Operating a starship under water

[CosmicGamer]

I do not think so, because of the significant difference between gas giant atmosphere and sea water, which can both be processed to gain unrefined fuel. In my view the crew uses the fuel processor to extract the hydrogen from the water, and the hydrogen gained in this way is the unrefined fuel, not the water itself.

I don't have other sources available, but in MGT the fuel processors create refined fuel not unrefined fuel and unrefined fuel can be obtained without a fuel processor.

A ship with fuel scoops may gather fuel from bodies of water using hoses. It may also scoop hydrogen from a gas giant...[info on time required and piloting skill checks]...Fuel gathered 'in the wild' is unrefined, but a ship with fuel processors may refine it.

Is this implying that fuel scoops somehow process water into unrefined fuel or does water = unrefined fuel?

 

[rust]

Is this implying that fuel scoops somehow process water into unrefined fuel or does water = unrefined fuel?

I am not sure, but I have no idea what a fusion reactor could use water for.
What it needs for the fusion process is hydrogen, not water, and as I under-
stand it the jump bubble required for the jump drive also is hydrogen, not wa-
ter.

 

[ThunderChilde]

Um, as I recall reading once, somewhere, Hydrogen is refined fuel, and good enough for the jump drive, refiners both filter and process for Hydrogen, but Fusion plants like Duetirium which is processed out the raw Hydrogen. It was one handwavey kind of idea, and I am probably not remembering it clearly.

 

[BlackBat242]

As for SCUBA diving, the safe depth for professional divers is considered to be around 60 meters, everything deeper than that is quickly becoming very dangerous, and therefore professional divers almost always use hard-suits if they have to go deeper.

No. 60m is for compressed air, and commercial divers regularly work at depths up to 100m (330') with soft-suits and mixed-gas for breathing (either self-contained or surface-supplied).

Depth ..... Comments

40 feet/12 meters ..... Recreational diving limit for divers aged under 12 years old and beginner divers.

60 feet/18 meters ..... Recreational diving limit for divers with Open Water certification but without greater training and experience.

100 feet/30 meters ..... Recommended recreational diving limit for divers. Average depth at which nitrogen narcosis symptoms begin to appear in adults.

130 feet/40 meters ..... Absolute recreational diving limit for divers specified by Recreational Scuba Training Council (RSTC).

180 feet/55 meters ..... Technical diving limit for "extended range" dives breathing air to a maximum ppO2 of 1.4 ATA.

218 feet/65 meters ..... Depth at which compressed air results in an unacceptable risk of oxygen toxicity.

330 feet/100 meters ..... Technical diving training limit for divers breathing trimix. Recommended technical diving limit.

660 feet/200 meters ..... Absolute limit for surface light penetration

1,083 feet/330 meters ..... World record for deepest dive on SCUBA



Verified dives below 800 feet
Name - Depth - Year
Nuno Gomes - 1,044 feet - 2005
..... - 890 feet - 2004
..... - 927 feet - 1996
..... - 826 feet - 1994

Pascal Bernabé - 1,083 feet - 2005
..... - 873 feet - 2005

David Shaw - 888 feet - 2004

G.M de Oliveira Brazil - 898 feet - 2002

John Bennett - 1,010 feet - 2001
..... - 833 feet - 2001

Jim Bowden - 925 feet - 1994
..... - 825 feet - 1993

Sheck Exley - 863 feet - 1993
..... - 867 feet - 1989

Don Shirley - 820 feet - 2005

In 2003 Mark Ellyatt is believed to have dived to a depth of 1,032 feet (315 m), but that dive has not been independently verified.

All of the foregoing dives were conducted on open circuit SCUBA equipment, except for David Shaw, who used a closed-circuit rebreather.

Statistics exclude military divers (classified), and commercial divers (although commercial diving to that depth is unknown on SCUBA). In 1989 the US Navy experimental diving unit published a paper entitled EX19 [a type of experimental rebreather] Performance Testing at 850 and 450 FSW which included a section on results from tests on the use of rebreathers at 850 feet. --Knafelc, ME (1989). "EX 19 Performance Testing at 850 and 450 FSW (Feet of Seawater).

http://www.skin-diver.com/departments/crosstalk/commdiving.asp?theID=150

Offshore, inland and coastal commercial divers now work in conventional surface air supplied helmet gear to depths of 180 to 200 feet. Scuba diving is permitted by OSHA regulations to those depths under limited conditions. From 200 to 300 feet, diving rigs using helium and oxygen as a breathing medium are used. To 300 feet, diving is usually performed on a similar mixed gas system, except descents and ascents are done in a bell. The diver(s) exit the bell only long enough to perform what is (usually) a short work time. This type of diving is sometimes referred to as bell-bounce diving.

Full saturation diving has been conducted to depths of nearly 2,000 feet. One classic saturation dive for a crew of eight divers was to 600 feet for 30 days. Several additional days were required for decompression. There is some indication that humans diving to depths greater than 2,000 feet may be subjected to tissue damage, besides the real potential for bends and other physiological problems.

The USN's newest hard-suit has only been certified for 2,000 feet... so it seems people can withstand just as much water pressure without a pressure suit as we can make hard-suits to withstand.

http://www.news.navy.mil/search/display.asp?story_id=25000

The current max depth for a commercial hard-suit is 2300 feet (700m).

 

[rust]

No. 60m is for compressed air, and commercial divers regularly work at depths up to 100m (330') with soft-suits and mixed-gas for breathing (either self-contained or surface-supplied).

More rarely than regularly.

With SCUBA gear beyond 60 meters you can only stay for a short while at
that depth, not enough for any kind of serious work, and you need a lot of
time to get back to the surface. You just can do a lot more work under much
safer conditions in the same time with a hardsuit, and for most commercial
divers time is money, too.
Besides, the risk to get bone necrosis after a couple of years on the job is
considerably lower with hardsuit diving than with SCUBA diving, and many
long-term divers prefer to reduce the risk to have to live in a wheelchair
when getting older.

 

[BlackBat242]

More rarely than regularly.

With SCUBA gear beyond 60 meters you can only stay for a short while at that depth, not enough for any kind of serious work, and you need a lot of time to get back to the surface. You just can do a lot more work under much safer conditions in the same time with a hardsuit, and for most commercial divers time is money, too.
Besides, the risk to get bone necrosis after a couple of years on the job is considerably lower with hardsuit diving than with SCUBA diving, and many long-term divers prefer to reduce the risk to have to live in a wheelchair
when getting older.

That's why mixed-gas (trimix, etc) is normally used... and with surface-supplied gas, your down-time is greatly extended, as decompression is much easier to perform with an unlimited gas supply.

A lot of salvage divers are using this technique, especially in the oil industry... an example being the clean-up after hurricanes in the Gulf of Mexico.

 

[ThunderChilde]

Getting back to the OT, a ship that can:
A. dive deep enough to skim a gas giant
B. land on Venusian worlds and survive
c. survive all kinds of insidious and high pressure atomospheres
d. land and deliver cargo and passengers in all conditions up to and including sea worlds and perhaps deep water colonies.
e. canonicly sit on sea bottoms deep enough to be masked from orbital survailance (SDB's, some warships)
and all it takes is streamlining to do this. I hesitate once again to beat the drum of its 5,000 years in the future, they have had a long time, with a lot of brilliant people to work out this capability.

Handwave away if you wish, I just am not willing to naysay the possible unforseen advances that make all this common and safe.

 

[flykiller]

... and all it takes is streamlining to do this.

yeah. but "Can this really be true?" no. physics and all that.

'course, if one wishes to keep the handwave it but provide it a fig leaf, one may simply double the cost and construction time of any streamlined ship.

or break it up into component features. simple streamlining, flight controls, water landing, ocean refueling, gas giant skimming, galvanic corrosion resistance, corrosive atmo resistance, insidious atmo resistance, deep diving, underwater sensors, multi-environment airlocks, all available individually or in any combination - for a price.

exterior weapons priced separately.

 

[the angle]

Once you have the ability to control, manipulate, and even generate your own gravity, nearly anything becomes possible. I could see starships diving to the bottom of the ocean without the hull ever actually getting wet. The better question here (IMO) is not whether it's possible but whether it's right for YTU. There's a lot to be gained by allowing it, and just as much to be gained by requiring special craft for underwater travel. The answer lies in what's best for the story you're trying to tell.

Steve

 

[Patron Zero]

Jump Hulls

Mind I tend to treat starships IMTU a bit like WWII-era submarines but that's more done for 'flavor' than technical or engineering purposes of canon-accepted rules.

Any vessel over 100 tons must have what is referred to as a 'jump hull', essentially this is an outer shell that mimics-mirrors the starship's basic shape and is a second skin over the interior hull. Mind there is a small space between hulls that house avionics, sensors and other equipment that have need of access to the ship's exterior surfaces.

Jump hulls are not armor in the true sense but do provide the needed protection from the dangers of traveling in jump space, such being jump fire, unknown radiations and other as yet documented phenomena.

That said, a starship with a jump hull could survive significantly much more direct pressure from the depths of an ocean or a gas giant's thickening atmosphere.

Again, far from canon but a taste of my 'house rules' that dress the stars and the starfarers in my game.

 

[Brian Blank]

IMTU, All streamlined ships and boats have some underwater capability, but it's limited to frontier refueling or hiding.

Civilian ships will usually dock with a Highport and transfer their cargos to dedicated Aquatic Spacecraft ( modified Scout, Far Trader or SDB hulls) for transfer to Undersea Habitats, or land at the planets downport ( either natural or artifical island )

Certain Military Craft are equipped to operate in Undersea enviroments as a matter of course. Mostly SDB's but the Type-T Patrol Cruiser can also operate at depths of up to 1500ft. The Scout Service Type S is also at home in the ocean if needed though they prefer using the Type Sa ( Scout Aquatic) which is specifically designed for Ocean exploration.

A few SDB hulls have been heavly modified as Deep Diving research craft and can handle the deepest ocean trench areas .

I think Gurps Traveller had a Safari Ship variant that was designed to operate underwater.

 

[Hemdian]

Not sure how this fits in but CT Adventure 12 (p18) states ...

Commercial vessels (traders, merchants, liners) can withstand up to 1,000° K and up to 1,000 atmospheres. Military vessels can handle temperatures to 1,500° K and pressures to 2,000 atmospheres. System defense boats are specifically constructed to handle temperatures to 2,500° K and pressures to 3,000 atmospheres.

Regardless of whether or not the figures are bogus, it's interesting that commercial, military, and SDBs are rated differently.

 

[far-trader]

Regardless of whether or not the figures are bogus, it's interesting that commercial, military, and SDBs are rated differently.

Partly a factor of armour I'd guess, but also a degree of the other aspects required.

Interesting figures though. Using the rule of thumb of 10 m per atmosphere of pressure (standard Earth pressures and sea water) that makes:

Civilian ships capable of operating at 10,000m depth.

For comparison modern subs have an operating depth of about 500m and a crush depth of about 750m.

The Adventure 12 numbers sound a little extreme to me. Even specialized deep submersibles are only routinely operating at about half that depth (4000m) though they could possibly go deeper. I seem to recall the record is about 10,000m which is also about the deepest ocean depth on Earth.

Personally the depths noted in the adventure sound patently ridiculous. And to a degree useless. If the deepest part of an ocean trench on a large world (Earth) is the operational depth of a civilian ship what's the point of having deeper depths available? Where's the adventure and danger in worrying about crush depth?

Even a tenth that would be fantastic but at least believable and more likely to make a difference between the types of ships and provide at least a little room to worry about crush depth.

 

[Trent]

There was a published adventure (LBB format) called, I believe it was spelled "The Drenslaar quest" that had a small trading vessle smuggling arms being shot down and sunk in an ocean on a class M planet and the PCs were hired to find her and salvage the cargo, which included battledress.

The article dalth with underwater ops, and as an interesting bit in it the drenslaar looked very much like a klingon vessel.

 

[Icosahedron]

I agree with FT, canon or not, those depths are simply unbelievable - especially for craft designed primarily to withstand just one atmosphere of negative pressure.

I dunno about dividing them by 10, I'd want to divide them by at least 100.

Or maybe armour^2 atmospheres wouldn't be a bad rule of thumb - with a caveat that all craft are rated for periscope depth.

The only place you could get crushed in those canon craft is a gas giant atmosphere.

 

[Hyphen]

Dear Folks -

Not sure how this fits in but CT Adventure 12 (p18) states ...


Regardless of whether or not the figures are bogus, it's interesting that commercial, military, and SDBs are rated differently.

Had forgotten that one; I was going to quote the variant rules from "Seastrike" by Marcus L. Rowland, JTAS #22. It was included as a parallel article to Marcus' "Thing in the Depths" Amber Zone scenario in the same issue.

It included a discussion on the effects of water (or other liquid) on weapon use, a set of underwater detection gear, and even rules for water as armor. Note that similar equipment is included in the MT ship design rules.

For the latter, in nugget format, see Clayton Bush's treatment on my website (link in .sig). Go to:
==>"Best of the TML"
==> Amber Zone
==> Amber Zone - All JTAS Amber Zones in nugget format (JTAS 1 to 24)
==> The Thing in the Depths

FWIW, I assumed all my streamlined-or-better MT military ships (and even paramilitary, like scouts) were underwater-capable, and outfitted them with underwater sensors as a matter of course.

OTOH (and a tip'o th' hat to flykiller), there's nothing to prevent you, the referee, from handing the PC's the unpleasant surprise! At an inconvenient time, they might find out that their ship's standard anti-corrosion surficant was not properly re-applied during their last annual maintenance, and the bare areas unfortunately allow corrosion and thus fluid inside the vessel... kinda like "Wrong Way Valve" (scenario from an early Challenge).

 

[Hemdian]

OTOH (and a tip'o th' hat to flykiller), there's nothing to prevent you, the referee, from handing the PC's the unpleasant surprise!

And talking of unpleasant surprises let's not forget the "Dispair Squid" (or some Traveller-ised variation). :devil:

 

[Nick Bradbeer]

If you're running a space-opera style game, then I guess the answer is "they can if you want them to." Ships designed for hypersonic fuel skimming, SDBs milled out of a single block of crystalliron - who's to say what's a ridiculous depth for them to submerge to?

If you're running a more technically gritty style game, then you're right - there are a whole bunch of issues. There's still a lot of technical assumptions to be made, and even Fire Fusion & Steel doesn't design ships in enough detail to let you actually calculate a maximum depth. But if you are interested in detail, I'm a submarine designer and I can give you some equations for things like structural collapse pressures. Assumptions will be required.

 

[Hemdian]

But if you are interested in detail, I'm a submarine designer and I can give you some equations for things like structural collapse pressures. Assumptions will be required.

I'd be interested in seeing a bit more than that, please. (Though I'm more interested in the implications for gas giant refueling.)

As for assumptions there was something about buckling decks on AHL cruisers doing GG refueling. But, again, it was from an early source so it may not stand up to close scrutiny.

 

[Nick Bradbeer]

I'd be interested in seeing a bit more than that, please. (Though I'm more interested in the implications for gas giant refueling.)

As for assumptions there was something about buckling decks on AHL cruisers doing GG refueling. But, again, it was from an early source so it may not stand up to close scrutiny.

Hey dude!

The same principles apply to deep gas giant operations, but fuel skimming operations are probably happening at sufficient speed (hypersonic) that dynamic pressure considerations and heating outweigh the static pressure considerations. That said, SDBs on deep lurking stations inside gas giants would suffer the static pressure loads.

What do you want to know?