In the case of the Pa'Mont-Class Battlecarrier, there are two possibilities. On the one hand, all the propulsion systems required for the space flight are removed and the ships are landed on a world in the ocean. There they serve as artificial islands. These can be used for military purposes by leaving all other military systems installed. However, by removing all military systems, these artificial islands can also be used for civilian purposes. Since the hangars of the Pah'Mont-Class, as with all modern carriers of this AU, correspond to the easily configurable SDUS concept, the hangars can easily be converted into hospitals, industrial plants or residential complexes once they are afloat. The simplest application is, of course, as a spaceport. Since the ships are now permanently on the water, which supports structural integrity, and materially demanding maneuvers in space are eliminated, the Pah'Mont-Class ships can be used in this way for decades to come.
You can see the second, purely military option here: the city-ships of the Colorado Springs Class.
Like every ship class, the Pah’Mont-Class ships must also be modernized and overhauled at regular intervals in order to remain both materially and technically operational. However, after 90 to 120 years of service, depending on the intensity of previous missions, the measures required for a general overhaul, modernization or repair are so extensive that it is more economical to recycle the old ship and build a new one.
The hyperdrive and the associated energy sources in particular must be replaced after 120 years at the latest, depending on the model and technology. For the ships that require such a "major overhaul", it is therefore always a difficult decision as to whether they should continue to be used or not.
When a Pah'Mont-Class ship reaches the age for a "major overhaul" and further repairs are required in addition to the overhaul, it is immediately taken to the depot for recycling. However, if the general condition of the ship allows that only a simple overhaul and modernization are required, the Pah'Mont-Class ship will be converted to the Colorado Springs class.
The hyperdrive, the ion drive systems and the external gravimetric drive (EGD) are removed from the ships intended for conversion, which is relatively simple and quick, as the installation of new drive systems is actually the difficult part of the construction work in a general overhaul. Next, the stern section is massively structurally reinforced to connect three Pah’Mont-Class ships together at this point. This is done by means of an "island construction" into which the stern sections of the spaceships are fitted.
The EGD attachment points of two Pah'mont-CLass ships are used to attach a structure known as an "engine clamp". This construction serves as a structural connection between "ship-island-ship" and to reinforce the outer structural integrity. The "clamp" also contain the sublight engine, as the ion engine located at the rear of the Pah'Mont-Class ships had to be removed at the beginning of the conversion work. The "engine clamp" consist solely of propulsion systems, power sources, control systems and structural reinforcements. There are no rooms for crew members to stay in, only three very narrow maintenance decks. Also to protect these structures, which are important for the overall structural integrity, they are armed on top with additional turrets
The resulting Colorado Springs Class has a size of 1702.4×1961.8×249.4 m and thus comprises the hangars of the three former individual ships (equipped in practice with 72 squadrons of various fighter, bomber and escort vehicles, all in all 384 fighter etc.), their armament and the additional armament of the "engine clamps". This means that the Colorado Springs Class is more heavily armed than the sum of its individual parts.
The Colorado Springs-Class is used as a defense facility, to secure allied territories, as a replenishment facility and for space surveillance. All tasks for which the much larger Dakara-Class city ships were originally designed. But the Dakara-Class was/is technically too advanced, too large and too complex, so that these ships cannot be built in large and therefore sufficient numbers even with the production possibilities in 400 years.
@Support Done!
this one is perfect Chris 
