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Does anyone know any examples of marines fighting underwater / in space or any other environmental situations. I'm curious on an underwater focus. Mostly if possible, time allowed, hindrances etc. Could throw in weaponry into this as well bolters, plasma etc underwater. I've looked on Lex but the closest it comes to explaining anything dealing with environmentals is this clip from the 'Components' Section...

http://wh40k.lexicanum.com/wiki/Power_Armour

Respirator Vox Grill: This thought-activated device amplifies a Marine's battlecry to deafening volumes and contains a respirator to filter out toxins and draw upon an internal oxygen supply.

I have a 'sea marine' idea and wondering if its too outrageous or not from a fluff perspective, limitations of the idea what not.

not otu ragous at all, one codex (wanna say space wolves) details a marine strike force of land raiders and other vehicles crawling along the bottem of an ocean to crush a underwater Tau base

In the farsight damocles gulf campgaign book they were fighting in space for a bit.

I wouldn't know how that would work, considering the exhaust vents on the backpack. Those fill with water, it's going to smother the power plant.

Space Wolves do it a bit.
Read Lone Wolves and Lukas the Trickster. Neither one is a long battle because they're Space Wolves and naturally left their helmets at home but Lukas the Trickster in particular gives detail on how Power Armour sorta-kinda works underwater but isn't designed for it.
Your Marine Marines wouldn't be the first to modify armour a tad for environmental warfare.

Know No Fear has an example of fighing in space:



I would imagine the internal O2 supply is more to assist in atmospheres that are particularly thin, or otherwise polluted/contaminated, rather than the hard vacuum of space.

I was always under the impression that Marine power armour could function as a completely sealed hostile-environment suit for a limited time; maybe the powerplant doesn't need the vents running continuously?

As for weapons lasweapons would be problematic, but my understanding of the problems of underwater guns suggests you could put together a skinnier bolt round optimized for water rather than air and then fire it out the same boltgun barrel by way of a sabot, so you could try using Deathwatch-esque multiple ammo feeds on their boltguns.

Given the issues of energy weapons dissipating more into the medium I'd expect your underwater-Marines to have developed an arsenal built around grenade launchers and guns firing explosive projectiles; a short-ranged meltabomb-launcher rather than a meltagun, for instance.

Underwater melee weapons would need to be shorter (to swing through more resistance) and/or stabbing-focused; fewer chainswords and thunderhammers, more knives, short power swords, and spears.

 AnomanderRake wrote:
I was always under the impression that Marine power armour could function as a completely sealed hostile-environment suit for a limited time; maybe the powerplant doesn't need the vents running continuously?

In water you could probably cool the powerplant a lot easier - it does after all transfer heat a lot better. Space or really thin atmospheres would put a lot more strain on it since heat isn't getting dumped efficiently. Maybe the backpack has a coolant tank from which the suit periodically feeds in some to be vaporized and vented as hot steam?

As I recall way back in the RT days SM back packs had limited thruster capabilities. Marine armour has really flexed back and forth on its built in systems over the years. Sometimes it's nothing more than sealed plate armour. Other times it's super strength lending, with a super Heads Up Display yielding tons of data. This is welded together with the caveat that all PA is hand built one at a time by limited number of master armor smiths. So in the long history of wildly erratic background I say go with the rule of cool.

If the power supply is a fusion magic thing (which i always thought it was) you don't need air. But you propably need cooling. Because all reactors we know produce only heat. And the heat needs to be converted to usable energy - mechanic or electric. To do this you need some form of heat transfer system, and also need to provide a way to get rid of excess heat. The vents are more likely heat exchangers (by moving any fluid - gas or liquid through it).
And for that you can take any fluid medium... poison air, breathable air, liquid. Just vacuum would be not ideal, because it is... well... nothing and therefore doesnt work to exchange via convection.

Hrm. Heat dissipation could be a function of some hyper-efficient internal radiator running through the backpack.

The design of the rebreather includes 3 terraces at the bottom - which would be a good place for some internal cooling unit. I actually thought that was the original intent, since the 4 vents appear on the sides.

I was surprised to find out that power armour had inertial dampeners.

Whatever you do, don't use a plasma gun underwater.

 Mr Nobody wrote:
Whatever you do, don't use a plasma gun underwater.

Why ?

 godardc wrote:

 Mr Nobody wrote:
Whatever you do, don't use a plasma gun underwater.

Why ?

Because it could potentially flash boil you face off, if it works at all.

 Flinty wrote:

 godardc wrote:

 Mr Nobody wrote:
Whatever you do, don't use a plasma gun underwater.

Why ?

Because it could potentially flash boil you face off, if it works at all.

So it functions as normal?

A bit more likely than normal given that if it does fire anything the power of the sun gets instantly dumped into the water.

The pressure wave of the flash boiled water could potential crack open power armor.

Wow, interesting ! What about a lazcannon ?

There are numerous mentions of marines operating in different environs, like hard vacuum or poisonous sludge, without too much of a hassle. Add in some flavour of Chuck Norris geneseed and you have people like pre-fall Death Guard who revel in their ability to waddle through acidic waste or corrosive atmosphere that eats away lesser hazmat suits. Of course you have to replace outright broken parts from the suits, but power armour is designed to handle pretty rough times.

I believe they more often than not don't participate in underwater operations because those aren't of the kind marines excel at. On land the astartes is faster, stronger and more brutal murder machine than ordinary men that is thrown in the oppositions face when they must be broken right then and there whereas underwater ops are usually special ops that aim to extract spies, plant bombs to ships and dams or otherwise sabotage enemy materiel. A normal man can do that just fine, especially if given a properly scifi hydrosuit with propulsion systems. But of course this isn't to say there wouldn't be times when the astartes just have to go under the surface...

Edit: regarding energy/laser/plasma weaponry: yeah, just don't. Pressure waves and detonations underwater do horrendous damage to anything near and above them. You want special ammunition there, which marines oddly enough can handle pretty easily if you just fiddle a bit with the bolt casings. Jut switch from miniature rockets to miniature torpedoes and you'll do just fine.

I think PA is powered by a tiny nuclear/fusion reactor. The bulbs and vents on the backpack could just be air intakes for breathing or for directional circulation through the backpack to assist in atmos[heric heat exchange.

I would think in vacuum you could turn down the power requirements of the power armor if the marines are not on a gravity source, If they're in hard vacuum the thousands of lbs they move are weightless and would primarily just need minimal life support and communications.

Underwater I would imagine the power armor needs to be cranked up to overcome the resistance of a fluid environment. But , seeing as the environment now acts as a heat exchanger with relatively infinite capacity, its okay to crank the PA to max. and most likely move about closer to normal "human" speed. Bolters on the other hand have a sold fuel propellant in the back of the bolt and a 2 stage firing. I think if the solid fuel is water resistant or non-degrative with water it should still work fine. I agree though that a smaller caliber, longer bolt would be required if any kind of range is wanted. Lasers are pretty much useless, LIDAR has problems with cloud cover because of the water/optical density. You'd probably just boil the immediate vicinity with a Lascannon and a plasma gun is bad news bears.... krak grenades on the other hand potentially become FAR more effective with a pressure change

Given the name ‘marine’ derives from ‘marine corps’ or soldiers attached to a navy, it would be a nice return to the origin to have that mean underwater Astartes. Go modelling crazy!

Seal up the backpack vents, add a pointlessly-upsized grimdark respirator, downsize vision slots or use Inceptor shields. So much potential!

As was stated by someone else, I am assuming the armor is powered by a source that is convection cooled. That is, air gets sucked in, then the same air gets pushed out carrying the excess heat from the power source. Assuming robust enough components, I don't see why this wouldn't work in any kind of fluid medium, including water. Water would be sucked in, then hot water would be pushed out of the vents carrying the excess heat just like air would.

In space though, this would be impossible since there is no medium for convection cooling. The suit is probably able to tell if it is operating in vacuum and adjust accordingly by utilizing some other type of exhaust system.

 godardc wrote:
Wow, interesting ! What about a lazcannon ?

Maybe. Lasers are weird. Diffusion would depend upon the wavelength of light and the solution of the water. We have lasers that remove tattoos by heating the ink particle but do not effect the skin layers above, so it's not unheard of. Lascannons would have a much shorter range, but with some fine tuning you could make a submersible laser weapon.

Their armor is definitly Void proof, but the basic space marine armor was never designed for sustained void combat. They can probably survive in the void for a few hours.

Now suit like terminator armor is much for suited for void combat, as it can and does sustain the marine for a very long time in the void.

Source for TDA being that good in void fighting?

pm713 wrote:
Source for TDA being that good in void fighting?

Every space hulk novel ever id imagine, a lot of those are open to the void, even further into hulks you still get ships open to the void, also given that dreads are hermetically sealed, it makes sense that tactical dreadnought armour is the same, in addition it would have the full suit of systems that sustain a marine in standard power armour, so proving the seals are not damaged a marine could and would enter a susain coma and possibly last weeks in the void.. all depending on how long the power holds out.

Best example I can remember was the soul drinkers Series, pretty sure it has a marine that was vented into space and lasted a fair while.

Seem to recall the John French short story 'The Crimson Fist' starting with a marine stranded in the void after a space battle?

I need to re-read it, it's one of the best pieces of 30K writing ever.

I remember the armour used to have some electromagnets in the shoes and that the upper bulblike vents are more for stabilising the marine than actual venting so PA can work in the void though it's limited.

 Viridian wrote:
Does anyone know any examples of marines fighting underwater / in space or any other environmental situations. I'm curious on an underwater focus. Mostly if possible, time allowed, hindrances etc. Could throw in weaponry into this as well bolters, plasma etc underwater. I've looked on Lex but the closest it comes to explaining anything dealing with environmentals is this clip from the 'Components' Section...

http://wh40k.lexicanum.com/wiki/Power_Armour

Respirator Vox Grill: This thought-activated device amplifies a Marine's battlecry to deafening volumes and contains a respirator to filter out toxins and draw upon an internal oxygen supply.

I have a 'sea marine' idea and wondering if its too outrageous or not from a fluff perspective, limitations of the idea what not.

A bunch of examples come to mind.

Crusaders of Dorn has Terminators teleporting into an atmosphere of "super pressurised boiling liquid hydrogen". They end up having a fight with Mandrakes (who apparently are quite happy wandering around this environment) over who gets to murder some Cythor. Stormbolters and power weapons still function. Interestingly there is another example of Terminator armour having a bunch of mini-grapnels built in, as they initially brace themselves with these when they arrive, and the teleport shockwave ripples back at them due to the slightly different pressure of the displaced volume. (they teleport from pods of highly pressurised fluid to avoid the worst of this)

Black Tide, by James Swallow has Blood Angels fighting on the hull of a submersible against aquatic Tyranids.

Weaponry is generally functional, including bolters, plasma guns and power weapons, although its stated that their effectiveness is decreased, range and power attenuated etc. The sub itself has lasers with wavelength adjustments for use underwater. They use maglocks on their feet, and tethers.

Some examples.

“Advance!” called the sergeant, his power sword’s active blade wreathed in a halo of frothing bubbles. “Move in and engage all targets of opportunity!....

He checked the ammunition loads in the sickle magazine; the mass-reactive rounds were less a bullet, more a miniature rocket, and each one contained within its casing a measure of oxygenated igniter compound. Thus, even in stark vacuum or, as now, in a fluid environment, the boltgun could still deliver its lethal load.
He worked quickly, adjusting the iron sights and the muzzle brake; the waters would attenuate the velocity and range of the weapon by a large degree....

Then for the first time, the sergeant raised his plasma gun and fired it; for a brief moment the area around the warriors was illuminated with a stark, hard glow that threw jumping shadows. A streak of burning white plasmatic matter lanced through the water, boiling a channel towards its target, and for a split-second Rafen vanished in a shroud of churning froth as the gun’s heat-displacement backwashed across him...

BrianDavion wrote:
not otu ragous at all, one codex (wanna say space wolves) details a marine strike force of land raiders and other vehicles crawling along the bottem of an ocean to crush a underwater Tau base

It was Space Wolves, the tau had a bunch of deep sea adapted stuff as well, and Thunderhawks apparently can drop underwater munitions amongst other things.

 AnomanderRake wrote:
I was always under the impression that Marine power armour could function as a completely sealed hostile-environment suit for a limited time; maybe the powerplant doesn't need the vents running continuously?

As for weapons lasweapons would be problematic, but my understanding of the problems of underwater guns suggests you could put together a skinnier bolt round optimized for water rather than air and then fire it out the same boltgun barrel by way of a sabot, so you could try using Deathwatch-esque multiple ammo feeds on their boltguns.

Given the issues of energy weapons dissipating more into the medium I'd expect your underwater-Marines to have developed an arsenal built around grenade launchers and guns firing explosive projectiles; a short-ranged meltabomb-launcher rather than a meltagun, for instance.

Underwater melee weapons would need to be shorter (to swing through more resistance) and/or stabbing-focused; fewer chainswords and thunderhammers, more knives, short power swords, and spears.

In Black Tide there are magnetised "hull-cutter" krak grenades, they toss them into currents to hit some nids. Presumably they could make infantry usable versions of the underwater optimised lascannons it mentions as well.

 Keep wrote:
If the power supply is a fusion magic thing (which i always thought it was) you don't need air. But you propably need cooling. Because all reactors we know produce only heat. And the heat needs to be converted to usable energy - mechanic or electric. To do this you need some form of heat transfer system, and also need to provide a way to get rid of excess heat. The vents are more likely heat exchangers (by moving any fluid - gas or liquid through it).
And for that you can take any fluid medium... poison air, breathable air, liquid. Just vacuum would be not ideal, because it is... well... nothing and therefore doesnt work to exchange via convection.

The Badab War book describes that there is a basic proofing against adverse atmospheric conditions, and that power armour will function more or less normally in deep space. It refers to the practise of "void hardening" when Marines are expected to fight in extremely hazardous space conditions ( solar corona shadows, micrometeor storms and high radiation zones are mentioned). Alternations potentially include, extended air supplies, enhanced coolant systems, ablative armour, additional attitudinal correction systems. The example shown is a Salamander marine, who has a fancy heat dispersal system in the form of cool dragon/serpent designs that double as radiators all over his armour, which glows when operating at high capacity. Presumably at that point he's not bothered about any visibility issues.