What to do With Old Ships

[Borealis4x (OP)]

What should I do with old, outdated ships? I would like to sell them to my civilian industry so that they can offer more robust services, but I don't think I can. Is there a way to decommission them and get some resources back without needing a salvager?

[Iranon]

You can scrap them at shipyards.
Or you can mothball them by shoving them into a hangar PDC, this avoids any running costs.

[MarcAFK]

You have 2 options which will give back some resources, oddly each option gives back different intact systems or actual resources.
Option one is to abandon and destroy the ship, then salvage the wreck, The option should be on the individual ship window, make sure it's not carrying important officers or whatever. You'll get some resources and several random systems back when you send a salvager. The other option is to send it to any shipyard and then there will be an option to scrap it at the shipyard window. The shipyard does list resources for scrapping but ignore what it says, you actually get nothing back from scrapping, but you'll recover most of the ships systems, I'm not entirely sure what but not everything, definately engines are recovered though. I'll see if I can see the thread where I posted this as a bug report, it's intended to work this way though.
EDIT:
TLDR with scrapping you'll get back drives, fire controls, missile launchers, beam weapons. No sensors, or magazines.
For reference here's the post in question.

Off-Topic: show

I'm surprised nobody has noticed this one: Scrapping doesn't return any minerals: just recovered components.
I figured this was the intended behavior untill I made my first salvagers and noticed significantly more minerals being recovered.
When a vessel is added to the scrap queue there is a list of minerals that I assume should be recovered, however you get instead a pile of components, which when scrapped returns completely different quantities of minerals, in some cases more than what was listed, but generally much less.
For a ship that is entirely armour you get nothing returned at all. Interestingly destroying the ship and salvaging recovers  slightly more minerals, though I suspect that only a small amount of components survive to be salvagable which affects the total, but in any event salvaging gives a pile of all minerals immediately, then some for components while scrapping just gives components, although more components are recovered.
Heres my test setup, I created 2 ships, one of each class will be scrapped, and one salvaged.
First a pretty standard missile ship. Actually a bit better in most respects than what I'm currently using in my game.
Tribal class Cruiser    8,500 tons     225 Crew     1147.35 BP      TCS 170  TH 510  EM 0
3000 km/s     Armour 3-37     Shields 0-0     Sensors 1/1/0/0     Damage Control Rating 4     PPV 36
Maint Life 2.17 Years     MSP 337    AFR 144%    IFR 2%    1YR 96    5YR 1440    Max Repair 240 MSP
Intended Deployment Time: 3 months    Spare Berths 0   
Magazine 336   

255 EP Ion Drive (2)    Power 255    Fuel Use 44.96%    Signature 255    Exp 8%
Fuel Capacity 695,000 Litres    Range 32.7 billion km   (126 days at full power)

Size 6 Missile Launcher (6)    Missile Size 6    Rate of Fire 90
Missile Fire Control FC128-R80 (1)     Range 128.8m km    Resolution 80

Active Search Sensor MR128-R80 (1)     GPS 19200     Range 128.8m km    Resolution 80

This design is classed as a Military Vessel for maintenance purposes

I think a table would be the best way of showing the data, but I'm not sure how to do that, so I'll just list the results.
Tribal: Cost of ship:
294 Duranium
5 corbomite
210 tritanium
52 boronide
48.75 mecassium
320 uridium
216.75 gallicite
Displayed Scrap value:
73.7 Duranium
1.3 corbomite
52.5 tritanium
13 boronide
12.2 mercassium
80 uridium
54.2 gallicite
No minerals were recovered. But the following components were: drives, sensor,magazine, firecontrol, missile launchers, fuel
After scrapping components we have the following minerals:
21 duranium
63 tritanium
96 uridium
65 gallicite
167 wealth.
Now salvaging instead gives the following:
29 Duranium
2 Cobomite
42 Tritanium
5 Boronde
24 Mercassium
23 Uridium
And these components: Drives, fire control, missile launchers.
Notably absent is active sensor and magazines, after scrapping we get:
9 Duranium
27 Tritanium
24 Uridium
65 Gallicite
125 Wealth
The total compares pretty well with the scrapped ship, except neither produces as much as expected from the scrap estimate.
Now a slightly different ship:
Armor ball class Cruiser    9,000 tons     1 Crew     10.4 BP      TCS 180  TH 0  EM 0
1 km/s     Armour 28-38     Shields 0-0     Sensors 1/1/0/0     Damage Control Rating 0     PPV 0
MSP 0    AFR 1800%    IFR 25%    Max Repair 6 MSP
Intended Deployment Time: 3 months    Spare Berths 2   


This design is classed as a Commercial Vessel for maintenance purposes
The Armour ball is literally nothing but 28 layers of armour and a tiny crew quarters. (That officer must feel pretty safe) Therefore it costs only .75 mercassium and over 1079.65 Duranium, nothing else.
Displayed Scrap value is:
269.9 duranium
mecassium .2
When scrapped no components or any minerals are recovered.
However when salvaged we get 216 Duranium in our cargo hold.
I'm sure what's intended is that whatever code is responsible for giving back minerals when salvaged should also be applied when a ship is scrapped, but in that case you would also get more recovered components and therefore have better returns....
Right?

[Borealis4x (OP)]

But I dont want outdated engines and fire controls

[MarcAFK]

You scrap the engines for gallicite and the fire controls for iridium. The component scrapping window is on the production screen.