Decoy Launcher

Decoy Launchers are player-designed components which were added in C# v2.2.0. They are similar to Missile Launchers, except that they fire decoy missiles and not normal missiles. Decoy missiles are intended to pull attacking missiles away from your ship, and trick them into attacking the decoy harmlessly instead.

Mechanics

Decoy missiles imitate ships of a size equal to (Decoy strength * 200 tons), so a size 10 decoy would imitate a ship of 2,000 tons.

Decoy launchers can be designed to fire decoys of sizes from 5 to 99, which imitate ships of sizes from 5 HS to 99 HS. A decoy launcher weighs 5 tons (0.1 HS) per point of decoy size, and costs 0.1 Duranium and 0.3 Tritanium per point of decoy size. This is the only selectable component for a decoy launcher - they are completely unaffected by technology (though the decoy missiles themselves are affected by missile ECM technology). They require no crew, and have HTK values from 0-4 depending on size. Decoy launchers may not be reloaded locally, and instead function like box launchers - they must be reloaded inside a hangar deck or at a maintenance facility.

Decoy missile effectiveness is reduced by enemy electronic counter-countermeasures. If their ECCM tech level exceeds your missile ECM tech level, then the effective size of the decoy is reduced by 20% per level of difference.

Example: A size 10 decoy at ECM level 3 against an enemy with ECCM level 5 would lose 40% effectiveness. This means its effective size would be reduced from 10*200 = 2,000 tons down to 2,000 * (100-40%) = 1,200 tons.

Because of their slow reload process, Decoys are only launched if the size of an incoming missile salvo is large enough. You choose what size of salvo justifies a decoy, by setting the Decoy Threshold value (using the button at the bottom of the Ship Combat tab of the F4 Naval Organization window). If an incoming salvo is believed to have missiles with total MSP at least as high as your threshold, then one decoy will be fired for each (threshold) MSP in the incoming salvo.

Example: If you have a threshold set to the default value of 50, and an incoming salvo has 180 MSP of missiles, then your ship will try to use 180/50 = 3.6 decoys, rounded down to 3.

Missiles will choose randomly between decoys and the actual target, based upon relative size.

Example: A 10,000-ton ship launches three size-10 decoys, with -40% effectiveness due to weak ECM tech. The total effective size of decoys is thus 1,200 * 3 = 3,600 tons, so the target plus decoys have a total size of 10,000 + 3,600 = 13,600 tons. Each missile has a 10,000/13,600 chance (~73.5%) of choosing the real target, and a 3,600/13,600 chance (~26.5%) of choosing a decoy.

In general, a decoy is only usable against a single missile salvo, and is then lost. However, if a specific decoy is not hit by any missiles, then it will stick around for subsequent salvoes. Once it is hit by at least one missile, it is removed.

Usage Notes

Notes up to date as of v2.5.1, released January 2024.

The total effective size of all decoys is added together, so 5 size-10 decoys are just as good as 1 size-50 decoy. The larger systems are also no more cost-efficient or space-efficient than smaller ones, and they reload slower. As such, there's really no advantage to a decoy launcher being large - the ideal size will almost always be 10, as size-10 launchers maximize HTK per ton, and are also small enough to give good flexibility in your designs.