HoI4 Dev Diary - Subs and Convoy Raiding

[Ethereld]

Speaking of War Support reduction by Convoy Raiding, would constant Strategic Bombing also reduce War Support?

It does already reduce your war support I think, while successfully defending your air against bombers increase it.

 

[SRM]

By early ‘41 the UK had been choked out of convoys and fuel and was unable to keep their navy running and were about open to a naval invasion.

Query: could a British player in this instance have been able to avoid this by rebasing the RN to Newfoundland and getting fuel from the US and Canada via land routes? Or would this have not worked because the fuel would've needed to be shipped by convoys back to Britain and then by convoys back across the Atlantic to the overseas bases?

 

[aokiryu]

As long as it doesn't turn up until around mid 1945, it should be tied to the last sub tech, and require significant resources to produce. In reality it turned up too late to make any impact at all, only 3 were made before the end of the war and all 3 were sunk. As the player, if you wanted to rush research on a tech like this and see it operational much before Mid 45, you would have to ignore research in other areas, and even then, it should still take a fair chunk of time.

Thanks for your opinion, but they didn't sink in the war, they were captured. I agree with the rest of your opinion.

About the reality, please watch this documentary for more precise information about those submarines, it will explain everything including why they were almost not used in the war.

 

[Klausewitz]

I think why I would not support 'carrier subs' is that their capabilities are so miniscule.
They carry 3 (!) planes and very limited ammunition (four torpedoes, three 800 kg bombs, 12 250 kg bombs) and fuel.
It is more a 'commando' weapon but in terms of impact on the scale HoI4 simulates it it is rather better fitted by using a decision even rather than the actual boats.

 

[Alex_brunius]

I think why I would not support 'carrier subs' is that their capabilities are so miniscule.
They carry 3 (!) planes and very limited ammunition (four torpedoes, three 800 kg bombs, 12 250 kg bombs) and fuel.
It is more a 'commando' weapon but in terms of impact on the scale HoI4 simulates it it is rather better fitted by using a decision even rather than the actual boats.

Yeah. The I-400 class submarine as a strike platform basically comes down to, would you choose to build something that has around 1 - 2% of the air-striking power of a real Carrier, for 25% of the cost of a real carrier?

If your answer is heck to the no ( and logically why shouldn't it be ), then why have it ingame as a strike platform?

If it's put ingame it should be as an expensive and large submarine with exceptionally long range and good spotting capability ( potentially aiding other subs in spotting targets through floatplanes )

 

[aokiryu]

Yeah. The I-400 class submarine as a strike platform basically comes down to, would you choose to build something that has around 1 - 2% of the air-striking power of a real Carrier, for 25% of the cost of a real carrier?

If your answer is heck to the no ( and logically why shouldn't it be ), then why have it ingame as a strike platform?

If it's put ingame it should be as an expensive and large submarine with exceptionally long range and good spotting capability ( potentially aiding other subs in spotting targets through floatplanes )

Yamamoto's plan was to build 18 of these subs what would allow one strike force of 54 aircraft if used in large groups it would be strong enough to do some damage.

In the next patch, ships will need to stay in a harbor to repair and update, I would use them in large groups to make surprise harbor attacks on the American coast. Another cool thing that could be implemented with this sub would be events like the Panama canal attack, bombing of American forests (the event would affect the stability and war support of USA).

I would like to see in game one sub that you can use in groups as strike platforms that could reach unexpected places or as one long-range convoy raider. I would like to see this kind of flexibility in the game.

About the cost, I think 25% of the cost of a real carrier is too much, we don't know if it were that costly.

Thanks for your opinion.

 

[aokiryu]

 

[SaydaNeen]

Too early to tell yet because we haven't seen the new research. I do hope there are more options, whether it be in ship designer and or research. The ability to have electric submarines would be a cool addition.

 

[Klausewitz]

Yamamoto's plan was to build 18 of these subs what would allow one strike force of 54 aircraft if used in large groups it would be strong enough to do some damage.

Only against an enemy with no interceptors and when achieving tactical surprise (no radar).
The Seiran was not a very good plane. The huge swimmers effected handling and survivability in air combat.
Pearl Harbor or Trieste are not the gold standard for attacks on enemy ports. The British daylight attack on Wilhelmshaven in September 1939 is much more representative (half the planes lost, no significant damage).
In general I would expect those 18 subs to come in at about 4 times the cost of one carrier I.

 

[aokiryu]

Only against an enemy with no interceptors and when achieving tactical surprise (no radar).
The Seiran was not a very good plane. The huge swimmers effected handling and survivability in air combat.
Pearl Harbor or Trieste are not the gold standard for attacks on enemy ports. The British daylight attack on Wilhelmshaven in September 1939 is much more representative (half the planes lost, no significant damage).
In general I would expect those 18 subs to come in at about 4 times the cost of one carrier I.

In real life, one conventional Japanese air attack in 1945 would have 80-90% of its planes would shot down and because of this Kamikaze were implemented, Yamamoto foresaw this (that Japan would not be able to fight toe to toe against the USA) and ordered the building of those subs to do one kind of guerrilla warfare in the sea. At the end of the war, Japanese submarines were the only thing in IJN that could keep doing something. The idea was not using the I400 as one conventional carrier.

But we are discussing the game, aren't we?

 

[Klausewitz]

Yes, and with that we get into whether or not those subs could be adequatly simulated.

 

[Alex_brunius]

About the cost, I think 25% of the cost of a real carrier is too much, we don't know if it were that costly.

We actually do.

https://en.wikipedia.org/wiki/I-400-class_submarine
"Cost: 28,861,000 JPY in 1942"

Cost of Japanese Carriers:
https://web.archive.org/web/2008040.../navydata/cno/n87/history/wwii-campaigns.html
"3895 Yen/ton" so a 26000 ton Shokaku would be estimated at 101,270,000 JPY

28.86 million / 101.27 million = 28.5% the cost of a Japanese fleet Carrier.

 

[Klausewitz]

Development of the Yen between 1937 (building of Shokaku) and 1942 (I-400).

 

[Alex_brunius]

Development of the Yen between 1937 (building of Shokaku) and 1942 (I-400).

In the linked report:

"The costs of all Japanese ships are as listed in U.S. Strategic Bombing Survey."
My assumption is that this can be assumed to represent the value of a typical ship of the class during wartime (1941-45), not any specific one and not it's value when built. The tonnage of the Shokaku was picked because it's tonnage represented an average sized Japanese fleet Carrier ( larger then the Hiryu, smaller then the Taiho ).

 

[aokiryu]

In the linked report:

"The costs of all Japanese ships are as listed in U.S. Strategic Bombing Survey."
My assumption is that this can be assumed to represent the value of a typical ship of the class during wartime (1941-45), not any specific one and not it's value when built. The tonnage of the Shokaku was picked because it's tonnage represented an average sized Japanese fleet Carrier ( larger then the Hiryu, smaller then the Taiho ).

28,861,000 JPY in 1942. This is the cost of I-404 that were not completed and were bombed in the shipyard, it came from the Japanese wiki. And is the cost of Shokaku based in the JPY in 1942?

https://ja.wikipedia.org/wiki/伊号第四百四潜水艦

It is not one good data to use, and I could not track in the Japanese wiki where this number comes from.

And those American data, it never corresponds to Japanese data, it is always exaggerated based on estimations made by Americans during the war and heavily influenced by post-war cold war propaganda. Please, make your research in Japanese for things about Japan. The same rule applies to research about China and the Soviet Union.

But I understood your point, in competitive gameplay it may not worth it. But this doesn't change my will to see this sub in the game and I am not alone about this.
I think we already discussed enough.

 

[safe-keeper]

Yeah. The I-400 class submarine as a strike platform basically comes down to, would you choose to build something that has around 1 - 2% of the air-striking power of a real Carrier, for 25% of the cost of a real carrier?

If your answer is heck to the no ( and logically why shouldn't it be ), then why have it ingame as a strike platform?

If it's put ingame it should be as an expensive and large submarine with exceptionally long range and good spotting capability ( potentially aiding other subs in spotting targets through floatplanes )

Now that we have, if memory serves, critical hits and damage, "Floatplanes lost" should be a critical hit for subs with planes. It would nullify the bonus from having the plane module.

 

[safe-keeper]

dumbed-down

casuals

See my sig.

 

[Alex_brunius]

28,861,000 JPY in 1942. This is the cost of I-404 that were not completed and were bombed in the shipyard, it came from the Japanese wiki. And is the cost of Shokaku based in the JPY in 1942?

https://ja.wikipedia.org/wiki/伊号第四百四潜水艦

It is not one good data to use, and I could not track in the Japanese wiki where this number comes from.

And those American data, it never corresponds to Japanese data, it is always exaggerated based on estimations made by Americans during the war and heavily influenced by post-war cold war propaganda. Please, make your research in Japanese for things about Japan. The same rule applies to research about China and the Soviet Union.

No matter if you compare the cost of Japanese, American or British submarines, across Japanese, American or British literature I am certain you will find that they were generally at least as expensive if not more expensive per ton to build as a Carrier was, due to all the complexity involved.

The I-400 displaced 6560 tons compared to the 26000 tons of the Shokaku, which is 25.2%, So the 25-28% estimate figure seems very reasonable also from this estimation approach.

If you have any numbers that contradict these in your Japanese research I am very interested in hearing about them, because as you might understand my ability to research original Japanese sources is somewhat limited both due to my language ability as well as my geographical location.

But I understood your point, in competitive gameplay it may not worth it. But this doesn't change my will to see this sub in the game and I am not alone about this.
I think we already discussed enough.

I would also love to see the I-400 submarine and it's extreme patrol range ingame, but not in a capacity where it can use the airplanes to strike ( which we concluded would be horribly ineffective ), rather as scouts to aid it's spotting of enemy ships and convoys.

 

[vermicious knid]

Yes, and with that we get into whether or not those subs could be adequatly simulated.

Given that the new combat system puts everything in one of 4 mutually exclusive areas...I think you'd make the I-400 a carrier with a very very low visibility, a tiny deck, and ridiculous range. Maybe overstate the size of the deck so you can account for the I-400's torpedoes with extra nav bombers (since I'm guessing carriers firing torps isn't a thing the engine will be set up for).

 

[aokiryu]

Given that the new combat system puts everything in one of 4 mutually exclusive areas...I think you'd make the I-400 a carrier with a very very low visibility, a tiny deck, and ridiculous range. Maybe overstate the size of the deck so you can account for the I-400's torpedoes with extra nav bombers (since I'm guessing carriers firing torps isn't a thing the engine will be set up for).

Yea, with this system we would have one carrier that launches torpedos at the same time that it launches planes in battle, what is ridiculous, or we would have one normal submarine with very long range (what is acceptable but not enough). It is because of this I am not happy with using mods to put this ship in the game.

No matter if you compare the cost of Japanese, American or British submarines, across Japanese, American or British literature I am certain you will find that they were generally at least as expensive if not more expensive per ton to build as a Carrier was, due to all the complexity involved.

The I-400 displaced 6560 tons compared to the 26000 tons of the Shokaku, which is 25.2%, So the 25-28% estimate figure seems very reasonable also from this estimation approach.

If you have any numbers that contradict these in your Japanese research I am very interested in hearing about them, because as you might understand my ability to research original Japanese sources is somewhat limited both due to my language ability as well as my geographical location.


I would also love to see the I-400 submarine and it's extreme patrol range ingame, but not in a capacity where it can use the airplanes to strike ( which we concluded would be horribly ineffective ), rather as scouts to aid it's spotting of enemy ships and convoys.

My idea was not using them as a carrier in battle, it was to have one sub with a very long range that if you manage to build enough of them you could make one big fleet of them to launch one attack outside of the naval battle as it was one floating airport if needed.
Alone it would behave as one long-range sub.

You used the weight of the sub with its total displacement including with ballast filled with water (underwater). The standard weight is 3,530 ton. 水上 means over the water.

sorce:
https://ja.wikipedia.org/wiki/伊号第四百潜水艦