World of Warships: Legends ship guide

Grom

Also called: 雷霆 Beta
Gun-and-torpedo destroyerA true hybrid: trade gunfire on the caps and torpedo the turns it forces.
Playstyle
  • Sit at the edge of a contested cap from concealment and cycle torpedo waves into lanes the enemy has to use - 7.5 km reach at 72 kt closes the gap fast, though at about 8.3 s of warning the wall works by denying lanes rather than by catching anyone unaware
  • Avoid: Holding 7.5-km torpedoes for a perfect shot
Key characteristics
Improved HE penSmokeEngine BoostFast for the classWeak torpedoes
Related variants

Grom variants in WoWs Legends

These ships share a base hull or event lineage with Grom, but GamingDiver keeps their community stats and ship pages separate when the in-game identity, nation, tier, or premium context differs.

On this page
Community Data

Grom Community Stats

Across 4,800+ Standard battles from 230+ players, Grom averages a 61% win rate, 35,900 damage and 1.1 kills per battle, and survives 42% of them.

Community Data

Grom Community Stats

Log in to GamingDiver and upload your data to see Community Data for Grom: community win rate, damage, survival, spotting, and your own comparison.

Log in & upload to see Community Data

Playstyle

Overview

Grom is a Tier VI European torpedo destroyer reaching 7.5 km. The torpedoes travel at 72 kt, so target reaction time is short - but WG builds her as a gun-and-torpedo hybrid: four hard-hitting HE guns provide the steady damage while the quick, short-lane torpedoes punish anyone who closes. Standout traits: top-decile quick acceleration in T6 DDs (8 s).

Positioning

Sit at the edge of a contested cap from concealment and cycle torpedo waves into lanes the enemy has to use - 7.5 km reach at 72 kt closes the gap fast, though at about 8.3 s of warning the wall works by denying lanes rather than by catching anyone unaware. Drop on probable lanes from cover, stay unspotted between waves, and let the wall do the work. With only HE, aim at superstructures and upper-hull sections where it does full damage instead of shattering on heavy belt armor.

Potato Avoidance

Holding 7.5-km torpedoes for a perfect shot

The kit pays out by saturating lanes, not by waiting for guaranteed broadsides; missed waves still force rotations and protect your team's flank. Idle torpedo tubes are the worst output state.

Signature Traits

Improved HE penetration

HE pen at the 1/4 caliber ratio instead of the standard 1/6. HE-spam is a real damage option here, not just a fire-starter, shared by 5/41 T6 DDs.

Engine Boost

+5% speed (about +2 kt), 100 s duration. Engine Boost consumable gives a small speed nudge - useful for closing a gap or steadying a torpedo run, not for running anything down.

ELITE MOBILITY ↗
  • Fast for the class · 41 kt
  • Quick acceleration
WEAK TORPEDOES ↗
  • Weak torpedoes · 6833 damage
  • Visible torps · 1.6 km
No Propulsion Mod. 2

Propulsion Mod. 2 is not in her upgrade slots, though 38 of 40 other T6 DDs can fit it, so she can't buy its faster pickup to full power and into reverse.

Acquisition

How to get Grom

Grom is available in the Contesting Destroyers branch of the Pan-Europe Tech Tree for 9,000,000 credits after researching it in the branch. Known module upgrades cost up to 2,250,000 credits. Official source cards below may also show its temporary Early Access window before it became a normal Tech Tree unlock. 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.

History: Early Access May 2022 – Oct 2024 (temporary crate drops, now ended).

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

Show Pan-Europe tech-tree branch diagram
Pan-Europe Tech Tree

Grom sits in the Contesting Destroyers branch. The highlighted path shows the local branch context inside the full Pan-Europe tree.

Best listed chance for this ship

Official WG availability sources
  • Continental Voyage: Pan-European Destroyers in Early Access, a New Collection, and More Early Access Start: 2024-09-09 · End: 2024-10-09
    • The new line of Pan-European destroyers includes four ships: Tier IV Muavenet, Tier V Stord, Tier VI Grom, and Tier VII Split.
    • During this update, the new ships will be available in Early Access and can be found in Pan-Eu. Destroyer crates and Pan-Eu. Destroyer Big Crates.
  • Halloween Update: Crimson Tale Tech tree line Start: 2024-10-10
    • New Pan-European destroyers that were previously available in Early Access—Tier IV Muavenet, Tier V Stord, Tier VI Grom, and Tier VII Split—are now fully available as a separate Tech Tree line.
  • September Update: Breeze of Inspiration Early Access 2024-09-05
    • Meet the new Tech Tree line of Pan-European destroyers, available in Early Access from September 9 through October 14: Tier IV Muavenet, Tier V Stord, Tier VI Grom, and Tier VII Split.
    • You can obtain the new destroyers from Pan-Eu. Destroyer crates and Pan-Eu. Destroyer Big Crates, which will be available through the Tempest of Renaissance campaign or in the Store during this update.
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.

Open in Build Tool →

Have a build you swear by? Open it in the Build Tool and hit Save build to share it here, or browse the Ship Builds guide for proven loadouts across the fleet.

Cohort position

Hide ▾

Where Grom sits among Tier VI DDs (40 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.

Top 10%Max speed41 kt (5/41) Top 10%Time to 90% speed7.9 s (3/41) Top 10%Acceleration (0-12 kt)2.2 s (3/41) Top 10%Turn speed retained95.1% (2/41) Top 25%Smoke fire bloom2.45 km (9/41) Top 25%Rudder shift3.2 s (11/41) Top 25%HE fire chance9% (9/41) Top 25%HE velocity900 m/s (9/41) Top 25%Torpedo speed72 kt (7/41) Top 25%Torpedo reload75 s (11/41) Bottom 25%Main battery caliber120 mm (33/41) Bottom 25%Main battery reload6.5 s (34/41) Bottom 25%Displacement3,383 t (32/41) Bottom 25%Torpedo range7.5 km (33/41) Bottom 25%Torpedo reaction time8.3 s (32/41) Bottom 10%Power-to-weight15.96 hp/t (39/41) WorstNo secondaries (37 of 41 in cohort) WorstTorpedo damage≈6,833 (1 of 2 tied)
See 19 mid-pack stats

Not standouts for Grom -- 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.

Hit points15,500 HP(21/41) Concealment6.9 km(21/41) Air detection3.45 km(20/41) Turning circle610 m(17/41) Main battery range10.67 km(19/41) HE shell damage1,900(13/41) Fires per minute5.75(12/41) HE DPM121,435(19/41) Main dispersion95 m(23/41) Engine power54,000 hp(17/41) Power / turn radius88.5 hp/m(20/41) Effective HE DPM (incl. fire)164,434(20/41) AA DPS131(28/41) AA range3.5 km(23/41) AA threat360(27/41) NormMax armor16 mm(26 of 41 tied at this value) NormCitadel belt16 mm(30 of 41 tied at this value) NormBow armor16 mm(34 of 41 tied at this value) NormStern armor16 mm(34 of 41 tied at this value)
Survivability
Hit PointsInitial: 12,900 → 15,500
Displacement3,383 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.
114 x 11.01 m
Armor range6–16 mm
Plate armor thicknesses6, 10, 15, 16 mm
Armor material/layer entries21
Fire resistance
ƒstock hull: 1 − 0.7336 fire coefficient = 26.6%; top hull: 1 − 0.7003 fire coefficient = 30%. 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.
Initial: 26.6% → 30%
Fire duration30 s
Fire damage
ƒOne unattended fire: 0.003 of max HP per second (0.3%) × 30 s = 0.09 of the pool; 0.09 × 15,500 HP = 1,395 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: 0.0025 of max HP per second (0.25%) × 40 s = 0.1 of the pool; 0.1 × 15,500 HP = 1,550 HP on this ship.
0.25% of HP per second
Torp Reduction
ƒ1 − 0.333 hull torpedo-damage coefficient / 0.333 unprotected baseline = 0%. Reduces torpedo hit damage. It does not affect flooding: floods start as often and tick at the full rate.
0%
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.
7,800
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.
4,700
Repairable: penetration50%
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 × 2,300 = 4,600), 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.
2,300
Casemate 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
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 × 11,600 = 23,200), 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.
11,600
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 × 1,100 = 2,200), 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 ×. 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.
1,100
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 × 1,200 = 2,400), 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.
1,200
Main Battery
ModuleArtillery: 120 mm wz. 34/36 Bofors double
Mounts / barrels4 mounts / 7 barrels
Reload timeInitial: 7 s → 6.5 s
Firing range (base)9.7 km
Firing range (top fire control)10.7 km
Turret traverseInitial: 10 °/s → 12 °/s
Turret armor7 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.
±150°, ±147°
Guns to bear
ƒ180° − 150° (the most restricted aft-facing mount's arc) = 30° off bow; 180° − 140° (the most restricted forward-facing mount's arc) = 40° 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.
30° off bow / 40° off stern
Shell Grouping (σ)2
Dispersion type
ƒIn practice: the baseline curve for a standard destroyer -- at max range (10.7 km) shells land in an ellipse about 95 m wide and 57 m tall. Also on this curve (225): AL Avrora, AL Yukikaze, AL Z24, Acasta, Achilles, Adriatico, Aigle, Akatsuki, Akizuki, Albany, Allen M. Sumner, Attilio Regolo and 213 more.
Standard destroyer
Max Horiz Disp
ƒHorizontal dispersion ellipse width at max range, from the dispersion model: σH=(R30·idealRadius−minRadiusidealDistance+minRadius)·30 =(1067030·8−0.51000+0.5)·30=95m
95 m at 10.7 km
Max Vert Disp
ƒVertical dispersion ellipse height at max range: σV=σH·radiusOnMax =95·0.6=57m
57 m at 10.7 km
Med Horiz Disp
ƒ50%-hit horizontal radius: σH,50=σH·0.6σ =95·0.62=28.5m
28.5 m at 10.7 km
Med Vert Disp
ƒ50%-hit vertical radius: σV,50=σV·0.6σ =57·0.62=17.1m
17.1 m at 10.7 km
Turret turn time
ƒ180 degrees / 10 deg/s traverse speed = 18 s.
18 s
Shells/min
ƒZero upgrades: 7 broadside guns x 60 / 7 s base reload = 60. All upgrades (top gun): 7 broadside guns x 60 / 6.571 s (6.5 s = 46 ticks) all-upgrades reload = 63.9.
Initial: 60 → 63.9
HE shells
HE alpha1,900
HE Velocity900 m/s
Fire Chance9%
HE fire DPM vs T6 BB43015
Effective HE DPM vs T6 BB164450
HE penetration
ƒ30 mm ≈ 120 mm caliber / 4 (improved HE penetration: German BBs, Yamato-class, and a handful of others).
30 mm
HE full-salvo alpha
ƒ1,900 HE damage x 7 broadside guns = 13,300.
13,300
HE DPM
ƒZero upgrades: 13,300 HE full-salvo alpha x 60 / 7 s base reload = 114,000. All upgrades (top gun): 13,300 HE full-salvo alpha x 60 / 6.571 s (6.5 s = 46 ticks) all-upgrades reload = 121,435.
Initial: 114,000 → 121,435
Fires/min
ƒZero upgrades: 60 shells/min × 0.09 (9% fire chance) = 5.4. All upgrades (top gun): 63.9 shells/min × 0.09 (9% fire chance) = 5.75.
Initial: 5.4 → 5.75
Torpedoes
ModuleTorpedoes: 533 mm triple
Launchers / tubes2 launchers × 3 tubes = 6 tubes
Reload time75 s
Projectile speed72.0 kt
Range7.5 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=20,500·0.333=6,833. 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.
≈ 6,833
Maximum damage (ammunition)
ƒ20,500 warhead alpha / 3 + 700 blast = 7,533. 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.
7,533
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.
700
Torpedo detectability1.6 km
Reaction time
ƒHow long a target has to dodge after your torpedo is spotted at its detectability range (lower means less warning): treact=1.6 km72 kt×2.6855=8.3 s. 2.6855 converts knots to m/s on the game clock. Base value; commander torpedo-concealment skills lower it further.
8.3 s
Flooding chance
ƒThis torpedo carries a flooding-chance value of 1.19 per hit, shown as 1.19×100=119%. 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.
119%
Torpedo launcher traverse25 °/s
Launch arcscentreline 240°
Torp Turn
ƒTime to rotate the launchers 180 deg: tturn=180°25°/s=7.2s.
7.2 s
Torp Arming223 m
Per-side salvo damage
ƒOne side firing, all torpedoes hitting: per-side tubes x per-torpedo simulated damage = 6 x 6,833 = 40,998. Each hit on the target's torpedo belt is reduced by its torpedo protection %.
40,998
AA Defense
AA mount points6
Maximum AA range
ƒLongest-reaching family on the in-game AA card. Base AirDefense aura max range is 3.5 km; dual-purpose mount auras extend it.
3.5 km
40 mm/56 Bofors № 3Initial: 40 mm/60 Bofors M1936 (2×1) → 40 mm/56 Bofors № 3 (2×2)
13.2 mm Hotchkiss wz. 304×2 13mm
Medium aura
Guns40 mm/56 Bofors № 3
Continuous DPS
ƒInitial: 14 × 3.5 × 1 = 49 → 25 × 3.5 × 1 = 88. Raw aura damage × 3.5 × hit probability, the same in-game units as the Close-range AA DPS headline.
Initial: 49 → 88
Range3.5 km
Near aura
Guns13.2 mm Hotchkiss wz. 30
Continuous DPS
ƒInitial: 15 × 3.5 × 0.95 = 50 → 13 × 3.5 × 0.95 = 43. Raw aura damage × 3.5 × hit probability, the same in-game units as the Close-range AA DPS headline.
Initial: 50 → 43
Range1.2 km
Total DPS in Aura
ƒMedium 88 + Near 43 = 131
131
Maneuverability
Engine power54,000 hp
Maximum speed41.0 kt
Turning circle radius610 m
Rudder shift timeInitial: 5 s → 3.2 s
Engine power-boost threshold39.0 kt
Engine spool-up time7.7 s
Reverse spool-up time3.8 s
Reverse speed
ƒtop speed / 4 + 4.9 = 41 / 4 + 4.9 = 15.2 kt. Base value; speed modifiers scale it.
15.2 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.
18.6 s
Engine boost threshold (reverse)
ƒSpeed below which the engine's built-in power boost applies in reverse.
14.4 kt
Acceleration 0-90%
ƒTime to reach 90% of top speed (36.9 kt of 41.0 kt).
7.9 s
Acceleration 0-99%
ƒTime to reach 99% of top speed (40.6 kt of 41.0 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.
17.7 s
Guns in a full turn
ƒWith the rudder hard over the hull turns 8.3°/s, so a target drifts across the bow at that rate. Turret traverse minus hull turn: 10 − 8.3 = +1.7°/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 (+1.7°/s spare)
Concealment
Detectability by sea
ƒBase value, no camouflage. With a Grade IV permanent camo (or any disposable camo): 6.9 km x 0.955 = 6.59 km. Camouflage does not change detectability by air.
6.9 km
With Grade IV camouflage (sea)
ƒDetectability by sea 6.9 km x 0.955 (Grade IV permanent camo or any disposable camo) = 6.59 km.
6.59 km
Detectability by air3.45 km
Smoke firing penalty2.45 km
Detect when firing (sea)
ƒmax(main battery range, sea detectability 6.9 km) = 10.67 km. Equal to the ship's main battery range (never below base detectability): firing makes you visible to everyone you can reach.
10.67 km
Detect when firing (air)
ƒAir detectability 3.45 km + gun-firing bloom 2.4 km = 5.85 km. The bloom tracks main-battery caliber 120 mm × 0.020 = 2.4 km.
5.85 km
Detect when on fire (sea)
ƒSea detectability 6.9 km + 2.0 km while burning = 8.9 km.
8.9 km
Detect when on fire (air)
ƒAir detectability 3.45 km + 3.0 km while burning = 6.45 km.
6.45 km
Guaranteed Detect2 km
✦
Consumables
Damage Control Party∞ charges · 40 s reload · 5 s active
Smoke Generator2 charges · 240 s reload · 20 s emit / 85 s cloud active · 450 m radius
Choose one
Engine Boost2 charges · 160 s reload · 100 s active · +5% speed bonus
Defensive AA Fire3 charges · 140 s reload · 25 s active · ×3 flak burst boost
ƒRepeats the flak burst pattern ×3 within each salvo - more clouds in the air over the salvo, at the same spots.
Module options (3)

Stats above use the fully-upgraded modules. These are the research-tree alternatives; trade-offs are flagged.

HullUpgrade
  • Hit points12,900 → 15,500
  • Rudder shift5 → 3.2 s
  • Close-range AA DPS29 → 38
  • Turret traverse10 → 12 °/s
Fire controlUpgrade
  • Main battery range9,700 → 10,670 m
ArtilleryUpgrade
  • Base reload7 → 6.5 s

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 DDStandard
The standard destroyer dispersion curve.
Shell scatter width @ 5 km52.5 m
(166.7 × (8 − 0.5) / 1000 + 0.5) × 30 = 52.5 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 km90 m
(333.3 × (8 − 0.5) / 1000 + 0.5) × 30 = 90 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 height @ 5 km25.3 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=0.5 at delim·Rmax=0.5·10670=5335 m, and radiusOnMax=0.6 at 10670 m. Below the kink: k=0.2+(0.5−0.2)·50005335=0.4812, so σV=σH·k=52.5·0.4812=25.3m.
Shell scatter height @ 10 km52.9 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=0.5 at delim·Rmax=0.5·10670=5335 m, and radiusOnMax=0.6 at 10670 m. Above the kink: k=0.5+(0.6−0.5)·10000−533510670−5335=0.5874, so σV=σH·k=90·0.5874=52.9m.
HE flight time @ 10 km6.54 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·0.3177·0.1228·24=7.49×10−5. That runs from a 900 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.
Improved HE PenYes
This ship's HE shells use a 1/4 (~0.25) caliber-to-pen ratio instead of the standard 1/6 (~0.167) - 0.25 in this case. Lets HE pen ~30mm armor instead of ~20mm. Hits every German cruiser (150mm CL, 203mm CA) and BB (350mm+), British heavy cruisers / Lion / Nelson, a handful of other premiums.
Guns per full salvo (alpha, DPM)7
4 mounts × 1.75 barrels = 7; all 7 bear on the broadside.

Model inputs

HE muzzle velocity900 m/s
Starting speed of the HE shell; sets its flight time and lead.
idealRadius8
Horizontal dispersion growth per idealDistance of range, in 30 m units; the slope of the scatter-width line.
minRadius0.5
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.
radiusOnDelim0.5
Vertical scatter as a share of horizontal at the delim point.
radiusOnMax0.6
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 time8.3 s
1600 m / (72.0 kt × 2.6855) = 8.3 s. detectability / (speed kt x 2.6855 m/s per knot on the game clock).
Torpedo speed72.0 kt
Travel time to max range38.8 s
7500 m / (72.0 kt × 2.6855) = 38.8 s. range / (speed kt x 2.6855 m/s per knot on the game clock).
Tube count6
2 launchers × 3 tubes.
Per-side salvo6 torpedoes
2 launchers × 3 tubes = 6, all to either side (centreline launchers train across - full salvo to either side).
Full-salvo damage40,998
All tubes hitting one target: tubes x per-torpedo simulated damage = 6 x 6,833 = 40,998. Each hit on the target's torpedo belt is reduced by its torpedo protection %.

AA defense

AA DPS at max range88
Only families that reach 3.5 km contribute at the outer edge of the AA bubble. In-game families: 40mm 56 Bofors N3 2x2 -> 88 DPS @ 3.5 km; 13mm Hotchkiss wz30 4x2 -> 43 DPS @ 1.2 km.
AA DPS layered by range88 DPS @ 3.5 km, 131 DPS @ 1.2 km
@ 3.5 km: 88 from one family; @ 1.2 km: 88 + 43 = 131. 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-blank131
88 + 43 = 131 DPS: the sum of every family's average DPS, achievable only inside the closest-range family (1.2 km).
AA threat index360
88 × 3.5 + 43 × 1.2 = 360. 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 range1.2 km
Open in Charting Tool

Ship Charts

Background

Grom and Błyskawica entered service in 1937, joining the ranks of the strongest European destroyers of the time. With the outbreak of World War II, the destroyers broke through the Baltic to Britain. After the fall of Poland, the ships joined the Royal Navy and aided in the Norwegian campaign. On May 4, 1940, one of Grom's torpedoes was detonated by a bomb, sinking the ship in minutes.

Armor Beta

Hull HP 12,900 → 15,500 with hull upgrade, distributed across 5 hull zones, each with its own plate thicknesses, saturation cap, and pen thresholds.

Bow & stern16 mm

Overmatched by 126+ AP guns across the bracket. Can’t reliably bow-tank; gets bow-citadelled and overpenned.

Farming10 mm

Superstructure and extremities take HE pens and AP overpens from nearly any gun: steady chip damage. Fire resistance 30%, fires burn 30s. Range-by-range in the Compare tool →

Section Plates HP cap Threats Tactic
Bow16 mm primary (range 15–16 mm)2,300 (15% of HP)
Overmatched by 283mm+ AP (Graf Spee, Scharnhorst)Angle bounces 203mm16 mm: HE pens from 127mm+
Bow-tank fits behind this exterior plate. Saturation is FAST here; the cap is often only a few thousand HP.
Hull (midship)16 mm primary (range 15–16 mm)11,600 (75% of HP)
Overmatched by 283mm+ AP (Graf Spee, Scharnhorst)Angle bounces 203mm16 mm: HE pens from 127mm+
Largest HP pool. Citadel sits behind these plates; thinner deck and side plating absorb the rest.
Stern16 mm primary (range 6–16 mm)1,200 (8% of HP)
Overmatched by 283mm+ AP (Graf Spee, Scharnhorst)Angle bounces 203mm16 mm: HE pens from 127mm+
Mirror of bow. Same fast saturation.
Citadel16 mm primary (range 10–16 mm)≈ 165,500 (effectively 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.
Superstructure10 mm primary (range 10–16 mm)1,100 (7% of HP)
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).
Turret (module, per magazine)separate HP pool, does not drain ship HP7,800 magazine HPTurret knocked outPer-turret powder-magazine HP, a separate pool that does not drain ship HP. As it is worn down the turret is likelier to be knocked out, and a smaller pool gets there faster.
AA mount (40 mm mount)separate HP pool, does not drain ship HP200 per-mount HPDestroyed at 0 HPPer-mount HP for the heaviest AA on this ship. An AA mount destroyed at 0 HP stops shooting down planes for the rest of the battle; DCP does not repair destroyed mounts. HE shells specifically target AA mounts since the small-caliber HP pool falls fast.
Rudder (module)separate HP pool, does not drain ship HP4,700 module HPIncapacitated at 0 HPWhen module HP reaches 0 the rudder locks at its current angle until DCP repairs it. Repair via Damage Control Party.

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.

Exteriors

Skins & permanent camouflages

Every custom exterior Grom can equip.

  • Grom 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.