gunboat IJA Ha-Go Battle boat mod.1 "Se-Ha", Ha-Go Battle boat mod.2 "Se-Ni", and Small Escort Boat "Se-Ha Kai"

[aizenns 3,591]

Ha-Go Battle Boat mod.1 (Se-Ha) / 波號戦闘艇一型 (せは艇)

Ha-Go Battle Boat mod.2 (Se-Ni) / 波號戦闘艇二型 (せに艇)

Small Escort Boat (Se-Ha Kai) / 小護衛艇(せは艇改)

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Ha-Go Battle Boat mod.1 "Se-Ha"

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Caption says "Small Escort Boat"

Small Escort Boat "Se-Ha Kai"

 

History

In late of pacific war Japanese need small escort vessel to defend boats. In that time they have "Soukou-Tei" (AB), but it have complex structure so it production is not enough. So they plan easy structure boat that able to build small docks.

They plan two: using 2x 150HP engine and 2x 60HP engine. First one is mod.1, and second one is mod.2.

Mod.2 (Se-Ni) launched October 1944, and tested. Army require over 12 knots, but mod.2 have only 9 knots. Because of it they abandon project of mod.2.

 

Mod.1 (Se-Ha) launch December 1944, and tested 21 to 23. This boat have better speed than mod.2, but they think modify hull and it will get more good speed.

Second prototype of Mod.1 (Se-Ha Kai) launch July. Tested August 2-5, and it reach 13 knots. This boat named "小護衛艇 / Small Escort Boat".

 

Ship hull is V-type displacement ship, and using lots of straight line. Outboard is thin steel (all welding), and use large stringer.

Armor is only steering room, and make command place hole top of steering room.

 

Curiously, this boat have cooking equipment using engine engine exhaust. This machine able to cook two rice bowl in 20 minutes by one engine.

 

 

Specification

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Ha-Go Battle Boat mod.1 (Se-Ha)

Length				18.000 m
Width				3.500 m
Depth				1.700 m
Displacement (Full load)				25.170 t
Draft		Bow		0.695 m
		Stern		1.165 m
		Average		0.930 m
Speed (Full load)		Max		12.2 kt
		Standard		11.7 kt
Cruise range				150 hours
Engine		Name		Type 4, 130 HP diesel engine
		Number		2
		Power	Max	150 HP (1500 rpm)
			Standard	130 HP (1430 rpm)
Weapon	5.7cm ship gun				1
	Type 4, tube-based twin 20mm AA machine gun				1
	Depth charge dropper (mount 3)				2
	Ship radio Ko				1
	Vehicle radio Hei				1
	Ra-Go sonar				1

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Ha-Go Battle Boat mod.2 (Se-Ni)

Type	Steel Shallow displacement
Length	16.000 m
Width	3.500 m
Depth	1.700 m
Own Wight	11.25 t
Speed	Max 9.85 kt Standard: 9 kt
Cruise range	100 hours
Engine	60HP Diesel engine	2

 

		Standard load	Full load
Displacement		15.31 t	18.06 t
Draft	Bow	0.59 m	0.68 m
	Stern	0.94 m	0.97 m
	Average	0.77 m	0.83 m

 

Weapon	37mm ship gun	Bow deck	1
	Type 4, 20mm twin AA gun	Rear deck	1
	Depth charge dropper	Stern deck	2
	Ship Radio Ko	Steering room	1
	Vehicle Radio Hei	Steering room	1

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Small Escort Boat (Se-Ha Kai)

Length				23.000 m
Width				3.500 m
Depth				1.800 m
Displacement (Full load)				28.870 t
Draft		Bow		0.661 m
		Stern		1.192 m
		Average		0.927 m
Speed (Full load)		Max		13 kt
		Standard		12 kt
Cruise range				100 hours
Engine		Name		Type 4, 130HP diesel engine
		Number		2
		Power	Max	150 HP (1500 rpm)
			Standard	130 HP (1430 rpm)
Weapon	Type 4, tube-based twin 20mm AA machine gun				3
	Depth charge dropper (mount 3)				2
	Ship radio Ko				1
	Vehicle radio Hei				1
	Ra-Go sonar				1

 

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Floor Plan of Small Escort Boat

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1. Rigging storage
2. Crew chamber
3. Ammunition box storage
4. Steering room
5. Engine room
6. Ammo and depth charge storage
7. Warehouse
8. Fuel tank
9. Fuel tank
10. Main engine
11. Fuel tank
12. 1st stage ammo racks
13. 20 mm twin AA cannons
14. 1st stage ammo racks
15. Command section
16. Handrail
17. Ventilation tube
18. Depth charge lifting device
19. Depth charge dropper
20. Couch
21. Depth charge
22. Ra-Go device (sonar)

 

 

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Blueprint of Ha-Go battle boat mod.2 "Se-Ni"

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Blueprint of Experimental 130HP diesel engine (for Se-Ha and Se-Ha Kai)

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Photo of Experimental 130 HP diesel engine

 

Sources

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Photo

Fujita Masao (2008) "Unknown records of 'Army Shipping Units [2]' " Maru, 61(5): 120

 

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History and floor plans

Okumoto Gou (2016) "Boats and Ships of Japanese Army: For Landing, Transporting, Escort, Attack and special ships", Dai-Nippon Kaiga publishers

ISBN978-4-499-23177-0 C0076

 

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Specification and blueprint of Ha-Go battle boat mod.2 "Se-Ni"

No.10 Army technical research institute (December 15, 1944) "Ha-Go battle boat mod.2 research report)

第十陸軍技術研究所(昭和十九年十二月十五日)「波号戦闘艇二型研究報告」

flame number 119-125

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Blueprint and photo of 130HP diesel engine

No.10 Army technical research institute (November 11, 1944) "Experimental 130HP diesel engine research report)

第十陸軍技術研究所(昭和十九年十一月三日)「試製百三〇馬力「ジーゼル」発動機研究報告」

flame number 104-112

 

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Specification of Ha-Go battle boat mod.1 "Se-Ha" and Small Escort Boat "Se-Ha Kai"

No.10 Army technical research institute (July 25, 1945) "Small Escort Boat Trial Plan"

 

第十陸軍技術研究所(昭和二十年七月二十五日)「小護衛艇試験計画」

 

 

 

 

Edited September 21, 2019 by aizenns

[Princess_Pinch 5,625]

Open for discussion. 

[Milocat 4,857]

+1, these would all be good tier 1 gunboats.  

[BrentD15@psn 1,117]

+1 for the tech tree.

[gennaroita 113]

+1 more japanise boats 

[Tasty95215 2,099]

Just to be clear, the first version of the Se-Ha is already in the game as the Seha-Tei Model 1, right? In that case there's really only the Se-Ni and the Se-Ha Kai to be added here.

 

I'll be honest - the Se-Ni seems way too slow, and the guns aren't enough to make up for its slowness.

 

On the other hand, the Se-Ha Kai seems like it'd be quite decent - the dual 20mm guns are fairly powerful on the in-game Se-Ha, and having three of them in exchange for the (powerful, but slow-reloading and hard to aim) 57mm gun seems like it's worth the trade. It helps that the Se-Ha Kai is just a bit faster than the very slow Se-Ha.

[aizenns 3,591]

1 hour ago, Tasty95215 said:

Just to be clear, the first version of the Se-Ha is already in the game as the Seha-Tei Model 1, right? In that case there's really only the Se-Ni and the Se-Ha Kai to be added here.

 

I'll be honest - the Se-Ni seems way too slow, and the guns aren't enough to make up for its slowness.

 

On the other hand, the Se-Ha Kai seems like it'd be quite decent - the dual 20mm guns are fairly powerful on the in-game Se-Ha, and having three of them in exchange for the (powerful, but slow-reloading and hard to aim) 57mm gun seems like it's worth the trade. It helps that the Se-Ha Kai is just a bit faster than the very slow Se-Ha.

Yes, Se-Ha (Ha-Go mod.1) is already in game.

 

I agree about Se-Ha Kai (small escort boat). It able to aiming 4 barrels of 20 mm on front and side, and maximum 6 barrels so I believe it will be one of the best MGB in rank 1.

[aizenns 3,591]

Spoiler

 

 

I find both clear photo scans of Se-Ha and Se-Ha Kai !!

Photo from 世界の艦船1996年2月号「昭和の日本陸軍船艇」page 34-35

[N-Glycerin@psn 89]

The small escorts boat with the 3 pairs of 20mm guns looks pretty cool. Would be a nice addition to rank I. Japan doesn't have many boats that really stand out in rank I apart from the CH-8 (can't remember the new/proper name). +1

[aizenns 3,591]

35 minutes ago, *N-Glycerin said:

The small escorts boat with the 3 pairs of 20mm guns looks pretty cool. Would be a nice addition to rank I. Japan doesn't have many boats that really stand out in rank I apart from the CH-8 (can't remember the new/proper name). +1

No.4 class Subchaser.

I agree, I think Se-Ha Kai will be very good rank 1 boat, perhaps better than naval Hayabusa-Tei type MGBs (not come game yet)

[N-Glycerin@psn 89]

Well you know what they say; 6 20mm guns are better than 2.

[aizenns 3,591]

I update section of floor plans of Small Escort Boat "Se-Ha Kai" !

Add description of each numbers on the drawings.

 

Spoiler

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Floor Plan of Small Escort Boat

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1. Rigging storage
2. Crew chamber
3. Ammunition box storage
4. Steering room
5. Engine room
6. Ammo and depth charge storage
7. Warehouse
8. Fuel tank
9. Fuel tank
10. Main engine
11. Fuel tank
12. 1st stage ammo racks
13. 20 mm twin AA cannons
14. 1st stage ammo racks
15. Command section
16. Handrail
17. Ventilation tube
18. Depth charge lifting device
19. Depth charge dropper
20. Couch
21. Depth charge
22. Ra-Go device (sonar)

 

Edited September 21, 2019 by aizenns

[Pony51 6,572]

On 09/11/2018 at 14:19, aizenns said:

Curiously, this boat have cooking equipment using engine engine exhaust. This machine able to cook two rice bowl in 20 minutes by one engine.

 

This is Japan, of course!

[OKAZAQI 166]

+1

[leroyonly 4,311]

As the IJA Ha-Go Battle Boat Mod. 1 "Se-Ha" has been implemented previously,

 

Moved to Implemented Suggestions.