Is there a GW Definition for a Space Hulk?

Is this a large mass of floating junk (former ships) that have somehow managed to come together?

I remember the old game.. with the genestealers.

I remember the computer game.. and in both cases you are aboard a derilic type ship.. but HULK? what is the fluff behind this being a mass of ships?

Do these form after massive battles within a system and they are drawn together because of the gravity etc???

Thanks.. know it sounds silly, but I see it refered to in histories as the space hulk called...... etc..etc.. and I wonder how did trash get a name? can it fly? is it powered somehow??

It is a floating ship wreck. Could be one ship or several which have drifted together in warp eddies or gravity wells. There is a really big one in Purge the Unclean for Dark Heresy (I think its PTU). It is made up of lots of ships.

What puzzles me is reading histories, and hulks get names, and they are involved in events, I am just wondering what defines something as a Space Hulk and not just floating junk?

thanks

Lexicanum, because it's right far more often than it's wrong and I can't be bothered typing out the same thing with less elloquence and more spelling mistakes:

A Space Hulk is a massive conglomeration of lost ships and wrecks fused together. They drift in and out of the warp through space and during the millennia the lost ships join together into one enormous body. Many times they are so huge that they have their own atmosphere and gravity. Since the hulks often exit and re-enter the warp seemingly at random, searching or traveling in them is dangerous in the extreme.

The Imperial Navy, and all Imperial forces and authorities as a whole, have standard orders to survey such objects and to report their location. The hulks consist of ships and items of technology millennia old, and the recoverable technology can be of immense value to the Imperium, and especially to the Adeptus Mechanicus. Thus elite Imperial forces are sent aboard to clear out infestations. Depending on the strategic situation (availability of troops, proximity to vital Imperial star systems, safety margins, etc) Space Marines are sent to purge the hulk of any alien infestations.

Space hulks are dangerous, as many times they are used as means of transport by certain unsophisticated factions. The Orks, the Genestealers, and the Chaos renegades use them occasionally to invade other worlds. As the warp jump of Space Hulks is essentially made in a random direction this gives them advantage of surprise.

Therefore the mission of boarding space hulks is extremely dangerous and normally entrusted to Terminators, the Chapters most experienced elite who are heavily armed and armored. In some cases this is an impossible task, due to too powerful enemy resistance, too few available Imperial troops, too close to vital systems, etc. In such cases the bombardment and total destruction of the Hulk is the only viable alternative.

Space Hulks are huge and durable, as even Nova Cannon blasts aren't enough to take one down.

Due to the peculiar nature of the warp lost ships are often pulled together and fused, often with still living crews. These fused forms are called Space Hulks. For whatever reason they seem to drift in and out of the warp, perhaps due to still functional malfunctioning warp drives or perhaps because of their affinity to the warp.

Space hulks are considered a virtual gold mine because of the ancient archeo and xeno technology they often contain. Even just grabbing a few important looking pieces can make a man wealthy beyond their dreams. Successfully reclaiming an entire hulk could reward those daring enough to attempt it with the wealth of worlds. So valuable is a reclaimed hulk that entire SM chapters and Rogue Trader dynasties will dedicate years and thousands of lives to accomplishing such a task. Of course with such wealth on the line the risks are equally legendary.

Space hulks usually (though not always) have "passangers". And even if no one actually attempts to venture aboard a space hulk there is still reason to worry. A new Space Hulk appearing can threaten entire planetary systems. Tyranids and Orks seem to favor loading up on space hulks as impromptu warp vessals to launch suprise attacks on whatever hapless system the hulk appears in. Daemons are also know to be able to ride a hulk back into real space.

Even when ships are recovered from a Space Hulk they are said to always carry some taint of the warp with them having spend so much time as a denizon of the immaterium.

Hulk is used in 40k for any crippled ship. So it could be part of a ship, a ship, or a huge mass of ships. Orks will often use large hulks as battleships. As will some Chaos types.

There also appears to be a class of Hulk formed by ship lost in the warp. These ships seem to be drawn into the warp, spit out, hang out for a while, and then pulled back into the warp. These are often used as transport by Orks, and what not....