 2 [1] 2 0 -3 [1] -7 [1] ? [1] N/A 0
BB
Additional
Bonuses
Conte di Cavour-class base base N/A
Fusou-class base base
Ise-class base base
Nagato-class base/Kai/Ni 2 -5 [1]
Nagato Kai Ni  4 3
Nevada-class - N/A
Colorado-class -
Queen Elizabeth-class - 2?
Nelson-class -
Nelson Kai [2] 0
BBV Base Bonus ? ? 4 0 2 [1] 2 0 -3 [1] -7 [1] -7 [1] N/A 0
BBV
Additional
Bonuses
Fusou-class Kai/Ni Kai/Ni N/A
Ise-class Kai/Ni Kai/Ni
Yamato-class Base Bonus[3] 3 3 7 2
BB Yamato-class Base/Kai/Ni[2] 0
FBB Yamato Kai Ni  -10 [1]
BBV Yamato Kai Ni Juu [4] -5 [1] -8 [1][5]
  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 In those cases ONLY, the Marriage multiplier M (0.6x) is applied when married.
  2. 2.0 2.1 For BB only: if the base maximum HP (unmodified & before marriage) is > 92, set fit bonuses are set to 0.
  3. For all Yamato-class ships, the bonuses are applied in addition to other base types (FBB/BB/BBV) bonuses, including the 92+ HP rule for BB.
  4. Yamato Kai Ni Juu specified bonuses override the base BBV bonuses.
  5. In this case, the "46 cm Triple", "46 cm Triple K", and "51 cm" groups are counted as one.

Sources: [4] [5]

Cruiser Bonuses

    Medium Caliber Main Guns Groups
Gun Groups Guns
A 14cm Single 
14cm Twin 
14cm Twin Kai 
14cm Twin Kai 2 [1]
B 15.2cm Twin 
15.2cm Twin Kai 
15.2cm Twin Kai 2 
Bofors 15.2cm Twin Mod 1930 
Bofors 15cm Twin Mk9 Mod 1938 
Bofors 15cm Twin Mk9 Kai + Single Mk10 Kai Mod 1938 

6" Twin MkXXI 

C 15.5cm Triple 
15.5cm Triple Kai 
D 6" Triple Mk16 
6" Triple Mk16 mod2 
6" Triple MkXXIII 

152mm/55 Triple 
152mm/55 Triple Kai 

E 5" Twin CD 
GFCS + 5" Twin CD 
F 20.3cm Twin 
20.3cm N°2 Twin 
20.3cm N°3 Twin 
20.3cm N°4 Twin proto [2]
SKC34 20.3cm Twin 
203mm/53 Twin 
G 8" Triple Mk9 
8" Triple Mk9 mod2 
  1. This gun bonuses are unclear [1][2]
  2. There is not enough data yet to determine exact category of those guns.
Notes
  • Future Medium Guns may fall in one of those categories based on similarities like caliber and number of guns.
  • Groups A, B, C, D, and E are "Light Cruiser Guns", and Groups F and G are "Heavy Cruiser Gun".

Light Cruisers (CL/CLT/CT)

Accuracy   bonuses for Light Cruisers (CL), Torpedo Cruisers (CLT), and Training Cruisers (CT).

Ships Guns group[1]   Accuracy bonus/penalty
1st Gun 2nd Gun Unmarried Married
Default to
every CL(T)/CT
- - 0 0
A/B A/B 0 2
C C -5? -1?
D D -6 -3.6
E E
F F
F - -3 -1.8
G G -22 -17.6
15.2cm Single Secondary  +4N ?
Agano-class B - 5 7
B B 6 8
F F -8 -6
Ooyodo C C -2 -1.2
F F -10 -8
Atlanta-class E E 0 3
Abyssals - - 0[2] -
Any Medium Gun - -3[3] -
  • There is not enough data to pin down the exact fit accuracy formula.
  • Other gun combinations fits cannot be extrapolated yet.
  • There are known tests where the fit bonuses do not scale linearly with the number of guns.


Firepower   bonuses for Light Cruisers (CL), Torpedo Cruisers (CLT), and Training Cruisers (CT).

Ships Guns   Firepower bonus
Default to
every CL(T)/CT
14cm Single 
15.2cm Single Secondary 
+[math]\displaystyle{ 1\sqrt{N} }[/math]
14cm Twin/Kai/2 
 
 
 · 15.2cm/Kai/2 
 
 

Bofors 
 
 
 · 6" Twin MkXXI 

+[math]\displaystyle{ 2\sqrt{N} }[/math]


Sources: [8] [9]

Heavy Cruisers (CA/CAV)


Accuracy   bonuses for Heavy Cruisers (CA), Aviation Cruisers (CAV), as well as some other "Medium Guns capable Auxiliaries".

  • Other ships like Submarine Tenders (AS) are unmapped yet.
Ships IJN 14 cm Twins 
 
 
IJN 15.2 cm Twins 
 
 
C IJN 20.3 cm 
 
 
 
RM 203 mm  G
All N°1  N°2/3/4(?) 
 
 
Day Night
CA(V) ? ? ? 0 +10 +15 ? 0
Mogami-class (CA/V) ? ? +2 ?
Mogami-class Kai Ni (CAV) ? ? +5 ?
Zara-class ? ? ? +1
Nisshin
Commandant Teste
Kamoi
Mikuma Kai Ni Toku(?)[1]
-6N -6N ? -8 -10N ? -8 -10N?
Jingei-class ? ? ? ? ? ?
  • The table shows an estimated accuracy fit bonus based on having one fit gun equipped.
    • The variable N refers to the number of guns of that category equipped,
    • E.g. 2 guns of 2N = 4 Acc.
  • Bonuses from guns of different classes are simply added together.
    • The guns not mentioned in this table are simply unmapped, and may have bonuses or penalties.
  • The IJN 20.3 cm only provide bonus on CA(V) during night battles.
    • If a N°1 is used alongside any N°2 or/and N°3, then the bonus used for all those guns will be +10 per gun only.
    • Such fit mechanics do not apply to abyssals.[2]

Firepower   bonuses for Heavy Cruisers (CA), Aviation Cruisers (CAV), as well as some other "Medium Guns capable ships" like Seaplane Tenders (AV), Kamoi (AO forms).

  • Other ships like Submarine Tenders (AS) are unmapped yet.
Ships RM 203 mm 
Zara-class +[math]\displaystyle{ 1\sqrt{N} }[/math]

Sources: [11] [12] [13]

12.7cm HA Late Models

As of the 2017-06-23 update, Yura Kai Ni, Mutsuki-classes, and Kamikaze-classes gain accuracy   bonuses with some main Late Models High Angle 12.7cm guns  .

Ship 12.7cm Single HA Mount (LM)  12.7cm Twin HA Mount (LM)  12.7cm Single HA 
CL(T)/CT +4N +2 +2N ?
Yura Kai Ni  +4 +10N ?
Mutsuki-class +5 ? ?
Kamikaze-class ? ? ?
Notes
  • Only Yura Kai Ni  and Satsuki Kai Ni  were tested. It is unknown whether the other ships listed also receive those bonuses, or whether it only works for specific remodels.
  • The variable N refers to the number of guns of that category equipped (ex: 2 guns of 2N = 4).

Sources: [14]

Destroyer (DD) Bonuses

Certain destroyers receive some Accuracy   bonuses when equipped with certain guns or sonars. The resulting accuracy bonus is:

Fit Formula
[math]\displaystyle{ \text{ACC}_\text{bonus} = \sum^{\text{All Groups} } C_{Group} \times \sqrt{N_{Group} } }[/math]
With
  • [math]\displaystyle{ \text{All Groups} }[/math] the equipment groups defined in the following table.
  • [math]\displaystyle{ C_{Group} }[/math] the accuracy modifier of the group, given in the following table.
    • When a ship has additional bonuses to a group compared to her type, this bonus is summed as a separate "Group"
  • [math]\displaystyle{ N_{Group} }[/math] the number of guns of a same group.
Known "C" values
Ships Gear C
Tashkent/Verniy 
 
 130mm B-13 Twin Gun Mount  5
Fletcher-class  5" Single Gun Mk.30 variants 
 
 
4[1]
John C. Butler-class 4[2]
J-class  QF 4.7inch Gun Mk.XII Kai  3
 ASDICs 
 
 
3 [3]
Mutsuki-class  12cm Single Gun Mount Kai 2  5
  1. 2x base 5" Gun  on Fletcher-class gives ~10 accuracy. This is potentially a bug.
  2. Samuel B.Roberts does not seem to receive any bonus from base 5" Gun . This is possibly a bug (maybe related to the bug on Fletcher-class).
  3. There are not enough samples on more than one ASDICs 
     
     
    sonar so it is not clear how does the accuracy bonus scales. This bonus can stack with the accuracy bonus from QF 4.7inch Gun Mk.XII Kai .

Sources: [15] [16]

Arctic Map Bonuses

On all "arctic maps", namely all World 3 maps, as well a some Event maps, the   Arctic Camouflage (+ Arctic Equipment)  gives:

  • 3 Armor   (non-stacking),
  • Some post-cap Evasion  .

Sources: [17] [18]

See Also

Main data sources: