World of Warships: Legends ship guide

Iwami B

Also called: 石见 B Beta
Japan · Tier VIII · Battleship · Premium · Iwami Variant
Torpedo battleshipDeck torpedoes back the main guns; the torps are a brawl-range trap.
Playstyle
  • Anchor a flank at 14-17 km where flanking ships have to cross your torpedo arcs to push
  • The torpedoes are a deterrent that closes off whole lanes (under 15 km threat)
  • Avoid: Drifting broadside to set up a torpedo launch
Key characteristics
Long, heavy torpedoes (15 km)Heavy AP shellsPunchy HE secondariesThick citadel floorVisible torps
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Community Data

Iwami B Community Stats

Across 2,600+ Standard battles from 100+ players, Iwami B averages a 54% win rate, 58,700 damage and 0.7 kills per battle, and survives 34% of them.

Community Data

Iwami B Community Stats

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Playstyle

Overview

Iwami B is a Tier VIII Japanese torpedo-equipped battleship: she carries deck torpedoes reaching 15 km on a hull most BBs lack. The torps are a brawl-range threat that forces approaching ships to peel off or eat a wave; the main battery is the primary damage source, the torps are the trap. Standout traits: heavy AP shells in T8 BBs (13,600, 4th of 33) and best punchy HE secondaries in T8 BBs (2,600, 3rd of 31). The trade is worst torpedo detection in T8 BBs (2.2 km, 7th of 7).

Positioning

Anchor a flank at 14-17 km where flanking ships have to cross your torpedo arcs to push. The torpedoes are a deterrent that closes off whole lanes (under 15 km threat); use that pressure to force enemies into your main battery, then dump torps as a finisher when they commit. Bow on between salvos to keep the citadel angled.

Potato Avoidance

Drifting broadside to set up a torpedo launch

The torpedoes are a trap that closes a lane, not a primary weapon; turn out of a launch if the angle exposes the citadel, and use the threat alone to force lane choices. A dead torpedo BB never drops a torp.

Signature Traits

Heavy AP shells ↗

13600 damage per AP shell, top decile of T8 BBs. A citadel hit lands harder here than anywhere else in the cohort.

ELITE TORPEDOES ↗
  • Long-range torps · 15 km
  • Heavy torpedoes · 19567 damage
Punchy HE secondaries ↗

2600 max HE alpha per secondary shell, best of T8 BBs. Bigger per-shell damage than peers.

Thick citadel floor ↗

50 mm citadel bottom, best of T8 BBs. Deep-water torps and underwater pen do less.

TORPEDO DOWNSIDES ↗
  • Visible torps · 2.2 km
  • Slow torp reload · 150 s
Acquisition

How to get Iwami B

Iwami B is a Premium ship and not available to unlock in the Tech Tree. Acquisition path: Containers. Container chances are shown as the listed odds of receiving this exact ship, dividing grouped ship-pool odds across the resolved ships and including nested container paths when a crate can drop another crate.

While you save up, check active promo codes for free doubloons, camouflages, and other rewards.

Best listed chance for this ship

Show all 4 containers (1 more)
  • Explorer's Chest 0.090909% One of these ships Event · Explorer's Chest · 1 of 11 ships
Official WG availability sources
Show direct source rows

Want the full picture? Each container page charts the odds as you open more crates - including pity guaranteed-reward timers and, for GD Supporters, pack math personalized to your port.

Builds

Pair with a commander whose unique skill complements her main armament; check the build tool for current recommendations.

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Cohort position

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Where Iwami B sits among Tier VIII BBs (33 ships). Notable standouts are shown first; the rest of the cohort-ranked stats are in the expand below. Acquisition variants (Black Friday, Founders Edition) are counted once with their base ship, not as separate peers.

BestSecondary HE alpha2,600 (1 of 6 tied) BestTorpedo range15 km (1/7) Top 10%AP shell damage13,600 (4/33) Top 25%Hit points80,700 HP (8/33) Top 25%Main battery reload25 s (5/33) Top 25%HE shell damage6,500 (7/31) Top 25%Main dispersion207.7 m (7/33) Top 25%Secondary DPM (per side)330,500 (5/33) Top 25%Secondary fire chance10% (8/31) Bottom 25%Fires per minute5.76 (25/31) Bottom 25%Power-to-weight2.46 hp/t (27/33) WorstTorpedo reaction time11.7 s (7/7) WorstTorpedo reload150 s (1 of 2 tied)
See 40 mid-pack stats

Not standouts for Iwami B -- here's where she sits on every other ranked stat in the cohort. Stats tagged NORM are tied across more than half the cohort, so the value is the cohort default rather than a standout.

Max speed28.2 kt(23/33) Concealment15.84 km(21/33) Smoke fire bloom15.4 km(25/33) Air detection12.67 km(19/33) Rudder shift17.2 s(23/33) Turning circle880 m(13/33) Main battery caliber410 mm(10/33) Main battery range17.18 km(17/33) Sigma1.9(11/33) HE DPM124,800(10/31) AP DPM261,120(11/33) Secondary HE pen26 mm(9/31) AP velocity834 m/s(13/33) HE velocity834 m/s(11/31) Time to 90% speed34.6 s(14/33) Acceleration (0-12 kt)14.3 s(25/33) AP arming threshold68 mm(17/33) Engine power145,000 hp(25/33) Power / turn radius164.8 hp/m(25/33) Displacement58,962 t(21/33) AP pen at 10 km611 mm(19/33) Effective HE DPM (incl. fire)172,016(17/31) Secondary range6 km(12/33) AA DPS531(17/33) AA range5 km(19/33) AA threat1,925(16/33) Flak damage per salvo (expected)1,725(11/33) Torpedo damage≈19,567(3/7) Torpedo speed70 kt(3/7) Repair charges3(14/33) Max armor410 mm(13/33) Citadel belt360 mm(11/31) NormSecondary dispersion bracket57(24 of 33 tied at this value) NormAP fuse timer0.033 s(30 of 33 tied at this value) NormAP ricochet start45°(29 of 33 tied at this value) NormAP auto-bounce angle60°(29 of 33 tied at this value) NormTurn speed retained81%(32 of 33 tied at this value) NormRepair heal rate0.5 %/s(24 of 33 tied at this value) NormBow armor32 mm(29 of 31 tied at this value) NormStern armor32 mm(29 of 31 tied at this value)
Survivability
Hit Points80,700
Displacement58,962 t
Hull dimensions
ƒLength x beam at the waterline, plus draft. Length matters when dodging torpedoes; beam and draft shape how hard the ship is to hit.
255.2 x 37.4 m
Armor range19–410 mm
Plate armor thicknesses19, 25, 32, 38, 45, 50, 51, 55, 75, 76, 93, 102, 108, 115, 127, 140, 152, 191, 203, 229, 254, 305, 356, 360, 380, 410 mm
Armor material/layer entries81
Fire resistance
ƒtop hull: 1 − 0.6004 fire coefficient = 40%. Lowers how often hits set you on fire. It does not reduce the damage a burning fire does per second; fires burn at the full rate on every ship.
40%
Fire duration60 s
Fire damage
ƒOne unattended fire: 0.003 of max HP per second (0.3%) × 60 s = 0.18 of the pool; 0.18 × 80,700 HP = 14,526 HP on this ship. 4 fire points can burn at once.
0.3% of HP per second
Flood duration40 s
Flood damage
ƒOne unattended flood: 0.005 of max HP per second (0.5%) × 40 s = 0.2 of the pool; 0.2 × 80,700 HP = 16,140 HP on this ship.
0.5% of HP per second
Torp Reduction
ƒ1 − 0.21 hull torpedo-damage coefficient / 0.333 unprotected baseline = 37%. Reduces torpedo hit damage. It does not affect flooding: floods start as often and tick at the full rate.
37%
Magazine HP
ƒPer-turret powder-magazine HP, a separate pool from the ship's. Penetrating hits wear it down and the turret is likelier to be knocked out as it falls, so a larger pool keeps the guns firing through punishment that silences a peer's.
40,400
Steering gear HP
ƒDurability of the steering gears. As this pool drops, hits are likelier to jam the rudder; unlike most modules the steering can be knocked out and repaired but is never permanently destroyed.
24,200
Effective HP
ƒBase 80,700 HP plus everything Repair Party can restore: 0.005 of max HP per second (0.5%) × 28 s × 80,700 HP = 11,298 HP per charge, × 3 charges = 33,894 HP. Ceiling, not a prediction: a charge only restores damage actually taken, and only the regeneratable share of it. In practice ships realize about half of this, mostly because half the charges go unspent; a charge that is used returns about 97% of the per-charge figure above.
89,667–114,594
Repairable: penetration50%
Repairable: citadel10%
Repairable: steering gear50%
Section HP
Bow section HP
ƒDamage saturation pool for the bow: penetrations here deal their normal share until twice this much penetration damage has landed on the section (2 × 3,800 = 7,600), then further hits on it deal half damage. A penetration deals 0.33 × the shell's max damage; once the section is saturated it deals exactly half of that (0.5 × 0.33 = 0.165 × max damage), so a 3,000-damage shell's pen goes from 990 to 495. Overpens (0.1 × max damage) and citadels (1.0 ×) ignore saturation. Pens on the ship's other, unsaturated sections still deal the normal 0.33 ×. A larger pool keeps that part of the ship taking full damage for longer; a small one saturates fast and protects the ship's HP.
3,800
Casemate section HP
ƒDamage saturation pool for the casemate: penetrations here deal their normal share until twice this much penetration damage has landed on the section (2 × 9,200 = 18,400), then further hits on it deal half damage. A penetration deals 0.33 × the shell's max damage; once the section is saturated it deals exactly half of that (0.5 × 0.33 = 0.165 × max damage), so a 3,000-damage shell's pen goes from 990 to 495. Overpens (0.1 × max damage) and citadels (1.0 ×) ignore saturation. Pens on the ship's other, unsaturated sections still deal the normal 0.33 ×. A larger pool keeps that part of the ship taking full damage for longer; a small one saturates fast and protects the ship's HP.
9,200
Auxiliary section HP
ƒDamage saturation pool for the auxiliary room: penetrations here deal their normal share until twice this much penetration damage has landed on the section (2 × 4,100 = 8,200), then further hits on it deal half damage. A penetration deals 0.33 × the shell's max damage; once the section is saturated it deals exactly half of that (0.5 × 0.33 = 0.165 × max damage), so a 3,000-damage shell's pen goes from 990 to 495. Overpens (0.1 × max damage) and citadels (1.0 ×) ignore saturation. Pens on the ship's other, unsaturated sections still deal the normal 0.33 ×. A larger pool keeps that part of the ship taking full damage for longer; a small one saturates fast and protects the ship's HP.
4,100
Hull section HP
ƒDamage saturation pool for the hull: penetrations here deal their normal share until twice this much penetration damage has landed on the section (2 × 60,500 = 121,000), then further hits on it deal half damage. A penetration deals 0.33 × the shell's max damage; once the section is saturated it deals exactly half of that (0.5 × 0.33 = 0.165 × max damage), so a 3,000-damage shell's pen goes from 990 to 495. Overpens (0.1 × max damage) and citadels (1.0 ×) ignore saturation. Pens on the ship's other, unsaturated sections still deal the normal 0.33 ×. A larger pool keeps that part of the ship taking full damage for longer; a small one saturates fast and protects the ship's HP.
60,500
Superstructure section HP
ƒDamage saturation pool for the superstructure: penetrations here deal their normal share until twice this much penetration damage has landed on the section (2 × 3,500 = 7,000), then further hits on it deal half damage. A penetration deals 0.33 × the shell's max damage; once the section is saturated it deals exactly half of that (0.5 × 0.33 = 0.165 × max damage), so a 3,000-damage shell's pen goes from 990 to 495. Overpens (0.1 × max damage) and citadels (1.0 ×) ignore saturation. Pens on the ship's other, unsaturated sections still deal the normal 0.33 ×. The superstructure is not exempt: it saturates exactly like the bow and stern, so shells aimed at it stop dealing full damage once this pool is used up. A larger pool keeps that part of the ship taking full damage for longer; a small one saturates fast and protects the ship's HP.
3,500
Stern section HP
ƒDamage saturation pool for the stern: penetrations here deal their normal share until twice this much penetration damage has landed on the section (2 × 3,700 = 7,400), then further hits on it deal half damage. A penetration deals 0.33 × the shell's max damage; once the section is saturated it deals exactly half of that (0.5 × 0.33 = 0.165 × max damage), so a 3,000-damage shell's pen goes from 990 to 495. Overpens (0.1 × max damage) and citadels (1.0 ×) ignore saturation. Pens on the ship's other, unsaturated sections still deal the normal 0.33 ×. A larger pool keeps that part of the ship taking full damage for longer; a small one saturates fast and protects the ship's HP.
3,700
Citadel section HP
ƒThis section has no practical saturation cap: every hit here keeps dealing its normal share of damage (on most ships the citadel; on many destroyers the casemate).
No saturation cap
Main Battery
ModuleArtillery: 410 mm/50 10th Year Type mod. A
Mounts / barrels4 mounts / 8 barrels
Reload time25 s
Firing range17.2 km
Turret traverse5.14 °/s
Turret armor508 mm
Turret traverse arcs
ƒHow far each mount can train, in degrees to either side of the mount's own facing. A rear turret with ±150° leaves a 60° blind wedge over the bow; one-sided arcs are wing mounts that cover a single side. The data does not say which way each mount faces, so the arcs are listed per mount without bow/stern angles.
2x ±153°, 2x ±155°
Guns to bear
ƒ180° − 155° (the most restricted aft-facing mount's arc) = 25° off bow; 180° − 153° (the most restricted forward-facing mount's arc) = 27° off stern. How far off the bow (or stern) the ship must angle before every main turret can fire: the widest blind wedge among the rear-facing (or forward-facing) mounts, from each mount's trainable arc.
25° off bow / 27° off stern
Shell Grouping (σ)1.9
Dispersion type
ƒIn practice: 10% tighter (better) horizontal dispersion and 19% more vertical spread at max range (17.2 km) than a standard battleship: about 208 m wide × 166 m tall, against 232 m × 139 m. Also on this curve (19): ARP Haruna, ARP Kirishima, ARP Musashi, Ashitaka, Daisen, Hizen, Hyūga, Hyūga W, Inamura, Ise, Ishizuchi, Iwami and 7 more.
Japanese battleship
Max Horiz Disp
ƒHorizontal dispersion ellipse width at max range, from the dispersion model: σH=(R30·idealRadius−minRadiusidealDistance+minRadius)·30 =(1717730·10−2.81000+2.8)·30=207.7m
207.7 m at 17.2 km
Max Vert Disp
ƒVertical dispersion ellipse height at max range: σV=σH·radiusOnMax =207.7·0.8=166.1m
166.1 m at 17.2 km
Med Horiz Disp
ƒ50%-hit horizontal radius: σH,50=σH·0.6σ =207.7·0.61.9=65.6m
65.6 m at 17.2 km
Med Vert Disp
ƒ50%-hit vertical radius: σV,50=σV·0.6σ =166.1·0.61.9=52.5m
52.5 m at 17.2 km
Turret turn time
ƒ180 degrees / 5.14 deg/s traverse speed = 35 s.
35 s
Shells/min
ƒZero upgrades: 8 broadside guns x 60 / 25 s base reload = 19.2. All upgrades (Main Battery Mod. 3 = -10% reload): 8 broadside guns x 60 / 22.571 s (22.5 s = 158 ticks) all-upgrades reload (25 s × 0.9 Main Battery Mod. 3 = 22.5 s) = 21.3.
Initial: 19.2 → 21.3
HE shells
HE alpha6,500
HE Velocity834 m/s
Fire Chance30%
HE fire DPM vs T8 BB47216
Effective HE DPM vs T8 BB172016
HE penetration
ƒ68 mm ≈ 410 mm caliber / 6 (standard HE penetration ratio).
68 mm
HE full-salvo alpha
ƒ6,500 HE damage x 8 broadside guns = 52,000.
52,000
HE DPM
ƒZero upgrades: 52,000 HE full-salvo alpha x 60 / 25 s base reload = 124,800. All upgrades (Main Battery Mod. 3 = -10% reload): 52,000 HE full-salvo alpha x 60 / 22.571 s (22.5 s = 158 ticks) all-upgrades reload (25 s × 0.9 Main Battery Mod. 3 = 22.5 s) = 138,228.
Initial: 124,800 → 138,228
Fires/min
ƒZero upgrades: 19.2 shells/min × 0.3 (30% fire chance) = 5.76. All upgrades (Main Battery Mod. 3 = -10% reload): 21.3 shells/min × 0.3 (30% fire chance) = 6.38.
Initial: 5.76 → 6.38
AP shells
AP alpha13,600
AP Velocity834 m/s
Min Ricochet45 deg
Guaranteed Ricochet60 deg
Fuse Timer0.033 s
Fuse Threshold68 mm
AP pen max range487 mm
AP overmatch
ƒfloor(410 mm caliber / 14.3) = 28 mm (AP auto-penetrates plating this thick or less).
28 mm
AP Pen Close
ƒAP formula evaluated at muzzle velocity: P=10−7·K·m0.69·d−1.07·v01.38 =10−7·2650·10200.69·0.41−1.07·8341.38=880.5mm.
880.5 mm point-blank
AP Pen Far
ƒSame formula at the ship's max firing range (17.2 km), where the shell has slowed to 542.2 m/s: P=10−7·2650·10200.69·0.41−1.07·542.21.38=486mm.
486 mm at 17.2 km
AP full-salvo alpha
ƒ13,600 AP damage x 8 broadside guns = 108,800.
108,800
AP DPM
ƒZero upgrades: 108,800 AP full-salvo alpha x 60 / 25 s base reload = 261,120. All upgrades (Main Battery Mod. 3 = -10% reload): 108,800 AP full-salvo alpha x 60 / 22.571 s (22.5 s = 158 ticks) all-upgrades reload (25 s × 0.9 Main Battery Mod. 3 = 22.5 s) = 289,215.
Initial: 261,120 → 289,215
AP AOE Radius
ƒAP shell over-penetration splash radius; scales with shell mass. Wickes 102mm = 3, standard 152mm CL ~ 20, Iowa 406mm ~ 270, Yamato 460mm = 400, Incomparable 650mm = 550 (max). Larger value = bigger splash damage area when AP over-pens.
250
Torpedoes
ModuleTorpedoes: 610 mm quadruple
Launchers / tubes2 launchers × 4 tubes = 8 tubes
Reload time150 s
Projectile speed70.0 kt
Range15 km
Maximum simulated damage
ƒMost targets only intersect one hull section, so a hit transfers about 1/3 of the warhead alpha (2/3 when the warhead blast >= 5000 and the burst reaches a second section). For this ship: Dsim=α·c=58,700·0.333=19,567. In battle, a hit on the torpedo belt deals the per-hit figure × (1 − the target's torpedo protection %), a bow or stern hit deals it in full, and a torpedo never counts as a citadel hit.
≈ 19,567
Maximum damage (ammunition)
ƒ58,700 warhead alpha / 3 + 1,400 blast = 20,967. Warhead alpha / 3 plus the blast addend: the per-torpedo damage figure. The 'Maximum simulated damage' row above applies target geometry to the same warhead.
20,967
Torpedo module damage
ƒPer-torpedo module/blast damage parameter. Most torpedoes carry 500 to 2,000; ships announced by WG as dealing increased module damage carry 9,000 to 12,000, so their hits knock out engines, rudders, and turrets far more often. Comparative figure.
1,400
Torpedo detectability2.2 km
Reaction time
ƒHow long a target has to dodge after your torpedo is spotted at its detectability range (lower means less warning): treact=2.2 km70 kt×2.6855=11.7 s. 2.6855 converts knots to m/s on the game clock. Base value; commander torpedo-concealment skills lower it further.
11.7 s
Flooding chance
ƒThis torpedo carries a flooding-chance value of 3.55 per hit, shown as 3.55×100=355%. Values above 100% are normal: in battle the base chance is scaled down by the target's torpedo protection (the Torp Reduction stat on its Survivability card) and any flood-resistance modifiers, so a value above 100% keeps flooding likely even through partial protection.
355%
Torpedo launcher traverse25 °/s
Launch arcswing 134° (one launcher per beam)
Torp Turn
ƒTime to rotate the launchers 180 deg: tturn=180°25°/s=7.2s.
7.2 s
Torp Arming218 m
Per-side salvo damage
ƒOne side firing, all torpedoes hitting: per-side tubes x per-torpedo simulated damage = 4 x 19,567 = 78,268. Each hit on the target's torpedo belt is reduced by its torpedo protection %.
78,268
AA Defense
AA mount points54
Maximum AA range
ƒLongest-reaching family on the in-game AA card. Base AirDefense aura max range is 3.1 km; dual-purpose mount auras extend it.
5 km
25 mm/60 Type96 mod. 118×1 25mm
25 mm Type96 mod. 124×2 25mm
25 mm Type96 mod. 212×3 25mm
100 mm Type98 (DP)
ƒDual-purpose: your secondaries doing double duty against aircraft. The same mounts appear on the Secondary Battery card - shared guns, not extra hardware.
8×2 100mm
Far aura
Guns100 mm Type98 (DP)
Continuous DPS
ƒEffective DPS in in-game units (raw aura damage × 3.5 × hit probability, summed per contributing aura) - matches the Close-range AA DPS headline's currency. Includes 147 from dual-purpose secondaries firing as AA in this range band.
147
Range5 km
Near aura
Guns25 mm Type96 mod. 1 + 25 mm Type96 mod. 2 + 25 mm/60 Type96 mod. 1
Continuous DPS
ƒEffective DPS: 129 raw aura damage × 3.5 × 0.85 hit probability = 384 - the same in-game units as the Close-range AA DPS headline.
384
Range3.1 km
Total DPS in Aura
ƒFar 147 + Near 384 = 531
531
Flak
AA explosions
ƒEach ~2 s salvo fires 2 AA explosions in quick succession, each leaving 4 clouds ahead of the attacking squadron, plus 2 stray clouds farther out that appear off-beat between salvos - up to 10 clouds per salvo × 230 damage each. Planes that fly into a cloud take its damage; clouds dissipate before the next salvo lands. Defensive AA Fire, where fitted, multiplies the AA explosions within each salvo, and commander skills that raise the Number of AA explosions add to it.
2 per salvo, 4 clouds each + 2 outer clouds
Cloud damage
ƒDamage a plane takes for flying into one flak cloud, before any reductions.
230
Cloud spawn chance
ƒEach cloud in the pattern rolls this chance to spawn, so salvos average fewer clouds than the maximum. Often called flak 'hit chance', but spawned clouds always damage planes that fly into them - the roll is on spawning.
75%
Salvo interval
ƒA new flak salvo (the AA explosions above) fires roughly every 2 s.
every ~2 s
Fired by
ƒFlak keeps firing while at least one secondary battery mount is operational - even losing every dedicated AA mount does not stop it.
Secondary battery
Flak zone
ƒThe activation band: flak fires while attacking planes are inside it. Clouds are placed ahead of the planes' path, so clouds can land short of 2.5 km or past 5 km - once planes get inside the band, new salvos stop. AA range bonuses push the outer edge out; the 2.5 km inner edge does not move.
2.5-5 km
S
Secondary Battery
Mounts11
Firing range6.0 km
Shell Grouping (σ)1
Total secondary fires/min (per side)
ƒSum of each gun family's fires/min (per side): 9.6 + 2.2 = 11.8. Per side: the barrels that bear on one broadside target (mounts × barrels / 2). A ceiling: assumes every shell hits and ignores the four-fire cap and Fire Prevention.
11.8
Secondary DPM (per side)
ƒSum across all secondary families of (per-side barrels × 60 / reload_s × alpha), with each reload counted in whole 1/7 s ticks (guns fire on the first tick after the reload), where per-side barrels = mounts × barrels-per-mount / 2 (the guns that bear on one broadside target). Per-family: 8×2 100 mm (8/side) × 60/3 s × 1700 = 272,000 + 3×3 155 mm (4.5/side) × 60/12 s × 2600 = 58,500. Assumes every shell hits (real hit rate is lower; the Brawl matchup tool on the Compare page folds in dispersion + target armor).
330,500
Secondary fire DPM vs T8 BB (per side)
ƒFires/min (per side) 11.8 × (1 − 0.4 fire resistance) × 60 s × 0.003 of max HP per second × 75,900 HP = 97,137. Per side: the barrels that bear on one broadside target (mounts × barrels / 2). A ceiling: assumes every shell hits and ignores the four-fire cap and Fire Prevention.
97,137
Total secondary DPM vs T8 BB (per side)
ƒSecondary DPM (per side) 330,500 + secondary fire DPM 97,137 = 427,637: shell damage plus fire damage against one T8 battleship, every shell hitting.
427,637
Secondary dispersion type
ƒMax dispersion = range (km) × 57 + 30. Each dispersion type sets its own slope; this is not a percentage applied to a standard baseline.
Standard
Max secondary dispersion @ 6 km
ƒ6 km × 57 + 30 = 372 m.
372 m
100 mm Type98 (8×2) (DP)
ƒDual-purpose: the same mounts also fire at aircraft, so they appear on the AA Defense card too - shared guns, not extra hardware.
Caliber100 mm
Reload time3 s
HE alpha1,700
Muzzle Velocity1000 m/s
Fire Chance6%
Secondary fires/min (per side)
ƒ8×2 barrels / 2 sides × 60 / 3 s × 0.06 (6% fire chance) = 9.6. Per side: the barrels that bear on one broadside target (mounts × barrels / 2). A ceiling: assumes every shell hits and ignores the four-fire cap and Fire Prevention.
9.6
HE Pen20 mm
Show 1 more gun family
155 mm 3rd Year Type (3×3)
Caliber155 mm
Reload time12 s
HE alpha2,600
Muzzle Velocity925 m/s
Fire Chance10%
Secondary fires/min (per side)
ƒ3×3 barrels / 2 sides × 60 / 12 s × 0.1 (10% fire chance) = 2.2. Per side: the barrels that bear on one broadside target (mounts × barrels / 2). A ceiling: assumes every shell hits and ignores the four-fire cap and Fire Prevention.
2.2
HE Pen26 mm
Maneuverability
Engine power145,000 hp
Maximum speed28.2 kt
Turning circle radius880 m
Rudder shift time17.2 s
Engine power-boost threshold7.0 kt
Engine spool-up time23 s
Reverse spool-up time11.5 s
Reverse speed
ƒtop speed / 4 + 4.9 = 28.2 / 4 + 4.9 = 12.0 kt. Base value; speed modifiers scale it.
12.0 kt
Crash stop
ƒSeconds from top speed to a dead stop after ordering full reverse: reverse power winds in over the reverse spool-up while water drag does most of the braking, using the ship's own reverse-power ratio. The full curve is on the acceleration chart. Full reverse stops about a quarter faster than a plain Stop order from top speed.
38.5 s
Engine boost threshold (reverse)
ƒSpeed below which the engine's built-in power boost applies in reverse.
9.0 kt
Acceleration 0-90%
ƒTime to reach 90% of top speed (25.4 kt of 28.2 kt).
34.6 s
Acceleration 0-99%
ƒTime to reach 99% of top speed (27.9 kt of 28.2 kt). 99% rather than 100% because true top speed is asymptotic (thrust meets drag), so the last fraction of a knot is never quite gained.
54.8 s
Guns in a full turn
ƒWith the rudder hard over the hull turns 3.6°/s, so a target drifts across the bow at that rate. Turret traverse minus hull turn: 5.14 − 3.6 = +1.5°/s, so the guns hold the target through the turn. Main Battery Mod. 2 (+20% traverse) and Mod. 3 (−15%) move this line.
hold target (+1.5°/s spare)
Concealment
Detectability by sea
ƒBase value, no camouflage. With a Grade IV permanent camo (or any disposable camo): 15.84 km x 0.955 = 15.13 km. Camouflage does not change detectability by air.
15.84 km
With Grade IV camouflage (sea)
ƒDetectability by sea 15.84 km x 0.955 (Grade IV permanent camo or any disposable camo) = 15.13 km.
15.13 km
Detectability by air12.67 km
Smoke firing penalty15.4 km
Detect when firing (sea)
ƒmax(main battery range, sea detectability 15.84 km) = 17.18 km. Equal to the ship's main battery range (never below base detectability): firing makes you visible to everyone you can reach.
17.18 km
Detect when firing (air)
ƒAir detectability 12.67 km + gun-firing bloom 8.2 km = 20.87 km. The bloom tracks main-battery caliber 410 mm × 0.020 = 8.2 km.
20.87 km
Detect when on fire (sea)
ƒSea detectability 15.84 km + 2.0 km while burning = 17.84 km.
17.84 km
Detect when on fire (air)
ƒAir detectability 12.67 km + 3.0 km while burning = 15.67 km.
15.67 km
Guaranteed Detect2 km
✦
Consumables
Damage Control Party∞ charges · 80 s reload · 10 s active
Repair Party3 charges · 80 s reload · 28 s active · 11,298 HP (14% of max HP) total heal (per charge)
ƒ0.005 of max HP per second (0.5%) × 28 s effective active time = 0.14 of max HP × 80,700 HP = 11,298 HP: up to 14% of max HP restored per charge.
· 33,894 HP (42% of max HP) total heal (all charges)
ƒ0.14 of max HP per charge × 3 charges = 0.42 × 80,700 HP = 33,894 HP: up to 42% of max HP if the whole Repair Party loadout is used.
· 404 HP/s (0.5% of max HP) heal per second
ƒ0.005 (0.5% of max HP) × 80,700 HP = 404 HP/s. WoWS heals a flat percent of MAX HP each second, so this rate holds at any health level.
Enhanced Secondary Targeting3 charges · 160 s reload · 30 s active · +100% grouping · -50% dispersion

Under the hood

Show ▾

All values are ship base stats with modifications and upgrade changes denoted inline.

The constants behind the formulas and the long tail: shell and dispersion inputs, fixed-range anchors, salvo math, layered AA. Click the formula chip on any row to see how it is calculated.

Main battery formulas

vs standard BB10% tighter H · 19% taller V
H = horizontal, V = vertical spread. This ship's curve against the standard battleship curve, both evaluated at this ship's max range (17.2 km) with the same model as Max Horiz/Vert Disp: horizontal 208 / 232 m − 1 = -10%, vertical 166 / 139 m − 1 = +19%. Shell grouping (σ) is separate: it sets how shells bunch toward the centre of this ellipse.
Shell scatter width @ 5 km120 m
(166.7 × (10 − 2.8) / 1000 + 2.8) × 30 = 120 m. Horizontal scatter at a fixed 5 km, from the same dispersion model as the rows below - a knife-fight-range anchor comparable across ships.
Shell scatter width @ 10 km156 m
(333.3 × (10 − 2.8) / 1000 + 2.8) × 30 = 156 m. How wide your shells scatter at 10 km, from the same dispersion model as the max-range figure above. Picking a fixed range makes this number directly comparable from ship to ship: max-range dispersion makes a longer-range gun look worse even when it's tighter at any common range. The interactive Dispersion tab on the Charts card plots the full curve from 0 to max range.
Shell scatter width @ 15 km192 m
(500 × (10 − 2.8) / 1000 + 2.8) × 30 = 192 m. Horizontal scatter at a fixed 15 km, from the same dispersion model - the long-range anchor. Only shown when the ship's guns reach 15 km.
Shell scatter height @ 5 km51.9 m
How tall the scatter ellipse is at a fixed 5 km, from the same model, comparable from ship to ship. The height/width ratio is a piecewise-linear curve through three points from the ship's own dispersion data: radiusOnZero=0.2 at 0 m, radiusOnDelim=0.6 at delim·Rmax=0.5·17177=8588 m, and radiusOnMax=0.8 at 17177 m. Below the kink: k=0.2+(0.6−0.2)·50008588=0.4329, so σV=σH·k=120·0.4329=51.9m.
Shell scatter height @ 10 km98.7 m
How tall the same scatter ellipse is at 10 km. Comparable from ship to ship for the same reason as the width value above. The height/width ratio is a piecewise-linear curve through three points from the ship's own dispersion data: radiusOnZero=0.2 at 0 m, radiusOnDelim=0.6 at delim·Rmax=0.5·17177=8588 m, and radiusOnMax=0.8 at 17177 m. Above the kink: k=0.6+(0.8−0.6)·10000−858817177−8588=0.6329, so σV=σH·k=156·0.6329=98.7m.
Shell scatter height @ 15 km143.9 m
How tall the scatter ellipse is at a fixed 15 km, from the same model. Only shown when the ship's guns reach 15 km. The height/width ratio is a piecewise-linear curve through three points from the ship's own dispersion data: radiusOnZero=0.2 at 0 m, radiusOnDelim=0.6 at delim·Rmax=0.5·17177=8588 m, and radiusOnMax=0.8 at 17177 m. Above the kink: k=0.6+(0.8−0.6)·15000−858817177−8588=0.7493, so σV=σH·k=192·0.7493=143.9m.
AP pen 5 km731 mm
AP penetration at a fixed 5 km, from the same ballistic curve as AP Pen Close/Far: the shell's impact velocity at that range fed through the AP formula P=10−7·K·m0.69·d−1.07·v1.38 =10−7·2650·10200.69·0.41−1.07·729.11.38=731mm, where 729.1 m/s is the shell's speed when it arrives at 5 km (from 834 m/s at the muzzle). Fixed anchors make ships directly comparable at the same fighting distance; the Charts card plots the full curve.
AP pen 10 km611 mm
AP penetration at a fixed 10 km, from the same ballistic curve as AP Pen Close/Far: the shell's impact velocity at that range fed through the AP formula P=10−7·K·m0.69·d−1.07·v1.38 =10−7·2650·10200.69·0.41−1.07·6401.38=611mm, where 640 m/s is the shell's speed when it arrives at 10 km (from 834 m/s at the muzzle). Fixed anchors make ships directly comparable at the same fighting distance; the Charts card plots the full curve.
AP pen 15 km519 mm
AP penetration at a fixed 15 km, from the same ballistic curve as AP Pen Close/Far: the shell's impact velocity at that range fed through the AP formula P=10−7·K·m0.69·d−1.07·v1.38 =10−7·2650·10200.69·0.41−1.07·568.31.38=519mm, where 568.3 m/s is the shell's speed when it arrives at 15 km (from 834 m/s at the muzzle). Fixed anchors make ships directly comparable at the same fighting distance; the Charts card plots the full curve.
HE flight time @ 10 km4.98 s
How long an HE shell takes to reach a target at a fixed 10 km, from the same numerically integrated trajectory the Charts card plots. The shell slows under quadratic air drag, adrag=kρv2, where ρ is air density from a standard-atmosphere profile and k bundles the shell's drag coefficient, caliber and mass: k=πCdd28m=π·0.34·0.4128·1016=2.21×10−5. That runs from a 834 m/s muzzle velocity in 0.02 s steps under gravity 9.8 m/s² until the shell lands, then divides by 2.77 because the game clock runs faster than real time. Lower is better, since a faster shell is harder to dodge and needs less lead.
AP flight time @ 10 km4.98 s
How long an AP shell takes to reach a target at a fixed 10 km, from the same numerically integrated trajectory the Charts card plots. The shell slows under quadratic air drag, adrag=kρv2, where ρ is air density from a standard-atmosphere profile and k bundles the shell's drag coefficient, caliber and mass: k=πCdd28m=π·0.34·0.4128·1020=2.2×10−5. That runs from a 834 m/s muzzle velocity in 0.02 s steps under gravity 9.8 m/s² until the shell lands, then divides by 2.77 because the game clock runs faster than real time. Lower is better, since a faster shell is harder to dodge and needs less lead.
Guns per full salvo (alpha, DPM)8
4 mounts × 2 barrels = 8; all 8 bear on the broadside.

Model inputs

Krupp (AP)2,650
Armor-penetration constant of the AP shell; penetration scales straight with it, so a 10% higher Krupp is 10% more penetration at every range.
AP shell mass1,020 kg
Enters penetration as mass^0.69 and slows the shell's drag deceleration, so a heavier shell keeps more velocity at range.
AP drag coefficient0.34
Air drag on the AP shell in flight; lower keeps velocity, and with it penetration, at long range.
AP muzzle velocity834 m/s
Starting speed of the AP shell; penetration scales with velocity^1.38.
HE muzzle velocity834 m/s
Starting speed of the HE shell; sets its flight time and lead.
idealRadius10
Horizontal dispersion growth per idealDistance of range, in 30 m units; the slope of the scatter-width line.
minRadius2.8
Horizontal dispersion at zero range, in 30 m units; the intercept of the scatter-width line.
idealDistance1,000 m
Range step over which horizontal dispersion grows by idealRadius.
taperDist4,000 m
Inside this range the scatter width tapers toward minRadius instead of following the line.
radiusOnZero0.2
Vertical scatter as a share of horizontal at zero range.
radiusOnDelim0.6
Vertical scatter as a share of horizontal at the delim point.
radiusOnMax0.8
Vertical scatter as a share of horizontal at maximum range.
delim0.5
Where the vertical-scatter curve bends, as a share of maximum range.

Torpedoes

Estimated torpedo reaction time11.7 s
2200 m / (70.0 kt × 2.6855) = 11.7 s. detectability / (speed kt x 2.6855 m/s per knot on the game clock).
Torpedo speed70.0 kt
Travel time to max range79.8 s
15000 m / (70.0 kt × 2.6855) = 79.8 s. range / (speed kt x 2.6855 m/s per knot on the game clock).
Tube count8
2 launchers × 4 tubes.
Per-side salvo4 torpedoes
8 wing tubes / 2 = 4: the launchers sit one per beam, so only half of them reach any one side. Each launcher reloads on its own, so she can fire one beam, turn, and fire the other without waiting.
Full-salvo damage156,536
All tubes hitting one target: tubes x per-torpedo simulated damage = 8 x 19,567 = 156,536. Each hit on the target's torpedo belt is reduced by its torpedo protection %.

AA defense

AA DPS at max range147
Only families that reach 5 km contribute at the outer edge of the AA bubble. In-game families: 25mm Type96 single 18x1 -> 128 DPS @ 3.1 km; 25mm Type96 double 24x2 -> 171 DPS @ 3.1 km; 25mm Type96 Triple closed 12x3 -> 85 DPS @ 3.1 km; 100mm65 Type98 8x2 -> 147 DPS @ 5 km.
AA DPS layered by range147 DPS @ 5 km, 531 DPS @ 3.1 km
@ 5 km: 147 from one family; @ 3.1 km: 128 + 171 + 85 + 147 = 531. Cumulative AA DPS at each family range threshold. Inner ranges stack the outer families, so a target closing the distance hits stronger AA bubbles as it crosses each band.
AA DPS at point-blank531
128 + 171 + 85 + 147 = 531 DPS: the sum of every family's average DPS, achievable only inside the closest-range family (3.1 km).
AA threat index1925
128 × 3.1 + 171 × 3.1 + 85 × 3.1 + 147 × 5 = 1925. SUM over AA auras of (aura DPS x aura range km). A plane crossing the AA bubble is exposed to each aura for a time proportional to that aura's range, so long-reach DPS is worth more than the same DPS in a short bubble. Units: DPS*km; used to rank overall AA threat across the cohort.
Near aura range3.1 km

Secondary battery dispersion

Secondary dispersion @ 5 km315 m
Same per-type line evaluated at a fixed 5 km: 5 km × 57 + 30 = 315 m.

Secondary battery firepower

Max HE alpha2600
max(1700 (100 mm), 2600 (155 mm)) = 2600. Maximum HE damage per shell across secondary HE families. Best on this ship: 2600 from the 155 mm family.
Max HE fire chance10%
max(6% (100 mm), 10% (155 mm)) = 10%. Maximum per-shell fire chance across secondary HE families (before target fire resistance is applied). Best on this ship: 10% from the 155 mm family.
Max HE pen26 mm
max(20 mm (100 mm), 26 mm (155 mm)) = 26 mm. Maximum HE armor penetration across secondary HE families (caliber × 1/6 for most nations; 1/4 for German/UK BBs). Shells whose pen falls under a plate's armor thickness shatter for 0 hull damage though fire chance still applies. Best on this ship: 26 mm from the 155 mm family.
Open in Charting Tool

Ship Charts

Background

A version of the A-140-J3 "super battleship" project that had a smaller number of main battery guns as well as more effective dual-purpose artillery and torpedo armament.

Armor Beta

Hull HP 80,700, distributed across 5 hull zones, each with its own plate thicknesses, saturation cap, and pen thresholds. HP caps are estimates.

Bow & stern32 mm

Overmatched by 7 AP guns here: Incomparable SE 25IncomparableYamato and 4 more. Angling still helps against the rest.

Belt / citadel356 mm

Citadels come from a flat broadside at close range; held past ~30° of angle, AP shatters or bounces.

Farming19 mm

Superstructure and extremities take HE pens and AP overpens from nearly any gun: steady chip damage. Fire resistance 40%, fires burn 60s. Range-by-range in the Compare tool →

Section Plates HP cap Threats Tactic
Bow32 mm primary (range 32–360 mm)≈ 4,035 (~5% of HP)
Overmatched by 460mm+ AP (Aki, Musashi)Angle bounces 410mm32 mm: HE pens from 203mm+
Bow-tank fits behind this exterior plate. Saturation is FAST here; the cap is often only a few thousand HP.
Hull (midship)360 mm primary (range 45–380 mm)≈ 60,525 (~75% of HP)
No common AP caliber overmatches360 mm: no common HE pens
Largest HP pool. Citadel sits behind these plates; thinner deck and side plating absorb the rest.
Stern32 mm primary (range 32–356 mm)≈ 4,035 (~5% of HP)
Overmatched by 460mm+ AP (Aki, Musashi)Angle bounces 410mm32 mm: HE pens from 203mm+
Mirror of bow. Same fast saturation.
Citadel356 mm primary (range 38–360 mm)no cap
Citadel pen: full damageOver-pen: ×0.10 damage
Effectively no cap; citadel pool sits at ~165k HP on every ship. An AP citadel penetration deals the shell's full damage, the biggest single hit available; only over-penetrations are damped, to ×0.10.
Superstructure19 mm primary (range 19–410 mm)no cap
Any HE ≥16 mm pens at full damage
Any HE ≥16 mm pens at full damage. HE-spam target, and the section saturates fast (often only a few thousand HP).

Saturation cap = HP a section can absorb before further damage to it is reduced (the "bow-tank" effect). Citadel pool is ~165k on every ship (effectively no cap); damage is gated by pen/over-pen multipliers instead. Superstructure saturates fast but HE always pens regardless of the plate thickness. Rudder (and other module HPs) are a separate pool from ship HP: damaging a module doesn't drain ship HP. Incapacitated modules like the rudder and engine are restored by DCP, but secondary and AA mounts destroyed at 0 HP stay out for the rest of the battle.

Balance History

Balance updates affecting Iwami B. Cards are condensed; use each source link for full context.

Buff ×4Main Battery ×2Torpedo ×1
2026-09-03

September Update: Full Progress Ahead

  • Secondary battery 100 mm guns HE shell penetration increased from 17 to 20 mm.
Read the full official post
2026-07-30

Ministry of Balance: Anniversary Tune-Up

  • Iwami and Iwami B: credit earnings increased by 11.11%.
Read the full official post
2024-12-12

Ministry of Balance: Breaking the Ice

  • We're aiming to boost the performance of the Iwami duo with extra damage output and better torpedoes.
  • Main battery AP shell maximum damage increased from 12,750 to 13,600.
  • Torpedo speed increased from 67 to 70 knots.
Read the full official post
Exteriors

Skins & permanent camouflages

Every custom exterior Iwami B can equip.

  • Iwami B default exterior
    DefaultThe ship’s standard exterior

Primary official WG sources

Filtered to official World of Warships: Legends pages where this ship is a focus, reward, line member, or high-context variant mention.