Combat/Overweight Penalty and Fit Gun Bonus

Hidden fit bonus mechanics are still being investigated to this day, hence the values are not final and may be subject to changes. Cases with a question mark (?) are lacking enough data or are unmapped yet, and so may be outdated and/or erroneous. The developers have also adjusted hidden fits multiple times.

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 , and some also affect Firepower (excluding #Arctic Map Bonuses unic case).
  • Accuracy bonuses work like regular visible stat, see here for more information.
  • 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 [4].

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.

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	-5		-5		-7	-10	-10	N/A	0
[FBB Additional Bonuses]
FBB Additional Bonuses	Gangut-class	-	12						-4							N/A
	Conte di Cavour-class Kai/Nuovo	Kai/Nuovo		14
	Kongou-class	-			3
	Bismarck-class	-						3
	Vittorio Veneto-class	-
	Richelieu-class	-					2		-2
	North Carolina-class	-
	South Dakota-class	-
	Iowa-class	-									7	14
BB Base Bonus			?	?	2		0	2	2		0		-3	-7	?	N/A	0
[BB Additional Bonuses]
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
		Nagato Kai Ni							4	3
	Nevada-class	-														N/A
	Colorado-class	-
	Queen Elizabeth-class	-				2?
	Nelson-class	-
		Nelson Kai	0
BBV Base Bonus			?	?	4		0	2	2		0		-3	-7	-7	N/A	0
[BBV Additional Bonuses]
BBV Additional Bonuses	Fusou-class Kai/Ni	Kai/Ni														N/A
	Ise-class Kai/Ni	Kai/Ni
Yamato-class Base Bonus													3	3	7		2
[Yamato-class Additional Bonuses]
BB	Yamato-class	Base/Kai/Ni	0
FBB		Yamato Kai Ni														-10
BBV		Yamato Kai Ni Juu											-5	-8

Sources: [5] [6]

• old: [7] [8]

Cruiser Bonuses

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		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
	15.2 cm 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	-
	Any Medium Gun	-	-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	14 cm Single 15.2 cm Single Secondary	+[math]\displaystyle{ 1\sqrt{N} }[/math]
	13.8 cm Twin/Kai 14 cm Twin/Kai/2  · 15.2 cm/Kai/2 Bofors  · 6" Twin MkXXI	+[math]\displaystyle{ 2\sqrt{N} }[/math]

With

• N the number of guns of that category equipped.

Sources: [9] [10]

Heavy Cruisers (CA/CAV)

CA(V) as well as other "Medium Guns capable ships" are still under investigation, this information is outdated and may be erroneous.

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(?)	-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.

• As of 13th December 2018 the hidden firepower bonus of 14cm Twin Gun Mount Kai does not work/does not exist^{[citation needed]}.
  • This is probably also true for the 14cm Twin Gun Mount Kai 2 [11]

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: [12] [13] [14]

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: [15]

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
John C. Butler-class		4
J-class	QF 4.7inch Gun Mk.XII Kai	3
	ASDICs	3
Mutsuki-class	12cm Single Gun Mount Kai 2	5

Sources: [16] [17]

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: [18] [19]

See Also

Main data sources:

• https://docs.google.com/spreadsheets/d/1d91OJxKWmqF35DDcxlYoJG0Ndrq0gtwALMNxlh4iiUQ/edit#gid=973638944
• https://docs.google.com/spreadsheets/d/11-nekeN0IBLtzdxxIzV0Gm3T7U4BpCrYA1lGsQYAEJo
• https://docs.google.com/spreadsheets/d/1tN3X92q9zaWC0IMHfgw-dSqWnuscgKJT7ZOf9M9_Hjk/edit#gid=0
• https://docs.google.com/spreadsheets/d/1M0YSCVlnul4Usb8MZ8oluCJAUXyvhU-7MJ4Plcuipds/edit#gid=0
• https://docs.google.com/spreadsheets/d/1Xm5VRj1FwgwlRISAyuwJgOJiBgOGOcGQJNcJ-pZHGFo/edit#gid=0
• https://docs.google.com/spreadsheets/d/1e6U4aLsrbdvkFlxdgT6wuJCmACpuOD3yYN0Om1o24fI/edit#gid=239440540