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HOI4 Dev Diary - Naval Production, Repair and Damage

Hi everyone! Sorry about the late diary. We had to hunt down some gremlins in the machinery before stuff could be screenshotted. Today we are going to talk about quite a lot of big changes to naval production and repair as well as the new critical hits system for ships.

Ship Production
The current system of producing ships where you can assign 15 dockyards to the production of an individual vessel leads to results that are both quite ahistorical as well as not feeling like we want the naval play to feel. With big countries able to replace the loss of a big capital ship without much sweat it makes them less precious, and so we are changing this:
  • A Capital Ship can use up to 5 dockyards in its construction
  • Other ships can use 10 dockyards
  • Convoys can use the full 15
This essentially shifts capital ship construction speed to make each ship slower to make, but you can still build several in parallel. Constructing capital ships is complex and not exactly suitable for optimized assembly lines while we felt this still fit convoys very well with other ships in the middle. Speaking of capital ships, the definition is now a bit more flexible and will depend on the inclusion of certain design elements in your ships (such as a carrier flight deck or heavy guns), so if you construct your ships with those be aware that it will impact how streamlined their construction can be made.

It is also possible to add custom names when you set up construction. The perfect time to remember to name your battleships awesome custom names rather than having to remember and do it once they are done. You can queue up several names if you so wish.

Ship Repair
Repair is also changing drastically. Before, repairing a vessel was free and just took time, now it’s using your naval industry to do so. You can decide how many dockyards to assign as a max and the level of the naval base will decide how much can be leveraged in each one. So if you have a level 5 naval base you can leverage 5 dockyards there and repair 5 ships at once.


Bases can be prioritized for receiving dockyards if you have a lot of fleets suffering at once in various places and can even be disabled for repair so you don't accidentally send ships to repair where the enemy will sink them etc. You can even repair in friendly ports if you have docking rights, but are likely to have lower priority than their ships if there is a competition for attention.

If you look closely at the damaged Deutschland heavy cruiser you will see that there is a warning icon on top of it. This signifies that it has taken a critical hit to its propeller and is suffering a big penalty to speed...

Critical Hits
On top of the propeller damage shown off above there are a lot of different critical hits a ship can suffer in combat. The idea behind these is to add some cool storytelling to the fate of ships, and to introduce some lucky random elements. For example imagine there is a lucky hit on a fast and powerful German surface raiding vessel damaging its propeller or engine. Suddenly it is no longer able to escape the royal navy’s wrath as it has planned to do.

Different kind of hits have different effect, and also will cause different amount of direct damage. We are still finalizing the amount of types we have, but here is a non-complete list to wet your appetites:
  • Main Battery Turret Destroyed - reduced attack on main weapons and damage
  • Secondary Batteries Destroyed - reduced attack on secondary weapons
  • Broken Propeller - lower speed
  • Rudder jammed - reduced ability to disengage
  • Magazine hit - massive damage
  • Torpedo Tubes destroyed - reduced torpedo attack and damage
  • Heavy fires - reduced org and damage
  • Ballast tanks inoperable - reduced stealth for subs
  • Radar Inoperable - reduced detection
Suffering a critical hit is a good reason to repair your ships and they need to be fully repaired to remove the effects of the critical hit. There are several admiral traits designed to help you cope as well.


“Safety First” Lowers the chance of the ships under this admirals command suffering critical hits in the first place while “Crisis Magician” unleashes your internal Scotty which will reduce any effects of critical hits through jury rigged repair, fancy maneuvering and probably a fair amount of god old duct tape.

Is this all? No, there will also be a brand new ship designer and the ability to refit. But that ship is not yet watertight, so it will sail in a future diary instead :)

See you all next week again for more Man the Guns updates!

Rejected Titles:
  • Duct tape and you - keeping the Kriegsmarine afloat in a crisis!
  • The rise of Boaty McBoatface
  • This dev diary was taking on water
  • There is nothing a scottish engineer with a degree in technobabble can’t fix
  • What are you sinking about?
Whoa. Dockyards to repair ships? At the very least, damaging enemy ships will at least substantially impact the enemy power instead of it being a minor inconvinience

  • Magazine hit - massive damage

Can we get detonation ribbons for these?
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Whoa. Dockyards to repair ships? At the very least, damaging enemy ships will at least substantially impact the enemy power instead of it being a minor inconvinience
The idea is to shift naval warfare away from everythign dies right away to a place where not everythign is lost but it costs a lot of time and industry to repair it
Now that repair is specific to a naval base well we have the ability of targeting a specific base in an Air Attack?

BTW I am just loving this expansion thus far. I believe that this is showing to be the best one of all. Please continue the great work.
Cool! Am i right in assuming there wil be some form of new fleet interface, considering the symbols traditionally used for armies in the fleet repair screenshot?
yup. the reason they are army symbols is that they havent all been set up yet everywhere. we got different ones for navies
Awesome !!!!

Is the logic of torpedo damage and naval attack damage seperated now in the new naval combat system???
This would be perfect!!!
I take it that dockyards can be assigned in a way that allows them to be occupied in building ships when not used for repairs. Otherwise you would need a lot of naval build capacity to make this all work.

Some day it would be cool to have dedicated forward repair facilities. But this is a good change in the meantime.
Seems nice and all. One question though; it mentions Main batteries and Secondary batteries. Does this mean the damage number is split inbetween them? Can this be changed with refitting?

Or is this a damage to the i.e. AA guns on a capital ship?
Will it be more expensive to build dockyards? They are currently quite cheap while I think in reality dockyards would be more expensive to build than factories. It is also strange that they do not use consumer goods.