Mortar

For additional guidance, see Defense structures and Weapon Guide.

The Mortar is a manned Security building similar to a turret. It launches mortar shells at targets outside of a minimum range (~30 tiles), either automatically targeted by the manning colonist, or manually targeted by the player. The effects of the mortar depend on the shell loaded.

Acquisition

Mortars can only be constructed once the Mortars research project has been completed. Each mortar requires 50 Stuff (Metallic), 1 Reinforced barrel, 6 Components, 2,000 of work, and a Construction of 5. If the Classic mortars storyteller option is enabled, the removal of reinforced barrels changes this recipe instead to: 75 stuff (Metals), 150 steel, and 6 components.

Alternatively, they can be claimed and taken from Sieges once all the raiders have been killed.

The mortar shells required to use the mortar must also be acquired separately. See their respective pages for details.

Summary

Mortars, when manned by a pawn, launch mortar shells one at a time at any enemy that enters its 500-tile firing radius, or at a target set by the player inside this radius. The player can target a location or a specific pawn. Regardless of the type of targetting, the mortar cannot fire at targets within its 29.9 tile minimum range. The displayed range indicator of mortars is not its range, but instead the size of this minimum range. Mortars cannot fire if covered by a roof. Firing can be toggled with the "Hold Fire" widget.

Mortars require a pawn to load and fire shells. Pawns incapable of violence will refuse to man them. Unlike drafted colonists, mortar personnel do not return to their normal schedule when undrafted and must be manually relieved from the mortar job.

Mortars have a forced miss radius of 9 tiles, i.e., the shell will land somewhere within 9 tiles of the designated tile. This radius is then multiplied the pawn's Mortar Miss Radius Multiplier, which in turn depends on the Shooting skill, and the Manipulation and Sight capacities. For more detail, see the Mortar Miss Radius Multiplier page. This base miss radius is increased to 13 if the Classic Mortars storyteller option is enabled. It is currently unclear if the pawn's radius multiplier applies when Classic Mortars is enabled.^{[Fact Check]}

It has a 240 ticks (4 secs) warmup time and a 1,680 ticks (28 secs) cooldown. Note that the cooldown does not tick down while no pawn is manning the turret, even if they are in the process of retrieving another shell.

Every 20 shots, a new reinforced barrel is required to rearm the mortar and allow continued firing. This requirement does not exist, and reinforced barrels are removed from the game entirely, if the Classic mortars storyteller option is enabled.

The effect on target depends on the type of mortar shell loaded into it. These shells can be manually extracted from the mortar. Mortars can be set to only accept specific types of shells at will. A summary of available shells is provided in the table bellow, but see the relevant shell pages for full details.

Mortar shell	Damage Base	Damage Type	Blast Radius	Market Value Base
Antigrain warhead	550	BombSuper	14.9	1,200
EMP shell	50	EMP	8.9	55
Firefoam shell	0	Extinguish	5	55
High-explosive shell	50	Bomb	2.9	55
Incendiary shell	10	Flame	2.9	55
Smoke shell	0	Smoke	7.2	55
Tox shell				26

If it is damaged below one third of its hitpoints, or 60 HP, it has a chance^{[What chance?]} to explode. The mortar will spark and emit a hissing sound shortly before exploding 240 ticks (4 secs) later. The explosion deals 50 Bomb damage in a 4.9 tile radius centered around the tile covered by the mortar closest to the interaction spot - that is, the explosion is not centered on the true center of the 2x2 mortar.

When hit by an EMP from any source, mortars are prevented from firing and the reload countdown is paused for the duration of the stun. Mortars do not 'adapt' to EMP. If an EMP attack does more EMP damage to a mortar than its remaining HP, the mortar will explode. For most sources of EMP damage, this is below 50 HP.

Analysis

Mortars are too inaccurate to target moving enemies, except when targeting large, dense groups or when using antigrain shells. Instead, they're better suited against sieging enemies, preparing raiders, and mech clusters . Note that Mech high-shields will block mortar shots and, if present, can render mortars ineffective against clusters, however the use of EMP shells will temporarily disable the shield. The shield will not be down long enough for a the EMP-firing mortar to load a shell and fire again, but a single EMP-firing mortar and several HE-firing mortars can work in tandem to attack the shielded clusters during the vulnerability by firing the EMP slightly in advance of the HE rounds.

Enemy sieges typically spawn with 2 mortars, that will be constructed by the enemy, and then fired at your base. Shells fired from mortars will break through constructed roofing but not through mountains (or any tile underneath one). Following a siege, it is possible to loot mortars from siege attacks, so long as the enemy builders complete construction, by reinstalling them in your base. Pawns assigned to construction will haul them to their new location.

Mortar pits

A full featured, if not necessarily optimal, mortar pit

Mortar pits are constructions used to facilitate rapid loading and firing of mortarts, store ammunition protect them and their ammunition from counter-battery fire and raiders, and/or protect the surroundings from any detonations of the same. At its simplest, a mortar pit might simply be mortar and a shelf for the shells to keep them close at hand and prevent deterioration. Additional features can be added as wanted or needed.

As mortars must be constructed outside, they are inherently at risk from counter-battery fire from enemy siege mortars and mechanoid automortars. Additionally, being explosive themselves, the shells and the mortars being attacked or damaged means they pose a risk to nearby structures. If mortars are placed together, one detonating can cause a devastating chain reaction and destroy the entire battery. However, due to explosion mechanics, any one explosion can be outright stopped by a single-tile-thick wall, even if the wall is destroyed in the process. Thus, seperating explosive items from each other by a single thick wall is sufficient to prevent most chain reactions. However, if two or more explosions occur non-simultaneously, the first explosion may destroy the wall and while the latter explosions damage items beyond it. This can occur if items are stored together, if whatever causes the detonation damages the wall itself, or if the cause of the detonation is able to damage two or more secondary explosives at the same time.

Unlike every other known instance, pawns that are loading mortars will not draw shells on a shelf from an adjacent tile, instead they will walk on top of the shelf to retrieve one. It is unknown if this is a bug or intended behaviour. Thus, the shelf trick does not cut down on walking times for mortar crew and in fact increases it, as the shelf has a path cost of 50. Shelves retain their utility in keeping items stored outdoors from deteriorating.

Stats table

Mortar	Beauty	Work to Build	HP	Flammability	Market Value
Material	Beauty	Work to Build	HP	Flammability	Market Value
Bioferrite	-20	005,000 ticks (1.39 mins)	360	52.5%	845
Gold	0	001,800 ticks (30 secs)	108	28%	5,800
Plasteel	-20	004,400 ticks (1.22 mins)	504	0%	1,260
Silver	-14	002,000 ticks (33.33 secs)	126	28%	1,300
Steel	-20	002,000 ticks (33.33 secs)	180	28%	895
Uranium	-20	003,800 ticks (1.06 mins)	450	0%	1,105

Image gallery

Plan grid: Mortar sits between 4 tiles
Manning a mortar
Setting a forced target

Version history

0.5.492 - Added as the Incendiary Mortar and Explosive Mortar
0.6.532 - EMP mortar added.
0.9.722 - Now requires shells to fire.
0.17.1546 - Buffed so players use them: Cheaper/faster to build, faster shooting, greater accuracy, cheaper shells.
Beta 18 - the three types of mortars (Incendiary, EMP and explosive) were replaced with a single type, which fires different types of shells that achieve the same effect. In addition, two new shells are added, the firefoam shell and the antigrain warhead.
1.1.2618 - the cost was increased from 100 steel, 50 materials and 4 components.
1.3.3066 - Mortars now require uncraftable reinforced barrels to build and rearm after every 20 shots. Forced miss radius lowered from 13 to 10. All craftable mortar shells have had their crafting recipes lowered by 10 steel. Recipe changed from 75 stuff, 150 steel and 6 components to 50 stuff, 1 reinforced barrel, and 6 components. All changes are reversible in the "Classic Mortars" storyteller option.
1.3.3067 - Mortars don't drop their barrels when deconstructed if under 50% "fuel" i.e. after 10 shots have been fired with that barrel.
1.3.3200 - Forced miss radius reduced from 10 to 9. Mortar accuracy now varies by its crewman's Mortar Miss Radius Multiplier. Previously nothing but the Classic Mortars option affected mortar accuracy. Uninstalling and reinstalling a mortar no longer resets its cooldown.

Sprite of the EMP mortar before merge
Sprite of the Incendiary mortar before merge

Architect

Security: Barricade • Sandbags • Spike trap
(research): Autocannon turret • Foam turret • Mini-turret • Rocketswarm launcher • Uranium slug turret • Mortar
IEDs: IED trap • IED incendiary trap • IED EMP trap • IED firefoam trap • IED smoke trap • IED antigrain warhead trap • IED tox trap
Related: Antigrain warhead • EMP shell • Firefoam shell • High-explosive shell • Incendiary shell • Smoke shell • Tox shell