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HOI4 Dev Diary - New Naval Combat

Hi everyone! Since forums were all down yesterday the diary is coming today instead :) Today we are going to look at core changes to naval combat coming in 1.6 Ironclad. We have already discussed how missions are changed as well as basics of the new spotting system in a previous diary and a future one will be fully dedicated to submarines so I will only cover them a little for how the interact with regular fleet battles today. So lets charge in!

Its best to start by looking at problems in the old system so you can see how we have tried to solve them and iterate. We identified the following:
  • Battles are extremely decisive so tiny mistakes have bad consequences
  • Combats tend to snowballs as everyone and their mother’s fleet pile in
  • A big fleet was always better, together with the above point promoting doomstacking
  • The interface gets very confusing as ships close with each other. Distance overall is very hard to show and balance.
  • It is easy to miss a combat happening while busy elsewhere.
  • Its “simulation nature” made balancing an incredibly hard problem. Resulting in things like the all-battleship fleets performing well.
“Battle-lines”
battle.jpg


To deal with distance and screening issues we have split up the battle in 4 areas per side to represent position and distances.

Screens - Your screen ships go here. Screens are the closest to the enemy and protect the ships behind them (details below).
Battle line - This is where your big guns sit. Heavy cruisers, Battleships etc. Anything with heavy long range guns. These guys also help to protect carriers and convoys behind them.
Carriers - Furthest back are carriers protected by the other two lines. This is also where convoys will be if part of the combat (say during invasion or a convoy raid battle).
Submarines - Under the sea. This area is actually two as we separate located submarines (which can be engaged with depth charges) from unlocated submarines.

By splitting things up in discrete distances unlike the old system we can more easily capture the impact of distance and positioning, and keep it easier to see what is going on at a glance.

The area they are assigned to depends on the weapons they have, which makes things tie in neatly with the ship designer. Rules for combat are now largely depend on how different weapons interact with the areas, so it is important to go over them before we continue. We also show these summarized at the top of the combat screen for quick information and to help you evaluate the combat situation:
stats.jpg

Light Guns - These are smaller caliber guns. The armament on destroyers/light cruisers and secondary armament on heavier ships. Their job is to hit and kill smaller fast moving ships. They generally do not have the armor piercing to lay down serious hurt on capital ships. Light guns attack ships one line over. So screen ships can shoot other screen ships, and when there are no more shoot the enemies capital ships. Capital ships with secondaries can fire from behind the safety of the screens at the enemy screen.

Heavy Guns - These are hard hitting armor piercing guns designed to take out big ships. They have trouble hitting small fast ships, but when they do it is for significant damage. Heavy guns have the range to fire over one of the enemy lines. So they will be hitting the enemy battle line even if it is screened.

Torpedoes - These are the big capital killers. They ignore armor, and have big damage but are terrible at hitting fast/small ships. Torpedoes can hit any line as long as it is not screened properly. So if your screening is down to 50% then half of the enemy torpedoes can be fired at your battle line, and if the battle line is also weak some torpedoes can slip through and hit carriers or convoys.

Anti-air - AA works a bit different. When firing back at enemy planes a ship will also get a part of the fleet’s AA armament to help it, so it’s quite nice to make sure your support ships (or battleships if you focus on carriers) are stacked with as much AA as possible.

Depth Charges - This is the only weapon that can hurt subs, and it only works versus revealed subs.
Carrier Planes - Carriers can carry different kind of planes. Naval and dive bombers help attack other ships and fighters help protect yourself. The whole air model in naval combats is now more in line with the rest of the game and takes place in the airzone as you would expect. So can now be disrupted etc. This fixed a bunch of issues we had with the interaction between land based air and carriers.

sub.jpg


Next to the weapon summaries we also display the side’s positioning value. This is a value simulating how well positioned your task forces are. A low positioning could for example mean that all your screens are scattered in a storm and your capital ships are wide open to attack. Positioning affects screening directly and a low value will directly hurt the fighting abilities of the ships as they wont be in optimal range, have another ship fouling the range etc. A big effect on positioning is the relative sizes of the fleets. So the bigger fleet will have an inherent penalty to its positioning versus a smaller, more easily controlled force. An admiral’s maneuver skill helps with this though. There are also traits like Lone Wolf and the Capital Ship Raiders tech from the Trade Interdiction doctrines that help increase this penalty for the enemy. The idea is to make smaller capital raiding forces more competitive if you tech right and have a trained Admiral in charge.

screening.jpg


Tooltips for ships now give great breakdown on where the damage is coming from so you can see how well (or not) a particular weapon type is doing, there are also totals summarized in the top of the interface.
dmg.jpg



Entering and exiting combat
After the initial battle starts, further task forces can join. When they do they get put in the “Incoming” box, much like before. The time spent there depends on their org levels. The lower the longer they have to wait to join. Org is affected by moving, but also by giving manual orders to fleets (we want you to plan ahead, not react for max efficiency). Whenever ships are called to a combat, they will take an organization hit, which slows down their joining. Similar delays also apply for missions like convoy raiding or escort at suboptimal efficiency so it’s harder to bring all your power to bear at the same time.

On the flip side, if you take out the enemy side before the incoming ships arrive, the battle ends and you can run away (or the sides have to re-spot each other if they still want to fight), the idea is to help subs and other raiders out by allowing fast hit-and-run battles.

run.jpg


As for exiting combat that is both something you can order directly and something that happens when ships take enough damage (remember, you set up aggression levels to control how risky you want your task forces to be). Retreating is a process that takes some time. It is affected by doctrines, traits, weather, terrain, and the speed of the ship. We show it as a progress bar so you can bite your nails as the enemy pride of the fleet slowly gets away. Note that we also now have critical hits which will slow down ships and making it harder to run - a ship with a jammed rudder has a wooping 90% penalty to escaping. Escaping is an important part in keeping battles from being too decisive.

This is also where submarines come in. They follow normal torpedo rules, but also free to circumvent them when it comes to escaping ships. So if you have subs hiding in your battle they can engage the enemy capitals as they start to run (of course this reveals them, depending on doctrine levels, leaving them open to return fire from anti-sub vessels).

See you next week for a look at submarines :)

image.png


Rejected Titles:
- Sinking inside the box for a change
- Bravely retreating in the face of underwhelming odds
- Man, those guns!
- "Stop writing dumb titles and post already podcat!"
 
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Great job and great dd guys! :) Question: If I have two task forces in a battle with different commanders, will I get the benefit from both of their traits, or just the one in general command? Ie. screen tf with lancer admiral and a carrier tf with carrier operations admiral.
 
Great job and great dd guys! :) Question: If I have two task forces in a battle with different commanders, will I get the benefit from both of their traits, or just the one in general command? Ie. screen tf with lancer admiral and a carrier tf with carrier operations admiral.

A stab in the dark, but I'm fairly certain you wouldn't put your carriers and screens in different task forces... better way to phrase would have been if the patrol and the strike forces were under different admirals.
 
Looking good. I take it hedgehogs for ASW are counted as depth charges and blasting the conning tower off a surfaced sub was to difficult to bring into the game. I'm already saving podcasts to binge on when this is realised.
 
Has there been any comment on what happening with meshing the TFV trees with the UK's alternate history paths? The only comment on it i could remember was in the 1st UK Dev Diary where it was said it would be looked at later in development.
 
And air attacks are completely random or go for capital ships primarily? (already assuming they disregard screening).
they use various priorities, but prefer capital ships very much. they also prefer more wounded ships
Does the "wounded" part count the new critical hit system as well as HP loss? I'm picturing a scenario where the battle ends with one capital at 78% HP and no critical damage and another at 90% HP but a broken propeller (shown as -90% speed in an earlier dev diary), or other such crippling damage.

Specifically the criticals:
  • Main Battery Turret Destroyed - reduced attack on main weapons and damage
  • Broken Propeller - lower speed
  • Rudder jammed - reduced ability to disengage
  • Heavy fires - reduced org and damage
  • Ballast tanks inoperable (if planes can target spotted subs)
Would merit an increased priority for naval bombers. Likewise wouldn't any carrier with less than 25% of it's planes operational be equivalent to a battleship with the main battery turrets knocked out? Again I think a situation where Carrier A has moderate HP damage but most of it's planes flying and Carrier B is almost unblemished but set out of port with barely any planes on deck... B should be what gets priority targeting for air missions.
 
Likewise wouldn't any carrier with less than 25% of it's planes operational be equivalent to a battleship with the main battery turrets knocked out? Again I think a situation where Carrier A has moderate HP damage but most of it's planes flying and Carrier B is almost unblemished but set out of port with barely any planes on deck... B should be what gets priority targeting for air missions.

Speaking to this: unless it was early war American or British carriers which cruised in independent formations rather than jointly as a battlegroup, it would be really hard to "target" a single ship. As the war continued, the benefit of multiple carriers "sharing" a ring of AA cruisers/destroyers and their accompanying CAPs became obvious.

I'd imagine that targeting should be focused on what the attackers can "see" rather than getting that nitty-gritty. From my reading, Japanese pilots (for example) didn't care what ship they were necessarily attacking, just that they attacked the ship... which is why those picket destroyers were really pummeled.
 
Here is a really good article on Carriers and doctrine from the US Naval War College. @podcat, please review this and other articles from the NWC to really get an understanding of naval warfare in the Pacific. https://www.history.navy.mil/conten...y/m/midway-sheer-luck-or-better-doctrine.html

I'd argue, with Midway in particular, there was a lot more than doctrine involved. If anything, I'd argue the steady progression of attacks that kept the Japanese force from being able to spot-and-strike, which was in many ways only possible because of Midway airbase, and because of what was, in some ways, deficiencies in US doctrine (using carrier's air group individually, rather than as a group), combined with some (iirc) indisciplined (but well judged) behaviour on the part of one of the US air groups, that enabled victory in this instance, combined with the huge advantage of the IJN starting the day with no idea they were going to have to face enemy carriers, that were the key factors.
 
@Axe99 the article actually mentions the US doctrine of Search vs the IJN doctrine of attack led to the defeat of the IJN, seems like the article supports your arguments. Again, I think PDX has not fully researched carrier battles in the pacific and is leaning toward Atlantic battles to base its naval engagement engine.
 
Would merit an increased priority for naval bombers. Likewise wouldn't any carrier with less than 25% of it's planes operational be equivalent to a battleship with the main battery turrets knocked out? Again I think a situation where Carrier A has moderate HP damage but most of it's planes flying and Carrier B is almost unblemished but set out of port with barely any planes on deck... B should be what gets priority targeting for air missions.

The thing is that fires, oil leaks or slow speed is what invites pilots. They won't know if parts of the ship is damaged in other ways or if the aircraft compliment is low if there's no visible damage or odd behavior which would make the ship easier to spot attack and an inviting target.
 
@Axe99 the article actually mentions the US doctrine of Search vs the IJN doctrine of attack led to the defeat of the IJN, seems like the article supports your arguments. Again, I think PDX has not fully researched carrier battles in the pacific and is leaning toward Atlantic battles to base its naval engagement engine.

Sorry to do a quick 'fly by' post earlier - I've had a quick scan of the article now, and there's no question that the deck park (combined with building the carriers to suit - so with enough avgas and munitions to be able to operate that many aircraft for any period of time effectively) was important. I suspect (but would need to read more myself - I'm going based mainly in Shattered Sword*) that the author has relied a little too heavily on Fuchida for its criticism of the Japanese search doctrine though (although there's no question there were flaws in Japan's search doctrine, but Midway isn't exactly a fair test of the two navies, given the US knew Japanese would be coming and had oodles of long-range aircraft from Midway supplementing the carrier search aircraft).

I definitely think doctrine was important, but Japan at this stage in the war had a number of doctrinal advantages as well (some of which are well mentioned in the article) which are under-emphasised (as they have to be, for the author to make the argument they're making). On balance, I'm not convinced that at this stage in the war Japan had substantially better overall doctrine in terms of carrier warfare, and the article feels a little post-hoc rationalisation, and in my (quite likely flawed) view, I still think the dribble of strikes keeping the Japanese forces off balance (arguably a weakness in doctrine that worked out well on the day), intelligence, the extra strikes from Midway, and luck falling on the side of the US were the key factors. I could be wrong though, I don't work at the Naval War College, so I wouldn't be quick to rule out the author being on the money :).

As for carrier battles in HoI4, we'll see before too long hopefully :).


* Which, to be fair to the author, wasn't published when he wrote this article, so if they didn't have access to the Japanese sources that Parsons and Tully did, would have been at a disadvantage here.
 
This new system sounds like a huge improvement over the older one! But will we be able to set the posture/doctrine of our fleet though, e.g. Keep our fleet at standoff distance and let naval aviation do the work like in Midway/Philippine Sea, or aggressively advance with the enemy like the Japanese wanted? Or are we still going to continue to smash fleets together like in WoWs?
 
Will their be an option to assign certain ships that might normally be put in the first two lines to the third? IE minesweepers, seaplane tenders, and dedicated AA & ASW ships made from destroyer and light hulls.