Nice. This seems to be different from other places and the wiki that list a PDC component as 'one cargo hold'.
In PDC construction, 1 section size is equal to 2500 tons. Ie, if you design a 2499 ton PDC, it says its one section. If you design a 2501 ton PDC, its says its 2 sections.
Now, on the shipping side of things, a player now finds out that it takes a big 25,000 ton transport with 5 cargo holds to transport that one 2500 ton PDC prefab section. I can see a 2500 tonsection taking 5000 ton of cargo space as a prefab 'kit'. But it seems to be a bit of a stretch to say that this 2500 ton pdc section needs 25,000 ton, all on one ship, and that the unit is apparently such a massive one-piece unit that it can't even be divided between ships. If you saw the simple little passive-sensor only PDC that I'm trying to ship, this would seem really funny. Its two 250ton passive sensor units, plus enough crew qts and stuff for the operators. Well, let me copy it over here. Read this, then see if it makes sense for it to need 25000 ton of continuous cargo space on one ship.
PDC - Passive Sensor Post class Planetary Defence Centre 750 tons 60 Crew 100 BP TCS 15 TH 0 EM 0
Armour 6-7 Sensors 30/0 Damage Control Rating 0 PPV 0
Thermal Sensor TH5-30 (1) Sensitivity 30 Detect Sig Strength 1000: 30m km
EM Detection Sensor EM5-30 (1) Sensitivity 30 Detect Sig Strength 1000: 30m km
This design is classed as a Planetary Defence Centre and can be pre-fabricated in 1 sections
Well, thanks at least for this forum post that explains the answer as to why I can't load my simple little sensor PDC onto any of my 5kt cargo ships. Someone should sticky this info, or stick into an FAQ or something until the rest of the info catches up with these rules.
Early in the game, this matters as now it appears that not only do I need to move up from 5kt to 25kt transports, but that I've got to build the shipyards that can build them and the jump gates that can fit them, all to say I want to move a couple of passive sensors to another system and drop them on a rock.