Hearts of Iron IV Hearts of Iron IV

In this guide I will try to explain as best as possible how navy works.

Convoys

Convoys have different priorities based on the "job" they are assigned to.

Naval invasion or transferring troops through sea
Supplying remote units outside of mainland
Lend lease
Trade
Internal resource trade

With 1 being the highest priority and 5 the lowest.

Additionally the furthest the selected target for the convoy to reach, the more convoys it will require. For example trade for Cuba costs less convoys with USA in comparison with USSR due to the distance between the target countries and Cuba. Confused yet? you haven't the rest yet :^)

Important Ship Stats

Max speed = It's the max speed a ship can have. Ships with high speed values can dodge more shots, move faster, retreat and engage faster.
Max Range = basically how far a ship can go (you can extend this by asking for docking rights)
HP = How much damage the ship can take before it gets destroyed.
Organization = If it runs out, your ships get heavy debuffs. Organization runs out by moving to other sea tiles, engaging into battle or exercising the fleet.
Armor = The armor value that ship has. Having higher armor than the light/heavy piercing of the enemy ship will result in reduced damage taken as well as more attacks per hour. Having less armor will result in bigger damage values taken.
Light Attack = It's the attack capability of a ship towards a non capital ship (more on non capital ships later)
Light Piercing = The armor value that the light attack can pierce.
Heavy Attack = It's the attack capability of a ship towards a capital ship (more on capital ships later)
Heavy Piercing = The armor value that the heavy attack can pierce
Anti Air = The air attack a ship has towards planes
Depth Charges = Damage done exclusively to submarines
Torpedo Attack = The torpedo damage a ship can do to a target (can't hit enemy submarines)
Surface Detection = How easy spotting enemy ships is for your ship, the higher value the better (ships with high surface detection get more hits on enemy ships)
Surface Visibility = How hard is for the enemy ships to spot your ship (the lower the better)
Sub Visibility = How easy it is for your sub to be detected (the lower the better)
Sub Detection = How easy it is for your ships to spot subs (the higher the better)

Ship Types

With 1.7.0 ship priority fire has changed and it goes like this: Carriers engage the battle first, after some hours battleships engage and at last the rest ships.

The ships are split into two categories, capitals and non capitals.

Non Capitals (screens):

Destroyers
Light Cruisers

Capitals:

Heavy Cruisers
Battle Cruisers
Battleships
Super Heavy Battleships
Carriers

However, there is only one cruiser hull. So how can you make a light/heavy cruiser you ask? That's simple. If you have medium batteries (heavy cruiser batteries) on your cruiser hull it will count as a capital (heavy cruiser) or if you use light batteries it will count as screen (non capital).

Here is an example of a light cruiser (this is only for showing purpose I will get to some templates later.

And here is an example of a heavy cruiser.

See that "gem" that I higlighted? That basically says if your cruiser is considered capital or not.

Ship Templates

These are some templates I found out that were pretty useful.

Carriers - 1936 Carrier Template.

Carriers - 1940 Carrier Template.

Fleet In Being Doctorine

In Hoi4 there are 3 types of doctorines for navy, one capital focused , one raiding focused and one carrier focused.

Fleet in Being is the battleship focused doctorine and provides a lot of buffs for your capital ships, more in depth stats:

Capital Armor +10%
Capital Ship Attack +10%
Naval anti-air attack +10%
Battleship organization +60
Battlecruiser organization +40
Heavy cruiser organization +50
Destroyer organization +20
Destroyer surface detection +10%
Destroyer submarine detection +10%
Carrier organization +30
Sortie efficiency +30%
Light cruiser organization +10
Light cruiser submarine detection +10%
Light cruiser surface detection +20%
Strike Force organization loss -20%
Escort efficiency +5%

While going the middle path provides (escort focused path):

Destroyer submarine detection +20%
Destroyer organization +40
Light cruiser organization +10
Light cruiser submarine detection +15%
escort efficiency +40%
Carrier submarine detection +25%

Lastly Right path (submarine focused path) gives:

Submarine Surface Detection +25%
Submarine raiding efficiency +15%
Submarine organization +40
Torpedo reveal -15%

Trade Interdiction Doctorine

Convoy raid/torpedo buff research tree.

So going left side gives:

Submarine Surface detection +5%
Submarine organization +10
Light cruiser surface detection +15%
Light cruiser surface visibility -10%
Light cruiser raiding efficiency +15%
Light cruiser organization +20
Heavy cruiser surface detection +15%
Heavy cruiser surface visibility -10%
Heavy cruiser raiding efficiency +15%
Heavy cruiser organization +30
Battlecruiser surface detection +15%
Battlecruiser surface visibility -20%
Battlecruiser raiding efficiency +15%
Battlecruiser organization +30
Battleship surface detection +25%
Battleship surface visibility -25%
Battleship raiding efficiency +50%
Battleship organization +50
Capital ship Armor +10%
Enemy fleet size penalty +10%
Strike force organization loss -20%
Carrier organization +20
Sortie efficiency +20%

Middle path gives (carrier focused tree):

Carrier organization +40
Naval targeting +20%
Destroyer submarine detection +5%
Destroyer organization +10
Escort efficiency +5%
Sortie efficiency +10%

Right focused tree gives (sub focused):

Submarine Surface detection +45%
Submarine raiding efficiency +50%
Submarine attack +10%
Submarine organization +40
Torpedo reveal chance -25%
Submarine HP +20%
Light cruiser surface detection +15%
Light cruiser raiding efficiency +35%
Light cruiser organization +10
Heavy cruiser surface detection +15%
Heavy cruiser raiding efficiency +35%
Heavy cruiser organization +10
Battlecruiser Surface detection +15%
Battlecruiser raiding efficiency +35%
Battlecruiser organization +10

Source: https://gameplay.tips/guides/4562-hearts-of-iron-iv.html

Hearts of Iron IV - Navy Guide