Forum adverts like this one are shown to any user who is not logged in. Join us by filling out a tiny 3 field form and you will get your own, free, dakka user account which gives a good range of benefits to you: No adverts like this in the forums anymore. Times and dates in your local timezone. Full tracking of what you have read so you can skip to your first unread post, easily see what has changed since you last logged in, and easily see what is new at a glance. Email notifications for threads you want to watch closely. Being a part of the oldest wargaming community on the net. If you are already a member then feel free to login now.

#1 How long can a astartes live for:
I know there are some astartes have lived for quite a while, but how long can a astartes live until he dies?i know the adeptus custodes live more than 10 millennia for protecting the emperor and all, but is it possible to have a chapter master to live that long?

#2 what current chapters are the most friendly to new chapters: are there ant chapters that would be most likely to team up with or aid DIY chapters?


#3 what is the most accurate number of ships in a fleet base chapter? : so far i've heard that its possible to have 1-3 battle barges, 3-5 battle ships, 6-12 strike cruisers, 50+ frigates/destroyers, 200+fighters and a TON of drop ships

#4 can my chapter master have a lightning claw in the same style as "the talons of Horus"? can something like that be commissioned to the mechanicus?

#5 can space marines have chainaxes ?

#1 No one know!!!!
Most die before old age takes them, and if they have lived long enough they will probably be thrown into a dreadnaught, bajorn has been around for 10,000 years in his walking toaster box.

#2 If by friendly you mean most willing? Probably the ultra marines.

You could always be one of the super independent totally no a super secret chapter of the dark angels that only exists because our chapter was getting to large and we wanted to keep our numbers but not make it look suspicious, heh, heh, heh.

#3 your numbers are a little off, its a lott less then that. ill need to find my dark angels book to give you an idea of the numbers

#4 I dont think anything would stop you? But its traditionally a heretic weapon.

#5 technically yes, probability? No, they probably dont have the SCT for it.

1) Dante is the 'oldest living chapter master' and is about a thousand years old. The Blood Angels are long-lived even by marine standards though. Generally 'several centuries' - expect a marine veteran, captain or other officer to be 500 years old plus.

2) Most likely; ones who share common ancestry. There are only nine loyalist gene-seed 'strains', each descended from one of the loyalist legions, and every chapter existing today comes from one of them (or comes from a more recent chapter which in turn comes from one of them).

So the Red Space Weevils are a successor chapter (created in M.37) to the Beige Astral Aardvarks (Created in M.33) who are in turn successors to a little known Third Founding Chapter from the Imperial Fists. As a result, the chapter will have (broadly) the same chapter cult as the fists - but a couple of times removed. Nevertheless, they'll get on better with other fists successors (the Imperial Fists themselves, the Crimson Fists, and the Black Templars) than, say, the White Scars.

Other than that, it'll be a matter of their own history; if the chapter's home or major battlefield has another chapter nearby, they'll have fought together often enough and will either be close allies or prickly rivals.

3) Chapters don't generally have battleships. Battle Barges are battleship-class vessels but are primarily troop carriers and invasion craft that just happen to be heavily armoured and armed enough to make them dangerous in a naval engagement. Astartes chapters aren't supposed to have 'proper' naval vessels like battleships and line cruisers.

1-3 Battle Barges sounds fine.

6-12 strike cruisers, also fine. You'll often find '10' is a nice number for obvious reasons but in theory it's only ever 'around that'.

50 destroyers? Well, rapid strike vessels often operate in squadrons of 3 or 4. A dozen or so squadrons is a lot, but not unheard of. I'd probably say about thirty or so.

Dropships - Well, every strike cruiser has four or so thunderhawks aboard, and every battle barge six or so. Fifty to a hundred thunderhawks of various patterns (both troop transports and thunderhawk transporters for carrying tanks) doesn't sound unreasonable.

We've never been given a 'fighters strength' for the astartes air wings. 200+ is unlikely, though, because fighters like stormhawks would belong to the armoury; and a chapter generally only has about fifty marines assigned to the armoury, plus maybe half that again in techmarines - so you've only got seventy or so potential pilots if they all deploy in gunships for a mission.

4) Define "a lightning claw in the same style as "the talons of Horus"?" - you want a lightning claw? Easy. You want a lightning claw with a wrist-mounted stormbolter? Possibly do-able (just a stormbolter in one hand and a lightning claw in the other for rules purposes). You want something with the punching power of the actual talon of horus? Definitely not. Daemonic/heretic connotations aside, the Talon was archeotech crafted by the mechanicum at the height of their skill before the heresy - they don't have the ability to remake something like that today.

The chapter master's weapon will almost certainly be unique and impressive - model whatever you like and call it a 'relic blade' - but that's about the limit of craftsmanship available.

5) Some chapters do. Traditionally it's associated with the "**** Subtlety And Tactics" chapters like the flesh tearers.

Chapters don't generally have battleships.

Is it within possible boundaries for a chapter to have atleast 2 or 3?
Or is it straight up to impossible?

Define "a lightning claw in the same style as "the talons of Horus"?" - you want a lightning claw? Easy. You want a lightning claw with a wrist-mounted stormbolter? Possibly do-able (just a stormbolter in one hand and a lightning claw in the other for rules purposes). You want something with the punching power of the actual talon of horus? Definitely not. Daemonic/heretic connotations aside, the Talon was archeotech crafted by the mechanicum at the height of their skill before the heresy - they don't have the ability to remake something like that today.

When i mean "a lightning claw in the same style as the talons of horus" meant more like a chaos raptor lighting claw with a storm bolter attached to it. Not necessarily the same in power but along the same design.

 corfortius74 wrote:

Chapters don't generally have battleships.

Is it within possible boundaries for a chapter to have atleast 2 or 3?
Or is it straight up to impossible?

Define "a lightning claw in the same style as "the talons of Horus"?" - you want a lightning claw? Easy. You want a lightning claw with a wrist-mounted stormbolter? Possibly do-able (just a stormbolter in one hand and a lightning claw in the other for rules purposes). You want something with the punching power of the actual talon of horus? Definitely not. Daemonic/heretic connotations aside, the Talon was archeotech crafted by the mechanicum at the height of their skill before the heresy - they don't have the ability to remake something like that today.

When i mean "a lightning claw in the same style as the talons of horus" meant more like a chaos raptor lighting claw with a storm bolter attached to it. Not necessarily the same in power but along the same design.

Yeah a cool relic weapon will be fine, as long as you just use the rules from a normal lighting claw you will be golden. I should imagine it will look quite cool, and rule of cool usually wins out.

 corfortius74 wrote:

Chapters don't generally have battleships.

Is it within possible boundaries for a chapter to have atleast 2 or 3?
Or is it straight up to impossible?

It's pretty much grounds for having the inquisition sniffing around and other imperial factions to not trust you.

Space marines only have fleets as a means of transport, they are dangerous enough in a fight to win and are heavily armoured to survive orbital defences but they are literally glorified mass conveyors when compared to actual navy battleships. They lost the right to full fleets after the heresy when they were shown not to be trusted with that amount of power again.

 Zaku212 wrote:

 corfortius74 wrote:

Chapters don't generally have battleships.

Is it within possible boundaries for a chapter to have atleast 2 or 3?
Or is it straight up to impossible?

It's pretty much grounds for having the inquisition sniffing around and other imperial factions to not trust you.

Space marines only have fleets as a means of transport, they are dangerous enough in a fight to win and are heavily armoured to survive orbital defences but they are literally glorified mass conveyors when compared to actual navy battleships. They lost the right to full fleets after the heresy when they were shown not to be trusted with that amount of power again.

How would that work with fleet based chapters? Surely they would need to have access to other ship types (as well as bigger guns).

Is it within possible boundaries for a chapter to have atleast 2 or 3?
Or is it straight up to impossible?

Impossible? No. Usual? Also no.

As noted, a chapter's fleet is supposed to be for transport and planetary assault. It's an effective naval combat force because marine equipment is Extra Shiny +1 Awesomeness rather than because it's actually designed for the role, in the same way that the Land Raider is actually a pretty decent main battle tank despite nominally being an APC.

A fleet based chapter generally has multiple battle barges over and above the 'normal' complement, or has a mobile (or semi-mobile) fortress monastery at the heart of the fleet - the Fire Hawk's Raptorus Rex, the Black Templars' Eternal Crusader, the Imperial Fists' Phalanx or The Dark Angels' The Rock.

Adding 'pure' fleet combat assets draws irritation from the Navy and occasionally from the Inquisition, as noted. The Nova-class is a frigate - of a similar size to two other classes of ship the Astartes use in large numbers - but because it's built around a lance, a ship-to-ship weapon, it attracts lots of criticism. It and the Hunter class destroyer (a direct analogue of the Navy Cobra-class destroyer) are most commonly found in the fleets of chapters like the Dark Angels, largely because they don't trust the navy and/or they don't believe the navy trusts them, and they want the capacity to fight naval battles themselves as best they can without essentially declaring war by starting to build capital warships.

There are exceptions. The most common reason is that a second founding chapter (or 'successor' chapter of a second founding chapter rather than one created out of whole cloth by the High Lords) may have a 'venerable battle barge' or other relic warship which is a crusade-era grand cruiser or battleship. The Space Wolves have several (although they shouldn't be taken as "normal" by Space Marine standards - if anything they and the Dark Angels are the poster boys for 'normal marines aren't allowed to do this sort of stuff but **** you because we're special'). They definitely have at least one Emperor-class battleship.

How would that work with fleet based chapters? Surely they would need to have access to other ship types (as well as bigger guns).

Why? Don't make the mistake of assuming a battle barge isn't a warship. It's as fast as any contemporary naval battleship class, more heavily armoured and at least as heavily armed (if at shorter ranges). A chapter fleet build around a squadron of battle barges is perfectly able to defend itself, and if it's attacking an enemy fleet, it would expect to seek navy support just like any other chapter would.

Given that the 'land' the chapter controls for storing ammunition, armour and vehicles, its trophy rooms, chapels, librarium and apothecarion and above all battlefield-scale training halls have to fit on board the ships of its fleet, why would it want to have a battleship-sized vessel that didn't contribute to that?

It just seems that the fleet composition, whilst perfectly balanced for planetary assault and meeting engagements, the overall balance is off for a deep range fleet. Battlebarges are slow and lumbering, strike cruisers are fast and agile and the escorts are ... well escorts much like any other. It just seems that they would require a main line class of ship (ie. cruiser class) when operating alone, and I cant imagine that the Navy would be overly keen to rush off to save a bunch of marines (who are supposed to do the saving!). Furthermore the fleet auxiliary must be massive, needing tankers, miners, armoury ships, mobile fabrication etc. Is there all that much fluff about for fleet based chapter organisation? I cant remember a great deal.
I do remember in the old BFG a pure SM list was a liability mostly as Chaos ships would stay out of range and just pound away with their longer range. (yea I know game doesn't equal fluff but still).

It just seems that the fleet composition, whilst perfectly balanced for planetary assault and meeting engagements, the overall balance is off for a deep range fleet

As noted, they're not supposed to be fighting naval engagements, though.

Battlebarges are slow and lumbering

They are, but not really when compared to Navy battleships.

It just seems that they would require a main line class of ship (ie. cruiser class) when operating alone, and I cant imagine that the Navy would be overly keen to rush off to save a bunch of marines (who are supposed to do the saving!)

Agreed, but that's the point - the chapter isn't supposed to engage a Sector Battlefleet (or equivalent) in a straight fleet engagement. The Marines don't work that way (aside from in a major crusade, where there are enough ships to fight it out); the Chapter goes to where the war is, and if naval battles are going on, they back up the navy.

Defensively they can certainly protect themselves, and can avoid any fight they don't think they can win (the advantage of a mobile fleet-based chapter)

There are deep range fleets - nomad predation fleets, I believe they're called - but the point there is that they don't take on big threats. They attack potential future threats to the Imperium that they can handle. If the Carcharodons come across a heretic empire that's got a navy too powerful for the Nicor and it's attendant strike cruisers to handle, it simply bypasses it and goes to pick on someone more vulnerable.

Furthermore the fleet auxiliary must be massive, needing tankers, miners, armoury ships, mobile fabrication etc. Is there all that much fluff about for fleet based chapter organisation? I cant remember a great deal.

Now that much is true. Fleet based chapters have supply vessels. Generally they have one or more Mechanicus Forge Ships in tow to handle things. There's never been any exacting definition on the supporting logistics for astartes forces but it'll be immense; unlike a guard regiment you need expendable ammunition in vast quantities, along with specialised spares and reactor mass for armour and weapons, and specialist food supplements.

I do remember in the old BFG a pure SM list was a liability mostly as Chaos ships would stay out of range and just pound away with their longer range. (yea I know game doesn't equal fluff but still).

Not all that bad, to be honest - yes, they have longer range, but your higher manoeuvrability, better armour and above all those massed bloody thunderhawks made them a bugger to engage. it wasn't an easy fight, but they could win; it was the strike cruiser and escorts, not the battle barge, that was always the key, though.

Just a quick corrections to what you said earlier Dante is not the oldest. The oldest "living" marine is the guy in the dreadnought from the space wolves, he is over ten thousand years old and fought with Russ. The current oldest space marine is cassias the Chaplin of the ultramarines. He is well over 400 standard years old.

 Backspacehacker wrote:
Just a quick corrections to what you said earlier Dante is not the oldest. The oldest "living" marine is the guy in the dreadnought from the space wolves, he is over ten thousand years old and fought with Russ. The current oldest space marine is cassias the Chaplin of the ultramarines. He is well over 400 standard years old.

Yeah, Dante is older than Cassius http://wh40k.lexicanum.com/wiki/Dante

 General Kroll wrote:

 Backspacehacker wrote:
Just a quick corrections to what you said earlier Dante is not the oldest. The oldest "living" marine is the guy in the dreadnought from the space wolves, he is over ten thousand years old and fought with Russ. The current oldest space marine is cassias the Chaplin of the ultramarines. He is well over 400 standard years old.

Yeah, Dante is older than Cassius http://wh40k.lexicanum.com/wiki/Dante

well Bjorn is older AH HAH! I SAY GOOD DAY SIR!

http://warhammer40k.wikia.com/wiki/Bjorn_the_Fell-Handed

But at the end of the day, the answer is a bloody long time.

 Backspacehacker wrote:

 General Kroll wrote:

 Backspacehacker wrote:
Just a quick corrections to what you said earlier Dante is not the oldest. The oldest "living" marine is the guy in the dreadnought from the space wolves, he is over ten thousand years old and fought with Russ. The current oldest space marine is cassias the Chaplin of the ultramarines. He is well over 400 standard years old.

Yeah, Dante is older than Cassius http://wh40k.lexicanum.com/wiki/Dante

well Bjorn is older AH HAH! I SAY GOOD DAY SIR!

http://warhammer40k.wikia.com/wiki/Bjorn_the_Fell-Handed

But at the end of the day, the answer is a bloody long time.

Indeed he is, bless his ancient heart. I think that's outlined in the article I linked though

 General Kroll wrote:

 Backspacehacker wrote:

 General Kroll wrote:

 Backspacehacker wrote:
Just a quick corrections to what you said earlier Dante is not the oldest. The oldest "living" marine is the guy in the dreadnought from the space wolves, he is over ten thousand years old and fought with Russ. The current oldest space marine is cassias the Chaplin of the ultramarines. He is well over 400 standard years old.

Yeah, Dante is older than Cassius http://wh40k.lexicanum.com/wiki/Dante

well Bjorn is older AH HAH! I SAY GOOD DAY SIR!

http://warhammer40k.wikia.com/wiki/Bjorn_the_Fell-Handed

But at the end of the day, the answer is a bloody long time.

Indeed he is, bless his ancient heart. I think that's outlined in the article I linked though

Bjorn is basically a particularly boisterous fridge at this point, maybe keep this to marines who aren't sitting in a vat with life support up the wazoo?

So a chapter can still have more battleships at the expense being hated by the imperial navy and the inquisition, or the chapter can just have the 1or 2 battleships and they don't have to deal with the inquisition and the navy.
So in total a fleet base chapter would have
1 flagship
3-6 battle barges
4-10 strike cruisers
30 frigates and destroyers
A ton of support vessels ( forge ships etc.)
1 to 2 battleships

 corfortius74 wrote:
So a chapter can still have more battleships at the expense being hated by the imperial navy and the inquisition, or the chapter can just have the 1or 2 battleships and they don't have to deal with the inquisition and the navy.
So in total a fleet base chapter would have
1 flagship
3-6 battle barges
4-10 strike cruisers
30 frigates and destroyers
A ton of support vessels ( forge ships etc.)
1 to 2 battleships

Honestly the takeaway would be that they'd have an imperial navy fleet acting as support but not under the direct command of any of the astartes. but like keep in mind the big names in fleet-based chapters(Blood Ravens, Black Templars etc) only have 4 named battlebarges, which is a huge number of such ships like. (Also Battlebarges usually have their own forges etc as they are supposed to be self sufficient)

 Zaku212 wrote:

 corfortius74 wrote:
So a chapter can still have more battleships at the expense being hated by the imperial navy and the inquisition, or the chapter can just have the 1or 2 battleships and they don't have to deal with the inquisition and the navy.
So in total a fleet base chapter would have
1 flagship
3-6 battle barges
4-10 strike cruisers
30 frigates and destroyers
A ton of support vessels ( forge ships etc.)
1 to 2 battleships

Honestly the takeaway would be that they'd have an imperial navy fleet acting as support but not under the direct command of any of the astartes. but like keep in mind the big names in fleet-based chapters(Blood Ravens, Black Templars etc) only have 4 named battlebarges, which is a huge number of such ships like. (Also Battlebarges usually have their own forges etc as they are supposed to be self sufficient)

How long could such a battle barge survive in deep space, or indeed within the warp, without resupply?

 General Kroll wrote:

 Zaku212 wrote:

 corfortius74 wrote:
So a chapter can still have more battleships at the expense being hated by the imperial navy and the inquisition, or the chapter can just have the 1or 2 battleships and they don't have to deal with the inquisition and the navy.
So in total a fleet base chapter would have
1 flagship
3-6 battle barges
4-10 strike cruisers
30 frigates and destroyers
A ton of support vessels ( forge ships etc.)
1 to 2 battleships

Honestly the takeaway would be that they'd have an imperial navy fleet acting as support but not under the direct command of any of the astartes. but like keep in mind the big names in fleet-based chapters(Blood Ravens, Black Templars etc) only have 4 named battlebarges, which is a huge number of such ships like. (Also Battlebarges usually have their own forges etc as they are supposed to be self sufficient)

How long could such a battle barge survive in deep space, or indeed within the warp, without resupply?

Well given the great crusade was ran from ships like them and they'd only resupply after compliance on a given world, months going on years but that's pure speculation as time frames etc are kinda foggy in GW fluff

 corfortius74 wrote:
#5 can space marines have chainaxes ?

The are, in fact, Chapters that make a wide use of this weapons. Like the Blood Angels or the Carcharodons, in the fluff.

 corfortius74 wrote:
#1 How long can a astartes live for:
I know there are some astartes have lived for quite a while, but how long can a astartes live until he dies?i know the adeptus custodes live more than 10 millennia for protecting the emperor and all, but is it possible to have a chapter master to live that long?

Graham McNeill stated on Twitter a while back SMs were functionally immortal. There's the GK from Pandorax who's from the Heresy, and a Salamander IIRC as well.

 corfortius74 wrote:

#2 what current chapters are the most friendly to new chapters: are there ant chapters that would be most likely to team up with or aid DIY chapters?

They don't really care. Unless your Chapter is from the Cursed Founding (Mortifactors don't like Lamenters), your genetic forefathers had a beef (SWs vs. DAs), or you've pissed off other Chapters (Marines Malevolent <3).

 corfortius74 wrote:


#3 what is the most accurate number of ships in a fleet base chapter? : so far i've heard that its possible to have 1-3 battle barges, 3-5 battle ships, 6-12 strike cruisers, 50+ frigates/destroyers, 200+fighters and a TON of drop ships

Varies; SWs, UMs, DAs, and IFs have way above average, with fleet-based Chapters big as well (but not as large as the First Founding Chapters). However, I've seen those numbers touted before, but I don't know the source. BFG maybe.

 corfortius74 wrote:
#4 can my chapter master have a lightning claw in the same style as "the talons of Horus"? can something like that be commissioned to the mechanicus?


#5 can space marines have chainaxes ?

This:

locarno24 wrote:


4) Define "a lightning claw in the same style as "the talons of Horus"?" - you want a lightning claw? Easy. You want a lightning claw with a wrist-mounted stormbolter? Possibly do-able (just a stormbolter in one hand and a lightning claw in the other for rules purposes). You want something with the punching power of the actual talon of horus? Definitely not. Daemonic/heretic connotations aside, the Talon was archeotech crafted by the mechanicum at the height of their skill before the heresy - they don't have the ability to remake something like that today.

The chapter master's weapon will almost certainly be unique and impressive - model whatever you like and call it a 'relic blade' - but that's about the limit of craftsmanship available.

5) Some chapters do. Traditionally it's associated with the "**** Subtlety And Tactics" chapters like the flesh tearers.

So quick update regarding OPs question about a chapters fleet.

This is what the dark angels have, which is one of if not the largest of the loyalist chapters. Space wolves are the biggest but dark angels are if you could all their successor chapters as still being part of them because of dark angels top foolery.

ANY WAY Dark Angels have the following

The rock: Massive mobile fortress that they launch everything from.

Strike Cruisers x16
Battle Barges x8
Rapid strike Vessels x21
Thunder hawk gunship x31

So the numbers are a lot lower then you think.

Probably best not to go past 3-5 Battle Barges, as they are quite rare. with most Chapters only having 2-3 of them, Some Chapters even having none.

"Most Space Marine Chapters control two
or three battle barges." -Battle Barge listing from BFG Armarda rules.

Even Strike Cruisers are an uncommon thing and most Chapter will have around 10.

"While a Space Marine Chapter only rarely employs the might of its battle
barges, Adeptus Astartes strike cruisers are a more common, although still
rare, sight." -Strike Cruiser listing from BFG Armarda rules.

Obviously a Fleet Based Chapter may very well contain more than the standard number.
Though you could certainly have a Fleet based chapter using only strike cruisers and rapid strike vessels, with a minimum of 10 Strike cruisers, split into groups, could easily deploy to a star system and peel off onto different planets, invading whole systems at once, not every battle in 40k is some Huge war with the deaths of billions. Quite a lot is solved swiftly, and SOMETIMES with out violence... Magical!

"Often the arrival of a Space Marine strike cruiser is enough to
quell a rebellious system. The Space Marines are quick to act if their
enemies’ surrender is not immediately forthcoming." -Strike Cruiser listing from BFG Armarda rules.

Never Under estimate "Right place, Right time" Space Marines are amazing at this kind of Warfare, Being fleet based doesn't mean you have a bigger fleet, just that you're based in a fleet, not from a planet/moon/base etc.

So to sum it up:
#1astartes can basically live for 5000 to 10,000
Years on a good run
#2 mainly chapters of the same ancestry would help each other.
#3 this is my conclusion on my chapter's fleet
1X special flagship
3X battlebarges
10X strike cruisers
20X frigates and destroyers
40ish support vessel's
30X thunderhawks
And 2 battleships
#4 my chapter master can have a lightning claw with a storm bolter on it.
#5 yaay chainaxes


Automatically Appended Next Post:
However a few things still need a bit more clarification
#1 if a chapter master had live and fought for 5 millenia, does he need to go in a dreadnought to be able to fight 5 millenia more. or can he still fight with his own body? (And that's if he had a still functioning body to fight with.
#2 what if my chapter doesn't know it's ancestry, and it doesn't have any brother chapters?
3# can you modify your flagship/fortress monastery
To be more dangerous in ship to ship conflicts (i.e attach a nova cannon on it) i understand that it can still defend itself without any fancy stuff but still i just want my fortress monastery to be more unique.I can always just take it t a forge world to modify it right?


Automatically Appended Next Post:
When i meant need mean required


Automatically Appended Next Post:
(As a side note thanks everyone for helping me.)

 corfortius74 wrote:


Automatically Appended Next Post:
However a few things still need a bit more clarification
#1 if a chapter master had live and fought for 5 millenia, does he need to go in a dreadnought to be able to fight 5 millenia more. or can he still fight with his own body? (And that's if he had a still functioning body to fight with.
#2 what if my chapter doesn't know it's ancestry, and it doesn't have any brother chapters?
3# can you modify your flagship/fortress monastery
To be more dangerous in ship to ship conflicts (i.e attach a nova cannon on it) i understand that it can still defend itself without any fancy stuff but still i just want my fortress monastery to be more unique.I can always just take it t a forge world to modify it right?


Automatically Appended Next Post:
When i meant need mean required


Automatically Appended Next Post:


(As a side note thanks everyone for helping me.)

As mentioned, Dante is the longest-living "normal" Space Marine, and your guy would be five times his age unless interred in a Dreadnought. I only know of a single instance of a Dreadnought Chapter Master (Here). Essentially, being in stasis for large amounts of times and a badly working memory doesn't make a good functioning Chapter Master.

Not knowing its ancestry is not uncommon. No problem doing that.

As far as modifying tech... Easily leads to tech heresy. Remember, even just having a Predator with three lascannons took two centuries to be made acceptable by the Mechanicus.

However, there are examples of it, e. g. the Rock. It is entirely possible, but it doesn't happen very often, and it's definitely not as simple as going to a Forge World. I wouldn't see a big problem with a nova cannon if there is a reason for it, such as the Fortress Monastery often coming under siege by Traitors due being close to the Maelstrom or Eye of Terror. However, adding it to a battle barge would possibly be closer to tech-heresy, as it already has sufficient weapons.

How long could such a battle barge survive in deep space, or indeed within the warp, without resupply?

Based off the Rogue Trader RPG, If it was fully stocked with supplies, an Imperial warship is usually good for a year or so. If it's actively seeing regular combat and expending ammunition, taking damage, etc, probably half that - replenishment underway by transports is still possible, so it need not ever necessarily go dock itself, though, as long as it has auxiliary vessels.

#2 what if my chapter doesn't know it's ancestry, and it doesn't have any brother chapters?

Not all that uncommon.
It will just have to deal with its neighbours and allies from its own history. There are more than enough chapters whose line of descent ends with a broken link of 'origin:unknown' and plenty of them are well known and have both recognised allies and enemies. The Astral Claws (pre-badab war!) are a good example.

can you modify your flagship/fortress monastery

It's more accurate to say that the 'flagship' will be a weird vessel anyway. Anything bigger than a battle barge will be a unique vessel that's not part of a single 'class'. It could easily be armed for ship-to-ship combat, and carrying one or more Nova Cannon is quite possible on something that size.

I doubt they'd have it 'modified' - because the ship itself is a priceless relic both to the chapter and the mechanicus - but it will be a unique ship and was always that way.

#1 if a chapter master had live and fought for 5 millenia, does he need to go in a dreadnought to be able to fight 5 millenia more. or can he still fight with his own body? (And that's if he had a still functioning body to fight with.

As noted, no. Dante is outright stated to be the oldest ruling chapter master. Therefore any chapter master is younger than him.

Based off the Rogue Trader RPG, If it was fully stocked with supplies, an Imperial warship is usually good for a year or so. If it's actively seeing regular combat and expending ammunition, taking damage, etc, probably half that - replenishment underway by transports is still possible, so it need not ever necessarily go dock itself, though, as long as it has auxiliary vessels.

One Year doesn't seem to make sense, considering that Wars can last decades, Not to mention travel through the warp to the destination can take years itself, and I doubt you can send supplies between ships in the warp, smaller ships like thunder hawks and freight transfer ships would not have gellar fields to protect them during travel between ships if that is even possible to begin with. Also consider that these ships are supposedly so vast that whole mini civilisations can exist on the lower decks that no one even knows are there, these people/mutants/whatever they are, probably don't wander over to the mess hall to grab a bite to eat, so there must be some way to produce or obtain food somehow. Out of the warp, there is probably plenty of supply ships somewhere trailing behind to re-arm and re-fuel the line ships.

3# can you modify your flagship/fortress monastery

As others have mentioned, Modifying is pretty big no no, unless you want any Ad mech that see's it to start flipping tables and making loud angry beeping noises refusing to help you because you 110001011'd a "perfect" ship. The best way to go about it, is to explain that it is a Relic Prototype class of ship built long ago and are no longer constructed, originating from a long lost Forgeworld or something like that.

So it's best to find some sort of long lost prototype relic ship and have the ad mech repair it and fit it with weaponry and equipment, such as nova cannons, lances, bombardment cannons or whatever is appropriate.then claiming it as there fortress monestary.However does the chapter get to name it or does the ad mech name it?

So it's best to find some sort of long lost prototype relic ship and have the ad mech repair it and fit it with weaponry and equipment, such as nova cannons, lances, bombardment cannons or whatever is appropriate.then claiming it as there fortress monestary.However does the chapter get to name it or does the ad mech name it?

Very much so. Ifthey found it, it's quite likely they'd be able to keep it - and rather than 'fit it with', it's more a case of 'repair the stuff that was already on it' (which - since you're the narrator, you decide what it was).

According to Battlefleet Gothic, if you find and salvage a hulk the officer commanding the expedition which finds it gets to name it. The Battleship Divine Right was named by the commander who found it's hulk.

One Year doesn't seem to make sense, considering that Wars can last decades,

There is no way in hell even a battle barge can carry enough munitions to supply an astartes company through a decade of high-intensity warfare, though. You have to have transports resupply you from somewhere else.

Not to mention travel through the warp to the destination can take years itself

Yes and no. A really long warp voyage will take several years of real time, but it's highly, highly unusual for it to take more than a year of perceived time. A warp voyage taking 12 months of perceived time would get you from one end of the imperium to the other and would be an expedition you'd supply up for in and of itself!

A 'normal' warp jump is up to about 5,000 light years (old rogue trader rulebook background) - that's a 'jumping across multiple sectors' jump from a chapter's homeworld to a warzone, not manoeuvring around different systems within a warzone (a sector is generally about 200 light years across).

Such a jump will take a maximum of about 3 weeks of perceived time, and about 3 years in real time.

I doubt you can send supplies between ships in the warp, smaller ships like thunder hawks and freight transfer ships would not have gellar fields to protect them during travel between ships if that is even possible to begin with

I'm not talking about replenishment underway whilst in the warp. A battle barge would have to be in real space - but it needn't withdraw from a warzone - it can meet a supply convoy in a system's outer reaches and resupply there, whilst the freighters do the months-or-years job of trekking back and forth to the nearest forge capable of manufacturing ammo.

Also consider that these ships are supposedly so vast that whole mini civilisations can exist on the lower decks that no one even knows are there, these people/mutants/whatever they are, probably don't wander over to the mess hall to grab a bite to eat, so there must be some way to produce or obtain food somehow

No, hullghasts tend to break into and loot supply vaults, or else feed of other vermin, or occasional unwary repair parties. But note that the fact that supply vaults are vast and you can 'skim' off enough to feed hundreds of mutants without it really affecting them doesn't mean that the tens of thousands of crew won't empty them pretty quickly. An imperial capital ship has the population of a small industrial city; imagine trying to stock up sufficient reserves to feed an entire city even for just a year gives you an idea of the vast quantities of supplies a warship carries.

One Year doesn't seem to make sense, considering that Wars can last decades,

There is no way in hell even a battle barge can carry enough munitions to supply an astartes company through a decade of high-intensity warfare, though. You have to have transports resupply you from somewhere else.

Not to mention travel through the warp to the destination can take years itself

Yes and no. A really long warp voyage will take several years of real time, but it's highly, highly unusual for it to take more than a year of perceived time. A warp voyage taking 12 months of perceived time would get you from one end of the imperium to the other and would be an expedition you'd supply up for in and of itself!

A 'normal' warp jump is up to about 5,000 light years (old rogue trader rulebook background) - that's a 'jumping across multiple sectors' jump from a chapter's homeworld to a warzone, not manoeuvring around different systems within a warzone (a sector is generally about 200 light years across).

Such a jump will take a maximum of about 3 weeks of perceived time, and about 3 years in real time.

I can't provide a solid argument beyond personal thinking of the time spent in the warp, as I don't have anything to quote. but surely Bad warp currents could extend your time there, as the warp is rather unreliable means of FTL travel.
And my point about a year of supplies not being enough, is more in relation to food, water and fuel, than expending ammunition. Ammunition would surely be the first thing to go in a long war with consistent naval battles, but wars like that are going to have that fleet of supply ships, I'm more so referring to that one strike cruiser or battle barge that goes off alone to quell a small rebellion in a distant corner with very little activity.

assuming the strike cruiser (Most common vessel for this job due to speed and being somewhat similar to an Imperial Navy Line ship {Dauntless sized}) has one years worth of supply, and take 4 weeks to arrive via the warp due to it being a distant sector, then travelling through the system at sub-light speed (it has been said that transitioning between the warp too close to a star system, the gravity of the star {or other celestial bodies} can cause... Undesirable effects, while not impossible I'm sure, I doubt very much it would be done unless there is no other choice.). Now I have absolutely no idea how fast these ships actually move at Sub-light speeds, they are damn huge, even the smaller vessels, but with massive engines and using gravity wells, we will assume they can go quite fast despite their size. The example planet is in the sweet zone for life like Earth. A quick bit of research shows that a NASA's New horizon probe had an estimated time of 9 years, 5 months and 25 days flying from earth to pluto, Given that we would be flying towards the pull of gravity instead of away, and maybe these huge 40k Ships are powerful enough to move their huge bulk faster than this little probe, we'll shave about 2/3's off the time, that's still over 3 years to travel the distance from pluto to earth. even if we say change this to a smaller system and halve that time, still over 1 1/2 years travel time in system alone just to get there. We can be really generous and halve that again because... it's 40k and things never make sense, the ship would have exhausted about 75% of it's supplies. and now The ships would need to deploy troops from orbit, fight a war that could last weeks, months or years, and then leave the system (which will take longer due to fighting the gravity pull, to transition into the warp out side the gravity pull of the system, and return to resupply. It might sound like a pretty specific set of events, but out of the billions of events, it's bound to happen a fair amount.

Certainly I would think Ammunition would be expended within the year if fighting across a war zone be it be occasional considerable engagements, or consistent brief engagements across the sector, which of course when there is going do be considerable naval engagements, there will be support fleets. My main argument I guess is that these Ships are going to spend a lot of time going places, granted navy line ships are probably going to always have supply ships with them somewhere to keep them stocked up lasting years, but I'm sure Vessels of that magnitude could certainly carry enough food if required to last More than 1 year, something that size should have plenty of room for years worth of food, probably little tiny packets that inflate into a "decent" meal, I imagine like the little bags in the latest Starwars movie. Remembering most of the people on a Navy Warship are practically slaves pulling stuff around. But in relation to OP's queries, Space Marine vessels are crewed by serfs, Servitors and Space Marines, two of those needing very little to no food at all, enabling them to Last much longer then standard Navy vessels. Ground based muntions like bolter rounds, fuel tanks and energy Cells, again, these Ships are bloody HUUUUGE, Considering a Barge Can hold a few Hundred marines, which no doubt many will fall, use smaller amounts of ammunition (due to accurate fire etc.) and it's not like all 300 Marines are going to be holding down the trigger every hour of every day. and I may be wrong, but I am fairly certain that a Battle barge has it's own forge onboard or a fleet based chapter may very well have it's own forge ship. But I think we can conclude that GW is inconsistent and half the time doesn't really make any logical sense and just flat out fails in the maths and physics departments.