One thing to keep in mind, which someone sort of brought up. A space hulk has likely spent a lot of time in the warp, and even when it leaves the unreality of that realm might remain. Even simply things like the configuration of a component ship's corrirdors might be turned into some subconsciously maddening maze due to contact with the warp. Entire alien enviroments might exist deep inside them, even when 'real physics' says they can't exist. The aforementioned ice and snow is just the least worrisome of those results.

Parts would fuse together, 'things' would be seen skittering in the half light of your luminators, and if you don't hear the occasional distant scream of the damned then you're probably already screwed. Oh, also, demons, or things twisted into spawn are entirely possible.

Keep in mind that's when the thing isn't in the warp. If it's still there, or just came out I'd imagine you'd probably not even want to get within a sector of it until you're sure it won't drive everyone on board mad.

Imagine the most horrific elements of DOOM, Dead Space, and Pirates of the Carribean all packed into one massive complex the size of Rhode Island. Now, go and tell your crew that's their new clubhouse.

Event Horizon comes to min as an inspiration source too... The Imperium is afraid odf the warp for a reason.

Another problem with space hulks is their habit of randomly returning into the warp. Few peoples ar wliing to dump years of reffiting into one to see it disappear before it's finished, taking a lot of expereienced tech-priests along for the ride.

Errant said:

First thing, they broke with the Imperium because they were, for simplicities sake, mugged.

• Their Chapter Relic was taken by the Machanicus.
• They merely held the Orbital the Administratum wanted while they tried to negotiate its return.
• They were then attacked by said same Mechanicus bastard who mugged them.
• For defending themselves they were declared Excommunicate with the Inquisitor not even being willing to consider he himself had been lied to about events.
• There was then a Duel amongst the Chapter Master and Sarpedon, not the brightest of Souldrinkers. Sarpedon the Emo Librarian won.
• Prior to their recruiting of more Neophytes, the remnants of the Chapter were still loyal to the Emperor and Mankind in general, but not the corrupted Imperium that had replaced the Emperor's vision.

Honestly, having read a good chunk of the 40K material (novels and gaming books) I rather enjoyed their reason for going renegade more then, say Lugft Huron's and his Astral Claws reasons. " Hey guys, I'm bored. Let's go be pirates! "

Errant said:

Pretty sure that, per the novels, the Souldrinkers did not have an actual Fortress Monastery until they scuttled their fleet and took to the Brokenback . Prior to that, I believe it was said that they had two Battle Barges and a smattering of Strike Cruisers. I do not recall mention of any escorts in the books.

-=Brother Praetus=-

The new Forge world books covering the Badab War actually flesh out the whys of the Astral Claws turn to renegade. In many ways it's more interesting than the soul drinkers reasons.

And just to keep it on topic there's a space hulk that played a part in the slow fall from grace that afflicted the marines in the Badab sector. It was basically a space hulk that had somehow become a mobile real space capable daemon transport which drove everyone within a star system mad as it drew closer. Only the lamenters proved capable of attacking and boarding it and even they lost about a companies worth of their brothers doing it.

They were then censured for not getting the job done faster by imperial bureaucrats who weren't even involved in the area's defense. Needless to say, they did not approve of this response to their valor.

But there's another reason space hulks are feared, some of them become miniature daemon worlds after long exposure to the warp. Kind of like that one ship in Creature's anathema, only the size of a small moon, or big battlestation.