Partials/Opening ASW

Commonly referred to as OASW (opening ASW). All eligible ships will perform a regular ASW Shelling attack, following range order in the same fashion as the First Shelling Phase. As these opening attacks happen before the Opening Torpedo Salvo, they may disable or even sink enemy submarines before they have a chance to attack.

OASW has the following trigger conditions:

Only ships listed below can trigger an OASW,
- The ship is not required to be able to perform any ASW Shelling.
They must meet their specific ASW stat threshold and requirements, listed below,

OASW Ship	ASW Stat Required^[1]	Equipment Required^[2]^[3]^[4]
Any DD, CL, CLT, CT, AO^[5]	100+ ASW	1 Sonar Equipped
Kai Ni Juu		+ Bomber / / / Sonar + Any Seaplane Bomber, or Rotorcraft, or Liaison Aircraft, or Dive Bomber, with 1+ ASW
		+ Bomber / / Sonar + Seaplane Bomber, or Rotorcraft, or Depth Charge
Any CVL^[6]^[7]		+ / / / Sonar + Any with 1+ ASW
	50+ ASW	+ / / Sonar + Any with 7+ ASW
	65+ ASW	/ / Any with 7+ ASW
Any DE	60+ ASW	1 Sonar Equipped
Any DE	75+ ASW	Total of 4+ ASW from equipment
Kai Ni D Fletcher-class^[8] John C. Butler-class Kai/Mk.II J-class Kai	Can OASW innately
Kai Ni Go	N/A	/ / / Any with 1+ ASW
	N/A	2 Autogyros -or- 1 Helicopter

↑ The Required ASW Stat does include Visible Bonuses, but does not include Improvements.
↑ Visible Bonuses or Improvements do not count as equipment ASW (e.g. a +6 ASW equipment with +1 ASW bonus does not count as a +7 equipment but just as a +6 one).
↑ When applicable, if all relevant ASW aircraft are in zero plane slots, and no bomber / with 1+ are present in non-zero plane slot, the ship cannot OASW.
↑ Regardless of their ASW stat, Fighters or Carrier Recons cannot trigger any OASW.
↑ Other ASW Shelling capable ships may be able to OASW, but cannot reach 100 ASW using currently available equipment.
↑ The Mogami-class Kou Kai Ni cannot perform any OASW [1]
↑ CVE should be used, as they are the only CVL with base ASW stat.
↑ Kai only for Heywood L. Edwards.

See the list of Anti-submarine Weaponry and ASW Aircraft to better see what can help achieve OASW on a given ship.

Abyssals

Abyssal ships do not follow these rules. The following may perform OASW unconditionally:

Destroyer Ha-Class Late Model Elite
Destroyer Ni-Class Late Model Elite
Light Cruiser Tsu-Class Flagship
Light Carrier Nu-Class (Elite III, Elite IV, all Kai Elite, all Kai Flagship)
Ancient Destroyer Princess II
Seaplane Tender Water Princess (all variants)
Abyssal Kuriles Princess (all variants)
Destroyer Forest Princess (Damaged variants unconfirmed)
American Destroyer Princess (most variants)

Other abyssals cannot perform OASW.

OASW Level Table

The following tables show how much base ASW is needed (in form of required ship level) to enable OASW with a given equipment setup (T4: Type 4 Passive Sonar, T3: Type 3 Active Sonar, DC: Type 3 Depth Charge Projector ASWR: Prototype 15cm 9-tube ASW Rocket Launcher).

Note: Some rare high-ASW equipment (such as Lightweight ASW Torpedo (Initial Test Model)) exist which can allow OASW more easily, but are so rare/low in number that they may not be included in these tables.

DD
Ship	3 Slots						2 Slots				1 Slot
Ship	T4/T4/ASWR 39 + 61	T4/T4/T4 36 + 64	T4/T4/T3 34 + 66	T4/T4/DC 32 + 68	T4/T3/DC 30 + 70	T3/T3/DC 28 + 72	T4/T4 24 + 76	T4/T3 22 + 78	T4/DC 20 + 80	T3/DC 18 + 82	T4 12 + 88	T3 10 + 90
Asashio K2D	85										97	102
Umikaze K2	82						88	92	96	99	110	114
Libeccio Kai Maestrale Kai	52	60	65	70	75	80	90	95	99	104	119	124
Satsuki K2	75				78	82	90	94	98	101	113	117
Fumizuki K2	77				78	82	90	94	98	101	113	117
Asashimo Kai	59	66	70	75	79	84	93	97	102	106	120	124
Grecale Kai	56	63	68	73	78	83	92	97	102	107	121	126
Shigure K2	66	74	78	82	87	91	99	104	108	112	125	130
Ushio K2	67	74	79	83	88	93	102	106	111	116	129	134
Verniy	70	77	81	86	90	95	104	108	113	117	131	135
Akizuki Kai Teruzuki Kai Hatsuzuki Kai	74	81	85	90	95	99	109	114	118	123	137	142
Harukaze Kai	78	84	88	92	96	99	107	111	115	119	131	135
Matsukaze Kai	82	88	92	96	99	103	111	115	119	123	135	139
Kamikaze Kai	80	87	91	95	99	104	112	117	121	125	138	143
Yuudachi K2 Murakumo K2 Hatsushimo K2 Mutsuki K2	80	87	92	97	102	107	116	121	126	131	145	150
Hatsuharu K2	79	87	92	97	102	107	117	122	127	132	148	153
Kisaragi K2	81	88	92	97	102	107	116	121	125	130	144	149
Fubuki K2	83	90	95	99	104	109	118	123	128	132	147	151
Kasumi K2/K2B	82	90	95	99	104	109	119	124	129	134	149	154
Asakaze Kai	86	92	96	99	103	107	115	119	123	127	139	143
Akatsuki K2	86	94	99	105	110	115	126	131	136	141	157	162
Ooshio K2	92	99	105	110	115	120	131	136	141	146	162	N/A
Ayanami K2 Kawakaze K2	94	102	107	113	118	123	133	139	144	149	165	N/A
Arashio K2	105	114	120	126	132	138	150	156	162	N/A	N/A	N/A
Shimakaze Kai Yukikaze Kai	106	115	121	127	134	140	152	158	164	N/A	N/A	N/A

CL/CLT
Ship	3 Slots						2 Slots				1 Slot
Ship	T4/T4/ASWR 39 + 61	T4/T4/T4 36 + 64	T4/T4/T3 34 + 66	T4/T4/DC 32 + 68	T4/T3/DC 30 + 70	T3/T3/DC 28 + 72	T4/T4 24 + 76	T4/T3 22 + 78	T4/DC 20 + 80	T3/DC 18 + 82	T4 12 + 88	T3 10 + 90
Naka K2	48		49	54	59	65	75	81	86	91	108	113
Kinu Kai/Kai Ni	42	52	58	64	71	75		80	86	91	108	113
Yura Kai/Kai Ni	42	52	58	64	71	77	79	85	91	97	114	120
Tama Kai Ni	70					72	84	87	92	97	112	118
Abukuma Kai/Kai Ni	42	52	58	64	71	75	82	88	94	99	117	123
Sakawa Kai	57	63	66	70	74	77	85	88	92	96	107	110
Kiso K2	65		68	72	76	80	88	92	96	99	111	115
Agano Kai Noshiro Kai Yahagi Kai	62	68	71	75	78	82	89	92	96	99	110	114
Jintsuu K2	60		65	70	75	80	90	95	99	104	119	124
Kitakami K2 Ooi K2	65	71	75	79	82	86	94	98	101	105	117	120
Kuma Kai Tama Kai Natori Kai	67	72	76	80	83	87	94	98	101	105	116	119
Sendai K2	64	72	77	83	88	94	105	110	116	121	138	143
Tenryuu Kai Ni	84	87	91	95	99	105	113	118	122	126	139	144

4 Slots CL/CT/DD
Ship	4 Slots
Ship	T4/T4/T4/ASWR 51 + 49	T4/T4/T4/T4 48 + 52	T4/T4/T4/T3 46 + 54	T4/T4/T4/DC 44 + 56	T4/T4/T3/DC 42 + 58	T4/T3/T3/DC 40 + 60	T3/T3/T3/DC 38 + 62
Tashkent Kai	50				54	60	66
Yuubari Kai Kashima Kai	55	62	66	71	75	80	84
Katori Kai	67	75	80	85	90	95	99
Giuseppe Garibaldi Kai	68	77	83	88	94	99	105
Duca degli Abruzzi Kai	70	79	85	91	97	102	108
Gotland Kai	55	58	66	75	83	91	99
Ooyodo Kai	125	132	138	143	148	153	158
Ship	3 Slots
Ship	T4/T4/ASWR 39 + 61	T4/T4/T4 36 + 64	T4/T4/T3 34 + 66	T4/T4/DC 32 + 68	T4/T3/DC 30 + 70	T3/T3/DC 28 + 72
Tashkent Kai	63	72	78	84	90	96
Yuubari Kai Kashima Kai	82	88	93	97	102	106
Katori Kai	97	104	109	114	119	124
Giuseppe Garibaldi Kai	102	111	116	122	128	133
Duca degli Abruzzi Kai	105	114	120	126	132	137
Gotland Kai	95	108	116	124	132	141
Ooyodo Kai	155	163	N/A	N/A	N/A	N/A
Ship	2 Slots					1 Slot
Ship	T4/ASWR 27 + 73	T4/T4 24 + 76	T4/T3 22 + 78	T4/DC 20 + 80	T3/DC 18 + 82	T4 12 + 88	T3 10 + 90
Tashkent Kai	99	108	114	120	126	144	150
Yuubari Kai Kashima Kai	108	115	119	124	129	141	146
Katori Kai	127	134	139	144	149	164	N/A
Giuseppe Garibaldi Kai	136	145	150	156	162	N/A	N/A
Duca degli Abruzzi Kai	140	149	155	161	166	N/A	N/A
Gotland Kai	145	157	165	174	N/A	N/A	N/A
Ooyodo Kai	N/A	N/A	N/A	N/A	N/A	N/A	N/A

Enemy Ships with OASW
Destroyer	Destroyer Ha-Class Late Model Elite Destroyer Ni-Class Late Model Elite Ancient Destroyer Princess
Light Cruiser	Light Cruiser Tsu-Class Flagship
Light Carrier	Light Carrier Nu-Class Elite (III, IV), Kai Elite and Kai Flagship
Seaplane Tender	Seaplane Tender Water Princess

[1] The Required ASW Stat does include Visible Bonuses, but does not include Improvements.

[2] Visible Bonuses or Improvements do not count as equipment ASW (e.g. a +6 ASW equipment with +1 ASW bonus does not count as a +7 equipment but just as a +6 one).

[3] When applicable, if all relevant ASW aircraft are in zero plane slots, and no bomber / with 1+ are present in non-zero plane slot, the ship cannot OASW.

[4] Regardless of their ASW stat, Fighters or Carrier Recons cannot trigger any OASW.

[5] Other ASW Shelling capable ships may be able to OASW, but cannot reach 100 ASW using currently available equipment.

[6] The Mogami-class Kou Kai Ni cannot perform any OASW [1]

[7] CVE should be used, as they are the only CVL with base ASW stat.

[8] Kai only for Heywood L. Edwards.

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[8]