Thing for me is, I don't, as much, see the upkeep as a big slow down/speed bump for the players. What I might do, circuitous as it might seem, is find the first ship that would otherwise pick a fight with the HMS Darklight, pound on it a bit, to cover a boarding action for the Astartes, who, if Space Hulk is any indicator, excel at boarding actions, and fighting in cramped quarters, even against unknown quantities of foes, and then, claiming that ship as a spoil, leave the Darklight, still with plenty crew, mind, in a "safe place", perhaps in orbit over a nice world, and use the captured vessel to move less obviously, for scouting purposes. If this works, the upkeep checks become rare, as the Light of Terra maintained plasma, and some armament, for 2,000 years, while the Darklight might only need to account for a few, due to the temporal oops they suffered. If they were active during the Crusade, I also believe they would have their own Tech-Priests, not yet burdened by tech-amnesia so common among them, now, so fixing some systems would be doable.They could easily collect resources with that captured ship, from a few places, and thus in smaller quantities, allowing them to restock the Darklight, eventually, without ever having to take her into port. One of my ideas, ages ago, was for a potential group to find a battleship wreck, and once "salvaged", it was going to serve as a space station, of sorts (the motive drive and thrusters were beyond repair), if they could get it to a good, critical location, worth overseeing. It was partly a "here's a battleship" thought, coupled with the slowly rebuilding up the Necron Monolith, in DoW: DC, which I was playing, at the time, where the engines would be the last upgrade, if possible. I could easily see a group either send out lackeys to get stuff, or do that, and leave the lackeys guarding the battleship. It might take a little while, but things in this game just do, sometimes.

Yea, I'd just stick with giving them a Grand Cruiser at best, or a frigate at the least for such an "interesting" background concept.

Thing for me is, I don't, as much, see the upkeep as a big slow down/speed bump for the players. What I might do, circuitous as it might seem, is find the first ship that would otherwise pick a fight with the HMS Darklight, pound on it a bit, to cover a boarding action for the Astartes, who, if Space Hulk is any indicator, excel at boarding actions, and fighting in cramped quarters, even against unknown quantities of foes, and then, claiming that ship as a spoil, leave the Darklight, still with plenty crew, mind, in a "safe place", perhaps in orbit over a nice world, and use the captured vessel to move less obviously, for scouting purposes. If this works, the upkeep checks become rare, as the Light of Terra maintained plasma, and some armament, for 2,000 years, while the Darklight might only need to account for a few, due to the temporal oops they suffered. If they were active during the Crusade, I also believe they would have their own Tech-Priests, not yet burdened by tech-amnesia so common among them, now, so fixing some systems would be doable.They could easily collect resources with that captured ship, from a few places, and thus in smaller quantities, allowing them to restock the Darklight, eventually, without ever having to take her into port. One of my ideas, ages ago, was for a potential group to find a battleship wreck, and once "salvaged", it was going to serve as a space station, of sorts (the motive drive and thrusters were beyond repair), if they could get it to a good, critical location, worth overseeing. It was partly a "here's a battleship" thought, coupled with the slowly rebuilding up the Necron Monolith, in DoW: DC, which I was playing, at the time, where the engines would be the last upgrade, if possible. I could easily see a group either send out lackeys to get stuff, or do that, and leave the lackeys guarding the battleship. It might take a little while, but things in this game just do, sometimes.

So everything you say here is correct but makes my point for me! The players cannot just waltz in with their mighty battleship and start shooting their way through the campaign! At least not for long! While taking a vessel to use as a scout is certainly viable as an option. There are others as well. That's the point! But even your solution has some interesting Role-playing options... What happens when word gets out that a vessel was boarded by Space Marines bearing the colors of the Luna Wolves? How would the Inquisition react to that? (Bear in mind that at least initially, a 31st century Luna wolf captain would not sanction the "Kill everyone aboard" Idea!). Also remember that the Crew of the Oberon would not even know how different things are in the 41st millennium until they encounter an Imperial world or unit! So remaining completely unknown would be difficult.

This remind me of another idea I have; adding external weapon hardpoints onto frigates. So that for example the explorers could equip an (additional) lance with only a 15 ^o forward firing arc, or sixteen torpedoes that would require an extended repairs action to reload. To represent the compromised integrity from adding hardpoints to the ship weapons crit it on one lower than usual. What does everyone think of that?

This remind me of another idea I have; adding external weapon hardpoints onto frigates. So that for example the explorers could equip an (additional) lance with only a 15 ^o forward firing arc, or sixteen torpedoes that would require an extended repairs action to reload. To represent the compromised integrity from adding hardpoints to the ship weapons crit it on one lower than usual. What does everyone think of that?

The lance one feels like it would be impractical, given that the size of the average Imperial lance is not going to be shrunk down or miniaturized easily. The torpedo one sounds like it might be feasible, especially if it breaks every time you try to use it. A risky, but perhaps brilliant innovation that would enhance your ship.

You'll be burned as a Heretek if it ever comes out of course.

My idea was more along the lines of bolting lances to the hull so that they were fixed-forward firing, the extended repairs for torpedoes was less about repairing them and more about having the time to attach another torpedo to the recently vacated hardpoint ala missiles on aeronautica.

The problem with "bolting lances" is that a lance is not just the weapon mounting that hangs under the front of the ship, as with a Dauntless, or the turret that juts out of a cruiser's broadside, as on a Lunar. It represents a massive assembly hidden from view within the ship itself in the form of massive capacitors, projection arrays, heat sinks, etc.

Secondly, a frigate's plasma drive rarely has the necessary output to sustain a Lance weapon in addition to its already existing systems. Lances are incredibly power-intensive and adding one to a ship not designed for it could critically destabilize its central power grid, not to mention the loss in actual stability from the added weight of the Lance systems.