Do you think starships are water proof? I would think so given they are space proof, but depth pressure is different from vacuum, yeah? I would also think some starships could stay afloat longer than others. And some are even designed to allow it to float.

If one were to strategically submerge (not scuttle), say, a star destroyer and want to park it on the ocean floor, what do you think its crush depth might be? Once it is parked, could the crew get out using the escape pods?

IMO a starship would have to be either custom-made to be submersible, or else heavily modified to allow it to park on the ocean floor.

Would use up some hard points for sure...at least 1 for Sil3 or less, maybe 2 for a Sil4 ship etc.

Sons of Fortune has a note on this that may help, in the description of Selonia. It mentions "deepwater docks" used by smugglers, and notes that the ships must be "rigged for crushing undersea pressure" and have "underwater propulsion systems attached." This leads me to believe that the average starship is not capable of any significant submersion, hence the modifications needed by the aforementioned smugglers.

In older systems some Mon Cal ships were fluffed as being designed for both space and undersea travel but they were supposed to be fairly rare. I seem to remember a certain light freighter that had shields which could be reconfigured from deflectors to an arrangement to withstand pressures encountered while submerged.

There was an episode in Gene Roddenberry's Andromeda that dealt with this subject... it posed another hazard to spaceships submerging... namely depth charges!

Harpur almost drowned as being the only engineer didn't have time to fix the space suits... so he drowned and Tyr got the water-filled ship clear before resuscitating Harpur.

Might not be relevant in your game but well worth a look and point your players towards if they claim that they're tougher than a sub underwater... note unless your ship was built out of a planetoid or asteroid it certainly isn't and if yes how many of those float?!

Try none!

The ships would be water tight as they are air tight to stay in space. But instead of resisting an outward force from the air inside trying to escape, they'd be fighting an inward force from an incompressible fluid. So, the deeper you go, the more pressure there is on the hull and the more the air wants to shrink in volume. Plus, water would just love to get into those ion exhaust ports and just ruin those pathways by backing up the system making it dangerous to use the main engines underwater. So, you'd need hull modifications to take the pressure (modern, large submarines can't make it to half a mile down before being crushed) and would need a form of propulsion to move through the water.

Like was pointed out earlier though pretty much all Mon Cal and Quarren designed vessels are designed to be submersible regardless of size. Most ships need modding though IMO.

To quote Futurama

Fry: How many atmospheres can the ship withstand?

Professor: Well, it's a space ship, so I'd say anywhere between zero and one.

Keep in mind that all starships are built for the exact opposite role - keeping the pressure at 1 atmosphere inside the vessel, when the pressure outside varies from 0-1 (or more, if intended for non-Earthlike environments) outside.

So, let's say you dropped the bottom of the ship in the water. The bottom's pretty flat, weight would be distributed well, it might float and be okay, only experiencing the weight of the ship above it pushing down and the water pushing back. But as soon as you get it fully submerged, the bottom of the ship is going to be way, way underwater, around 400-500 meters.

At those depths, suddenly the ship is trying to keep 1 atmosphere of pressure inside, and 40-50 atmospheres of pressure outside. Assuming the full height of the Star Destroyer is roughly a third its length, then just when the top of the tower disappears under the water, you're talking about the bottom of the ship being under around 800 psi of pressure.

That's a heck of a lot of pressure for something that is intended to withstand around 15 psi. Things that are intended to be airtight might not be at that depth. And with the ship being so empty on the inside, I'm not sure whether it's even possible to retrofit a ship that big to be pressure resistant.

At the very least, I don't think it would ever be able to take off again. Have you ever tried to pull a frisbee off the bottom of a swimming pool? And that's to say nothing of the mechanical damage of being surrounded by sea water.

As far as the escape pods go, I think they'd still be able to eject, but instead of gracefully flying up and away from the ship, I think they just kind of pop outwards and then stop, like a bullet. If they're built for water landings, they might have some sort of flotation device they could deploy, but that might not be able to withstand 800 psi, either. So my best bet would be that they'd make it about ten meters through the very dark water, deploy an airbag that would implode violently, and then settle slowly to the sea floor. And possible implode as well.

Large flying things are not supposed to be submerged, in short.

Thanks everyone! All good advice and observations. time to come up with a different plan, or perhaps a different sort of ship. At the very least, a heavily modified ship to do the job. I am trying to work in a plot hook into an upcoming adventure where the PCs discover a capital ship or two from the Clone Wars hidden deep beneath the waves. Such a find would be a boon to the Rebellion.

I still like the plot hook, but I'll just have to rework it a bit to not be nonsense.

I *mostly* agree with what's been stated above, but the most recent Star Trek did present a counter-example where the Enterprise is parked underwater to stay hidden.

Basically, I think its best to just apply "plot physics" in cases like this. Park the Star Destroyer in "shallow" water and/or handwave that the world you're doing it on has lower gravity, so the water doesn't apply as much weight to the hull.

As far as propulsion goes, repulsorlifts are pretty much just "magic" and move ships through vacuum and atmosphere (which is really just a fluid) with no reaction mass, exhaust, etc. I'm personally of the opinion that repulsors work underwater, they just have to push the vessel through a *much* more viscous fluid, which slows things down.

Well this is Space Opera and not Hard Science Fiction or even Soft Science Fiction.

If read/watched SciFi where space vessels are able to submerge by default and I have read/watched the opposite.

It is extremely unlikely that FFG will actually give any useful guidance when it comes to ships....

So pick what works best for your plot and group and run with it.

Basically, I think its best to just apply "plot physics" in cases like this. Park the Star Destroyer in "shallow" water and/or handwave that the world you're doing it on has lower gravity, so the water doesn't apply as much weight to the hull.

I would think starships would have to be able to handle pressures > 1 atm, because planet variety is huge, and there might be nebula or solar coronas or some other weird thing they're expected to handle without issue. So if you want to get technical, anywhere from 2 to 5 atm might be reasonable, which would be 10-40m below the surface on an earth-like planet.

http://www.pmel.noaa.gov/eoi/nemo1998/education/pressure.html

I'm with Whafrog on this one.

There are plenty of planets out there with atmospheres of more than 1, so most ships that can go into the atmosphere would be built to withstand at least a few atmospheres of pressure, for landing on planets with denser atmospheres.

Planets that aren't made for planetary landings or even atmospheric flight, wouldn't adhere to this, but then they wouldn't go under water either, since they'd have to do a planetar landing for that.

So, I'd say you could hide a light freighter under water, just a few meters under the surface.
But I'd also say that it wouldn't be good for the ship. Not just the water, but salt and other chemicals wouldn't be good for the ship, and there might be organic material getting stuck where it shouldn't be.
Also, I'm betting thrusters wouldn't work well under water, so you'd have to move using anti-gravitation fields (the stuff that lets speeders and ships hover), which would be slow in the air and even slower under water.

In general, I'd make it possible for my players (or NPC's) but a risky proposition.

Basically, I think its best to just apply "plot physics" in cases like this. Park the Star Destroyer in "shallow" water and/or handwave that the world you're doing it on has lower gravity, so the water doesn't apply as much weight to the hull.

I would think starships would have to be able to handle pressures > 1 atm, because planet variety is huge, and there might be nebula or solar coronas or some other weird thing they're expected to handle without issue. So if you want to get technical, anywhere from 2 to 5 atm might be reasonable, which would be 10-40m below the surface on an earth-like planet.

http://www.pmel.noaa.gov/eoi/nemo1998/education/pressure.html

Just looking in the movies we can see that the ships/technology can withstand a very wide sweep of adverse environments. From cloud cities to underwater cities to buildings that are essentially sitting in lava. While the Cloud City in the movie was at an altitude suitable for humans/Humanoid beings, nothing says there aren't others at much deeper depths being used by other than human races.

For me, my house ruling would be, if you want to park a starship on the floor of the Pacific, as long as you have power to support the atmospheric force fields/structural force fields, you are good to go.

Lose power though and there would be leaks everywhere.....cue dramatic music and let hope those rolls are favorable.

Basically, I think its best to just apply "plot physics" in cases like this. Park the Star Destroyer in "shallow" water and/or handwave that the world you're doing it on has lower gravity, so the water doesn't apply as much weight to the hull.

I would think starships would have to be able to handle pressures > 1 atm, because planet variety is huge, and there might be nebula or solar coronas or some other weird thing they're expected to handle without issue. So if you want to get technical, anywhere from 2 to 5 atm might be reasonable, which would be 10-40m below the surface on an earth-like planet.

I really really don't want to get technical.

That's why I used terms like "plot physics" and "hand-waving." I also put quotes around "shallow" so it's clear it's a nebulous and convenient-for-whatever-you-want definition.

As a GM, you can (and probably should) make your [iNSERT NOUN] do whatever it/he/she/they need(s) to do for plot. So long as it doesn't completely **** suspension of disbelief.

There is no need to get technical. AT ALL.

I really really don't want to get technical.

Understood. When I said "you", I didn't mean YOU you But others might want some arbitrary technical lines drawn, if only to deal with players who demand to know those kinds of limits.

Thanks everyone! All good advice and observations. time to come up with a different plan, or perhaps a different sort of ship. At the very least, a heavily modified ship to do the job. I am trying to work in a plot hook into an upcoming adventure where the PCs discover a capital ship or two from the Clone Wars hidden deep beneath the waves. Such a find would be a boon to the Rebellion.

I still like the plot hook, but I'll just have to rework it a bit to not be nonsense.

Heck man, you're talking about one of the most powerful governments in the galaxy! Steal from Captain America and have there be a huge hangar hidden just beneath the surface. Or a force field, a la Jupiter Ascending, that opens a corridor down to a base carved into the continental shelf. Even a force field, weakening daily, hidden on the ocean floor. Don't have to tweak much at all.

One of the greatest things about Star Wars is the sweeping environments and the technology that's been adapted to work in it. A couple of cruisers would be really useful to the Rebellion, but a hidden underwater base might be even more attractive to them.

I'm pretty sure that Star Wars tech wouldn't have a problem with operating under water as the bongo sub went through the planets "core" of Naboo which I can only assume is deep under water. That being said Lukes X-wing didn't even like being stuck in the mud on Dagobah, so with the appropriate mods I would say a ship could easily dive to almost any depth the plot calls for!

Actually, your plot faces a different problem than the one you think. It's hollow, airtight and light enough to get airbourne. Your ship will probably float.

But on the hypothetical that it does get to the bottom and somehow stays there, yes it would probably go squish. HOWEVER I would have no problem with a Star Wars ship being a LOT more resilient than a real world ship would be. Star Wars tech is rugged as a tractor, on the whole. People slam ships into each other, start machines that have lain dormant for decades or more, patch them up after being hit with weaponized lasers, swap in parts to a Naboo yacht from piles of spares at the back of some toydarian's scrap yard and survive being chewed on by Spacebats. I also once saw a wookie trying to repair a YT-1300 by hitting parts of it with a hydrospanner.

Point is that in Star Wars they build EVERYTHING way, like really, really way, beyond spec. It's like this galaxy has never, ever discovered Upper Management. The engineers are completely unsupervised. It's like how in our society, the driving force of tech is to make everything as small and thin as possible even when we don't need it, except in Star Wars they go for absurd ruggedness as their obsession. R2-D2 is. by the time of RotJ, something like thirty-give years old minimum. He's been handed down generationally! Can you imagine even your vacuum cleaner lasting that long? You're lucky if it lasts three years, never mind three decades. And I bet it's never even been shot!

There's a reason all the tech in Star Wars looks like its from a Seventies vision of the future and it's not because Star Wars is a seventies vision of the future. It's because that stuff is solid. They don't market to iPhone trendy tech-hipsters. In Star Wars, they market to the equivalent of Old West settlers and soviet farmers. No-one wants to be on some remote backwater planet and find their "car" needs a new fuel-injection doohickey and they're trapped forever. In our world we fine-tune everything to be so systems-efficient it'll break if you spill a drink over it. In Star Wars, everything is a Kalashnikov.

Anyway, in my over-excited way what I'm saying is if there's any setting ever in which it's justifiable that a spaceship should have such absurd fault tolerances that it could withstand multiple atmospheres of pressure, it's Star Wars. I have an adventure planned on a sunken ship. It's got flooded parts and air pockets and corroded killer droids and a mysterious killer and everything. It's going to be great. And your adventure should be too!

Point is that in Star Wars they build EVERYTHING way, like really, really way, beyond spec.

And at the same time, as my city planner friend notes there are no guard rails or safety equipment on anything...

Point is that in Star Wars they build EVERYTHING way, like really, really way, beyond spec.

And at the same time, as my city planner friend notes there are no guard rails or safety equipment on anything...

I'm quoting myself from an old thread but my headcannon is that Health and Safety departments and HR departments were created by the Sith, and with the Jedi all but wiping out the Sith, these things never arose in the Star Wars setting. I can practically see the planning meetings now:

"And we're going to put some handrails around the landing platform..."

"Hmmm. Afraid of falling, you are?"

"Well, it's a two-hundred story drop so... yes?"

"Fear leads to anger, anger leads to hatred, hatred leads to suffering. The Dark Side you are encouraging. Conquer your fears instead, you must."

"Could we conquer our fears AND have some hand-rails?"

"No! A false courage this is! Handrails on the landing platform, there shall be not!"

Meanwhile in a parallel Sith-dominated universe:

"No-one is going to use their hair-dryer in the bath or be stupid enough to eat rat poision, do we really need to put all these scary notices everywhere?"

"I find your lack of safety labels disturbing"

But seriously, just look at how people in the Star Wars movies actually behave. I imagine they'd regard our real world society as infantilized to the point of suffocation. Spend some time in Egypt or India and then come back - you'll be amazed how fearful the West seems. Star Wars is a very pioneer society on the whole. Even Corscent reminds me more of Cairo than any Western city. "Don't use that fork, I dropped it on the floor" is something you will hear in no Star Wars cantina ever.

EDIT: This is the mindset of the typical Star Wars mechanic, imo:

What about Bespin? Is Tibanna gas mined by regular ships, or by specially reinforced ships?

When a starship is flying through the air at high speeds how much pressure is the air exerting on its front? Shouldn't it be able to take that much water pressure too?

Do shields protect from pressure damage or is that of a function of the hull (armor in game terms) only?

How high is the atmospheric density in the Tibanna layer anyway? It seems as if Star Wars starships ought to be able to take a fairly high density before they actually collapse, but that they should experience some hull strain and then actual hull damage. The spaceship combat system already models both of these.

What about Bespin? Is Tibanna gas mined by regular ships, or by specially reinforced ships?

When a starship is flying through the air at high speeds how much pressure is the aire execrting on its front? Shouldn't it be able to take that much water pressure too?

A good question. But the ship only has to be able to take that pressure front-on. Think about how a skyscraper has all those vertical struts that enable it to withstand all the vertical compression force but an equal amount of force from the side would have catastrophic effects. But it's a fair point - a ship should take more than just the atmospheres of pressure that it exists within. I don't know if it's ever been canonically stated how deep ships mining on Bespin go. I would imagine the pressure is less than liquid H2O however else it would be effectively liquid they were flying through.

Do shields protect from pressure damage or is that of a funciton of the hull (armor in game terms) only?

I think shields in SW are more about deflecting energy than blocking it. Certainly there are several instances of a ship being damaged even when it still has shields. Vader pulls it off in Rebels, for example.

No idea on the rest, I'm afraid.

In Star Wars, everything is a Kalashnikov.

Anyway, in my over-excited way what I'm saying is if there's any setting ever in which it's justifiable that a spaceship should have such absurd fault tolerances that it could withstand multiple atmospheres of pressure, it's Star Wars. I have an adventure planned on a sunken ship. It's got flooded parts and air pockets and corroded killer droids and a mysterious killer and everything. It's going to be great. And your adventure should be too!

Very well put, Knass. I'm planning on the ships in question being Seppie ships: a Providence class and two or three Recusant class. The interesting thing about both of these is that they are Mon Cal and Quarren designs (Free Dac Volunteers Engineering Corps), which are designed to float on water if need be. So that's a bonus to my plot, but I do feel like despite the ruggedness of the setting you are rightfully suggesting, some modification to ships should be necessary.

Meanwhile, elements of your story's plot sound a lot like mine. Although mine doesn't have a mysterious killer involved. Yet. I'm going to click "I would like to know more."