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. Values with a question mark are lacking enough data and so may be outdated and/or erroneous. Empty cases are unmapped yet. 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 "post-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.

Ship Class	IJN 35.6cm KMS 38cm Sov 30.5cm RN 38.1cm	Fr 38cm	RM 381mm	IJN 41cm			USN 16inch Twin			USN 16inch Triple			RN 16inch			IJN 46cm			51cm Twin	51cm Triple
				basic	Triple K2	Twin K2	Mk.I	Mk.V	Mk.VIII	Mk.6 mod.2	Mk.7	Mk.7 +GFCS	Mk.I	+AFCT	Kai +FCR	Proto	46cm	Kai
Gangut-class	+7 Sov 30.5cm: +10	0	+1	-7			??	-5	??		-3		-7	??	??	-7	-18	??	N/A
Kongou-class	+7	0	-2	-5	-5?						-5	-6~7?	-5	-6	-3	-7	-10	-10?
Bismarck-class Vittorio Veneto-class	+4	0?	+1	-5							-5	-4?	-5	??	??	-7	-10	??
Iowa-class	+4?	0?	-2?	-5							0	+2				-7	-10	??
Colorado-class	+1			+2							-2					??	??	-6~7
South Dakota-class										-5 M: +4.6						??	??	??
Richelieu-class	+4	+4~5	-2	-5							-5		-7	-14?	-8	-7	-10	??
Queen Elizabeth-class	+6 RN 38.1cm: +8		+1~2	+2								-2?	+5	??	+3~4	-8	-11	??
Nelson-class	0		0	+3?		0						0	0			??	-2~+1	??
Fusou-class Kai/Ni Ise-class Kai	+4	0	+2	+2							0		0?			-3	-7 F+: -11?	-4?
Ise-class Kai Ni	+4?	0	+1?	+4?	+4?	+6					+1~2				+2	??	-7 F+: -11?	??
Fusou-class base Ise-class base	+2	0	+2	+2							+2	+2?	+3		+3	-3	-7	??
Nagato-class base/Kai																			0	??
Nagato-class Kai Ni	+2?	0	+1?	+5	+5	+6	Mutsu: +2~3	??	??		0		+2?	+4		-2?	-4?	-6?	Nagato: -5 Mutsu: -8	??
Yamato-class	0															+3	+3	+7	0	??
Yamato Kai Ni (FBB)	? [1]															??	-7	??	??	-10

• The table shows an estimated accuracy fit bonus based on having one fit gun equipped.
• For married ships, the overweight penalty is generally reduced by 40%:
  • E.g. a married Kongou with a 46cm receives -6 instead of -10,
  • Some exceptions will receive a bonus instead of a penalty on certain guns after marriage.
• If more than one gun of the same class is used, multiply the modifier by the square root of the number of guns:
  • E.g. a Kongou with two IJN 35.6cm equipped receives √2 x 7 = 9.89.
• If guns from different classes are used together, add the modifiers together.
  • E.g. a Kongou with 35.6cm and 41cm mixed receives 7 - 5 = 2.
  • Exceptions arise where different guns of the same class give different bonuses on certain ships, notably Gangut, with what happens when combining 30.5cm and 35.6cm is still under investigation.

More generally, the accuracy offset can be defined with the formula:

[math]\displaystyle{ W = \sum^{\text{All Classes}} \left ( C_{k} M_{k} \sqrt{N_{k}} \right ) \% }[/math]

With:

• [math]\displaystyle{ W }[/math] the resulting fit bonus or overweight penalty
• [math]\displaystyle{ C_{k} }[/math] the main coefficient of the equipped gun class. Refer to the above table for the coefficients applied to each Battleship for their respective guns.
• [math]\displaystyle{ M_{k} }[/math] the marriage coefficient for the particular gun class. Assumes a value of 0.6 if the ship is married, and if the main coefficient is negative.
• [math]\displaystyle{ N_{k} }[/math] the number of equipped guns for that gun class.

Sources: [2] [3]

Native Guns

Since gun overweight penalty and fit bonuses are not yet all measured for some guns and ships, here is a list of the guns natively used/planned to be used in real life by each ship class.

• The "Twin/Triple" mount distinction is made for convenience, triple guns being heavier than their twin counterpart.
• Equipping ships with those guns may not always be optimal, but this should avoid most overweight penalties.

Large Guns
Nation	Class	Caliber	Twin	Triple
Japanese	Kongou-class Fusou-class Ise-class	35.6cm	35.6cm Twin Gun Mount 35.6cm Twin Gun Mount (Dazzle Camouflage) 35.6cm Twin Gun Mount Kai 35.6cm Twin Gun Mount Kai Ni	Prototype 35.6cm Triple Gun Mount 35.6cm Triple Gun Mount Kai (Dazzle Camouflage)
	Fusou-class Kai Ni Ise-class Kai Ni Nagato-class	41cm	41cm Twin Gun Mount 41cm Twin Gun Mount Kai Ni	Prototype 41cm Triple Gun Mount 41cm Triple Gun Mount Kai 41cm Triple Gun Mount Kai Ni
	Yamato-class	46cm	Prototype 46cm Twin Gun Mount	46cm Triple Gun Mount 46cm Triple Gun Mount Kai
	Yamato-class Kai Ni	51cm	Prototype 51cm Twin Gun Mount 51cm Twin Gun Mount	Prototype 51cm Triple Gun Mount
US	Colorado-class	40,64cm	16inch Mk.I Twin Gun Mount 16inch Mk.V Twin Gun Mount 16inch Mk.VIII Twin Gun Mount Kai
	North Carolina-class South Dakota-class			16inch Triple Gun Mount Mk.6 16inch Triple Gun Mount Mk.6 + GFCS 16inch Triple Gun Mount Mk.6 mod.2
	Iowa-class			16inch Triple Gun Mount Mk.7 16inch Triple Gun Mount Mk.7 + GFCS
British	Queen Elizabeth-class	38.1cm	38.1cm Mk.I Twin Gun Mount 38.1cm Mk.I/N Twin Gun Mount Kai
	Nelson-class	40,64cm		16inch Mk.I Triple Gun Mount 16inch Mk.I Triple Gun Mount + AFCT Kai 16inch Mk.I Triple Gun Mount Kai + FCR Type 284
Italian	Conte di Cavour-class	30.5cm	305mm/46 Twin Gun Mount	305mm/46 Triple Gun Mount
		32cm	320mm/44 Twin Gun Mount	320mm/44 Triple Gun Mount
	Vittorio Veneto-class	38.1cm		381mm/50 Triple Gun Mount 381mm/50 Triple Gun Mount Kai
German	Bismarck-class	38cm	38cm Twin Gun Mount 38cm Twin Gun Mount Kai
French	Richelieu-class	38cm	38cm Quadruple Gun Mount 38cm Quadruple Gun Mount Kai 38cm Quadruple Gun Mount Kai Deux '"Double Twin Guns" in a Quadruple Mount.
Russian	Gangut-class	30.5cm		30.5cm Triple Gun Mount 30.5cm Triple Gun Mount Kai

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
	15.2cm 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	-
	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	14cm Single 15.2cm Single Secondary	+1
	14cm Twin /Kai  · 15.2cm /Kai Bofors 15.2cm · 6" Twin MkXXI	+2

Sources: [4] [5]

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 ships" like Seaplane Tenders (AV), Kamoi (AO forms).

• Other ships like Submarine Tenders (AS) are unmapped yet.

Ships	14cm Twin /Kai	15.2cm /Kai	C	IJN 20.3cm		203mm/53	G
				Day	Night
CA(V)				0	+5 +5N?		0
Mogami-class			+2
Mogami-class Kai Ni			+5
Zara-class						+1
AV/Kamoi (AO)	-6N	-6N		-8 -10N			-8 -10N?

• The table shows an estimated accuracy and/or firepower 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 night fit bonus from the IJN 20.3cm series used to be capped at +15%. However, it is unknown whether this cap has been removed or not from the recent updates.
  • It is possible that certain fit categories only work during the day, but there is no concrete data proving it yet.
  • It is alternatively possible that the night bonus from the IJN 20.3cm series overrides any other categories.
  • 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]}.

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	203mm/53
Zara-class	+1

Sources: [6] [7]

12.7cm HA Late Models

As of 2017/06/23, 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: [8]

Destroyer (DD) Bonuses

Certain destroyers receive some Accuracy bonuses when equipped with certain guns or sonars.

• The bonus accuracy likely takes the form: [math]\displaystyle{ \text{ACCURACY}_\text{bonus} = \text{C} \times \sqrt{\text{N}} }[/math]
  • N being the amount of equipment.

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: [9] [10]

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 Evasion .

Sources: [11] [12]

See Also

Main data sources:

• 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