I note that not all watch fortresses are void-based or even large enough to provide facilities for Deathwatch vessels to dock for repairs. I get the impression that the huge Erioch is an exception to the rule in size. There is also the issue that the Deathwatch can often be short of specialities such as techmarines thanks to brothers rotating out to their home chapters.

So the question arises of where do Deathwatch voidships get repaired? Must they find quiet systems and slowly be rebuilt away from prying eyes? Or do they have arrangments with other chapters to use their facilities? Or perhaps shielded and private docking arrangements on allied forge worlds?

I'm inclined to think that the Deathwatch will use any or all of the above, as the situation allows but prefer using their own men and material whenever possible.

Decessor said:

I think you answered your own question. No other answer comes to mind as being any more logical or reasonable than your conclusion.

One more thing I think you haven't mentioned is that the few watch stations large enough to dock the star ships would not close stop working for any reason. Regardless of actual battle brother presence there would be 10's of thousands of vassal workers the equal of anywhere in the Imperium and probably a Mechanicus contingent in somewhere the size of Erioch (the Astartes Foundries wouldn't have made the Ships themselves afterall).

If the Deathwatch is short on Techies, or they need a large number for a certain project, they will requisition them from the miriad of chapters. The techmarine's watch would last until the specific job is done then they'd return home.

Watch-captain: Curse those Xenos! Our ship is damaged! We don't have the facilities to deal with this!

Ordo Xenos Inquisitor overseeing the Deathwatch: I'll take care of it.

W-C: But the port weapons are gone, the reactor core is leaking, the bridge has been depressurised and - due to Gellar field flickers - the fluffy dice only have five sides each!

OXIotD: Shhh... I'll take care of it.

Go go gadget Inquisitorial privlege!

Duly noted everyone. Thanks for the opinions.