Morale/Fatigue is a hidden statistic within the game. Each ship has their own morale value. It ranges from 0 to 100 and has various boosts and penalties associated with it.

Morale Fatigue 

Fatigue occurs at low morale. Ships with enough rest will have a morale value of 49. A value above 50 is commonly known as the "sparkle" effect.

Morale regenerates at 3 points every 3 minutes (like fuel, steel and ammo) and this automatically regenerate until 49.  After 4/23 update, Morale now regenerates, upon return to base, for time spent on a sortie.   Operates under same conditions as normal regeneration.

Indications

Below are the indications of your ship state. Specific effects will be explained below.

Morale value Indication Ship State
≥50 The image of ship generates sparkling effect. High Morale
49~40 Ships are in their normal state. Normal
39~30 Ship looks normal, but the "Mamiya Food Ship" button in Organize/編成 page is flashing. Slightly Fatigued
29~20 An orange smiley face is shown by your ship image in the Organize/編成 page. Moderately Fatigued
19~0 A red smiley face is shown by your ship image in the Organize/編成 page. Seriously Fatigued


Effects

Morale value Effects
≥50
High Morale
  • [Sortie] Improved evasion and accuracy during battle.

  • [Expedition] Higher chance of great success in expedition.

  • [Expedition] Higher chance of triggering support expedition

49~40
Normal
  • Normal state - no effect on performance/special effect.
39~30
Slightly Fatigued
  • [Sortie] Slightly decreased evasion and accuracy.
  • [Expedition] Expedition will fail if your fleet returned in this state.
29~20
Moderately Fatigued
  • [Sortie] Decreased evasion and accuracy.
  • [Expedition] Expedition will fail if your fleet returned in this state.
19~0
Seriously Fatigued
  • [Sortie] Severely decreases evasion and accuracy.

It is only possible for a ship to sink if it enters the battle node at heavy damage; Morale does not have a direct role in this.  However, Moderately/Seriously fatigued ships suffer severe penalties that are exacerbated with longer sorties.  It is high inadvisable to sortie them unless you are only farming one node and/or do not care about performance.

Morale modifiers

Below is a table of morale modifier in terms of morale value. +10 morale = -10 fatigue  Morale has a maximum value of 100.

Type Action Morale Modifier
Sortie/PVP Obtaining MVP in a battle +10
Sortie/PVP Entering battle as flagship of a fleet +3
Sortie/PVP Entering a battle starting with night battle +1
Sortie/PVP Obtaining Battle Rank S/Perfect S +1
Sortie/PVP Obtaining Battle Rank A ±0
PVP Returning from a PVP battle ±0
Sortie/PVP Obtaining Battle Rank B -1
Sortie/PVP Obtaining Battle Rank C -2
Sortie/PVP Obtaining Battle Rank D/E -3
Sortie/PVP Entering night battle -3
Sortie/PVP Entering battle with morale less than 30 -6
Expedition Returning from normal expedition -3
Expedition Returning from Support Expedition #33 -1~5
Expedition Returning from Support Expedition #34 -1~10
Sortie Returning from a sortie -15 
Other Newly constructed a ship morale starts at 40
Other Ship obtained from sortie morale starts at 40
Other Remodel a ship morale resets to 40
Other Docking repair completed reset to 40 only if morale is 0~39
Other Using Mamiya Food Ship case 1 reset to 40 if morale is 0~39
Using Mamiya Food Ship case 2 reset to 50 if morale is 0~49
Other Morale natural regen +3 morale per 3 minutes, until reaching 49

It takes about 20 minutes to go from absolute zero to orange and another 10 to go from orange to normal.

Gaining morale with maximum efficiency and minimum cost

Running 1-1 solo

Use Maruyu as meat shield for flagship, she can't MVP since her torpedo stat is horrible and 1-1 is only DDs so flagship wont take damage, even if maruyu gets broken, the repair time and cost is very low.

By doing a World 1-1 full run, your flagship will have a net morale gain of +13.

Assume that your flagship obtained S rank MVP in both nodes, and did not enter any night battle, it will be as follow:

New morale value

  • = X +10 + 3 + 1 + 10 + 3 + 1 -15
  • = X + 28 -15
  • = X + 13

However you won't always be able to finish both battles with S, especially when you hit the boss node. And the flagship has a risk of getting seriously damaged if her level is low. Therefore it is recommended to send one or two level 1 DDs with her. Additionally, you can remove the equipments to prevent them from getting MVP and choose to not resupply or repair them, and then use them for modernization or decommission after getting damaged or went up to level 2. Avoid night battles in most cases. Going from B (-1) to S rank (+1) would not change the final rating. Only when you're at C or D rating and know you can hit A or S it is advisable to go into night battle. If the flagship couldn't obtain MVP, you can repeat the same process to get her sparkle.

Just doing the first node will result in -1 morale, even if you perfect S rank it without a night battle.

(-15 + 13 + 1 = -1)

Thus in most cases you should proceed to second battle unless any of the ships is heavily damaged.

Day Battle S Victory in Exercises

By obtaining a battle rank S in exercises without entering night battle, your flagship will receive a morale gain of +4, while your consort ships will receive a morale gain of +1. The MVP of the battle will receive an additional +10.

If your ships are fully rested and have a morale of 49, by obtaining the +1 morale from battle rank S their morale will become 50, which produces sparkle effect. This can be useful for giving the sparkle effect quickly to ships for one long expedition.

If you enter night battle or only achieve A rank, only the flagship and MVP will receive a morale boost.