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HoI4 Dev Diary - Subs and Convoy Raiding

Greetings, I am a game designer new to the HoI4 team. This is my first dev diary, so be gentle ;). Also, sorry for the late post today. I am an American and when it comes to WW2, we show up late.

Today’s diary entry covers our improvements to submarine convoy raiding. In past versions of HoI4, submarines have not really pulled their weight. We have sought to change that and make them worthwhile to build. I recently put these changes to the test by playing a Germany campaign.

My naval plan as Germany was to exploit the central Atlantic and Cap Verde Plain with a submarine wall. This would hopefully prevent England from getting necessary resources from the USA and the colonies. The biggest effect of this resource shortage would be the UK running out of fuel, crippling both their navy and air force. This would hopefully open the UK to sea lioning before the USA joins the war or at the very least, make winning the air war very easy and cause permanent damage to the UK’s fleet.

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We have previously mentioned the spotting system, and how naval task forces are revealed over time. This functions a little bit differently for subs. Spotting an enemy sub outside of combat is based upon chance. The chance for this to happen is based on how quickly the spotter will spot their target. However, it is possible for a submarine to have a large enough advantage in spotting that the submarine task force will not be able to be spotted. However, convoy escorts will still be able to fight against submarines once combat is initiated, even if subs are not normally detectable by enemy taskforces on the map.

This system creates a tech race between sub stealth and sub spotting, with subs having a better chance of getting an advantage in the early game. Previously, submarines would eventually be detected and killed no matter how good at hiding they were. This is no longer an inevitability.

Before beginning the war, I made sure to complete the German naval focus line down to “U-boat Effort.” Along with getting a research speed boost and some dockyards, the focus gives Germany access to a “Cruiser Submarine.” This sub is a sort of tech 2.5 Sub with extended range, some unique module options, including catapult planes, and the ability to be upgraded with a snorkel.

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Part of my plan for giving England a hard time included mining up the English Channel. I executed this plan with a cruiser sub equipped with naval mines and plane catapults. These plane catapults boost the sub’s surface detection, giving them an advantage in being detected and helping them remain invisible, at least for the first couple years of the war.

Sub Minelayer.png


I made a tech 3 sub-variant for minelaying the Eastern North Sea and a tech 3 raider-sub for Cap Verde Plain. When I demanded Danzig from Poland in August of ‘39 I had 79 Subs of various roles ready and much of the Trade Interdiction doctrine complete. This focus on raiding will give my subs a further detection advantage over other countries that have yet to complete their convoy escort doctrines.

Speaking of the naval doctrines, we have made some changes all around to account for the new combat system and apply a bit of balance. In particular, we have given some buffs to the Trade Interdiction doctrine to make it more attractive than it was previously. We have added additional survivability for submarines and more of an edge in surface detection values. Capital ships have received some defensive increases as well.

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Torpedo reveal chance is a new thing for subs. When subs are in combat, attacking no longer guarantees that a sub will reveal itself. Baseline, subs have a 50% chance to reveal themselves when launching a torpedo volley. This can further be improved through doctrines and admiral traits. This makes ambushing protected convoys safer and retreating when too many destroyers show up easier.

In my campaign, I capitulated France in early December of ‘39. To help with the Axis’s naval situation I formed Vichy France. Before France fell they had been contesting my raiding of Cap Verde Plain to the best of their ability, but I was still seeing some success. Forming Vichy France put more ships in the hands of the Axis and would further help to stretch the limits of what England could endure at sea.

With Vichy France on my side, early 1940 saw a massive spike in convoys raided as Cap Verde Plain and the Mid-Atlantic were now completely covered. By this point, I had ~20 dockyards producing subs for minelaying and raiding. All of my newest tech 3 Raiders were seeing great success in under the guidance of Karl Dönitz. Even when contested by British convoy escorts, they were able to get a respectable amount of kills and retreat. Naval bombers were also ramping up operations in the English channel.

casualties.png


We have added a new effect to convoy raiding, war support reduction due to raiding. By mid-1940, Canada had been raided to 0 convoys and had their war support reduced to a point where they were no longer able to support War Economy. This helps to promote raiding and discourages blunt forcing convoys through an area where you are being raided.

Canada War Support.png


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. By mid ‘41 I had naval invaded the UK and was Setup for an attack on The USSR.

See you all next week!

Rejected Titles:
-Raiding and Reaving, 1940 edition
-Subs, they're not complete trash now!
-Under the sea, Darling its better
 
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So are we going to get a feature where navies from several countries can band together so the Axis doesn't get wrecked piecemeal in the early war? Just curious, although it is great we'll get other countermeasures like this and I'm super excited for this expansion
 
I hope way in the future when air combat and AI is further polished, we'll have a way to actually capitulate the enemy through resourse starving and bombing. It should be hard to do that to the point of capitulation, but hey!
 
nice Dev Diary :)
can you make for tanks and aircrafts the same like for the Shipbuilder? (with Different Chassis)
For Tanks with resurching: Engines, put on artelleryguns/Pak/AA with or without turret, Armor, MGs, Stabilisator, and different Tank drives (Christie, Schachtellaufwerk,..)
For Aircrafts: Engines/ double Engine/ Tribble..., Bombload, Rockets, MGs, Kannones, Radar, jet engine
I know it dont fit in this Patch but for the next it would be great and not THAT big of a deal.
 
nice Dev Diary :)
can you make for tanks and aircrafts the same like for the Shipbuilder? (with Different Chassis)
For Tanks with resurching: Engines, put on artelleryguns/Pak/AA with or without turret, Armor, MGs, Stabilisator, and different Tank drives (Christie, Schachtellaufwerk,..)
For Aircrafts: Engines/ double Engine/ Tribble..., Bombload, Rockets, MGs, Kannones, Radar, jet engine
I know it dont fit in this Patch but for the next it would be great and not THAT big of a deal.

I was thinking about that, hopefully next expansion focuses on land combat with an overhaul to FR and SU, making historical templates the best you can make and giving the same treatment given to ships but to tanks (and planes in the future too). And improve how supply lines work, add resource stockpiling (and nerfing refineries), improve the AI. Hopefully all of that would actually make barbarossa hard. That'd be an expansion to dwarf even this one :p
 
Will there be options to outfit submarines with nuclear ☢️ powered reactors to allow greater maneuverability and range? would love to see this as an endgame tech. maybe include in the wunderwaffen dlc pack???

concept started in 1939. can tie in nicely and feel more rewarding for researching nuclear tech. thanks

https://en.m.wikipedia.org/wiki/Nuclear_submarine

on the topic of this, maybe missile cruisers and missile subs could be outfitted properly as well!!
 
nice Dev Diary :)
can you make for tanks and aircrafts the same like for the Shipbuilder? (with Different Chassis)
For Tanks with resurching: Engines, put on artelleryguns/Pak/AA with or without turret, Armor, MGs, Stabilisator, and different Tank drives (Christie, Schachtellaufwerk,..)
For Aircrafts: Engines/ double Engine/ Tribble..., Bombload, Rockets, MGs, Kannones, Radar, jet engine
I know it dont fit in this Patch but for the next it would be great and not THAT big of a deal.

Assuming that the Ship designer works out as we hope it does, we might expand the system to cover tanks and airplanes as well. Some of the backend was made with tanks and airplanes in mind, but we are mainly concerned with overloading the player with design choices during potentially hectic situations in the war (you are trying to micro the encirclement of 6th Army but you also need to design a new tank destroyer…). Ships have a long lead time so we expect you to have to design them less often.

from the ship designer dev diary
 
I VERY much like the sound of this, from a German player perspective at least! No longer now do you need massive numbers of bombers or equal ships to contest the Royal Navy. It sounds that if you manage to get it right you can finally starve the UK of fuel and render their fleet useless!! No more can their fleet patrol endlessly without a thought for fuel!

Of course, I trust if you're playing as the UK you can develop sufficient convoy tactics to keep your convoys going and hold those pesky u-boats at bay.......:D
 
He put England instead of the UK aswell... Americans....
You do know that there are plenty more countries that say England and Soviet Union instead of United Kingdom or U.S.S.R. right?
 
Will there be options to outfit submarines with nuclear ☢️ powered reactors to allow greater maneuverability and range? would love to see this as an endgame tech. maybe include in the wunderwaffen dlc pack???

concept started in 1939. can tie in nicely and feel more rewarding for researching nuclear tech. thanks

https://en.m.wikipedia.org/wiki/Nuclear_submarine

on the topic of this, maybe missile cruisers and missile subs could be outfitted properly as well!!
Pretty good idea and it would be something cool for Germany for the scenario where they either were defeated much later or they had won the war and through the Wunderwaffen program had discovered how to properly make and use submarine nuclear reactors.
 
I like the changes so far, but again, I will have to experience it myself. However, I am quite optimistic about this DLC. I was wondering if there were any thoughts on fleet tenders, and submarine tenders to help with the range of fleets.

I'm not sure how it would be implemented within the game if there was such a thing. Just a separate task force with escorts?
 
I like the changes so far, but again, I will have to experience it myself. However, I am quite optimistic about this DLC. I was wondering if there were any thoughts on fleet tenders, and submarine tenders to help with the range of fleets.

I'm not sure how it would be implemented within the game if there was such a thing. Just a separate task force with escorts?
Interesting idea and to implement it you could automatically attach them to fleets but there are both pros and cons gameplay wise if it is implemented at some point.
 
enjoyable reading and interesting mechanics. I almost forgot about the HOI already, but you are gradually regaining my attention.
 
I really hope you aren't neglecting the other naval doctrines as well. Will some doctrine techs be overhauled to provide bonuses for naval aviation in general and not just carriers? That could be a nice thing. LIkewise having some doctrines do stuff for minelaying would help make a difference.
 
My favorite dev diary so far. The sub part is one of the least interesting parts of the game. Developing and using subs is a wast today IMO.
Sad, when you consider Winstons fear of the German subs.
These changes make me rely excited about this DLC for the first time. Can't wait to ditch the Z-plan for an sub game.
 
kinda. you cant get the planes to strike, they are simply scouts improving spotting abilities for the sub
Does that mean they are not affected by air superiority in their area? Seems kinda odd if they can fly and spot in areas under enemy air cover...
 
Mehh,
This has been the worst area for HOI games for about 9 and a half years now, so I was hoping for a bit more info. But hey i'll keep my fingers crossed that someone new doing the programming might be able to get this shit show figured out.