Operating a starship under water

[Thunderbolt]

The 'Underwater Environment' states:

"Starships, ship's boats, and other space-going craft are virtually
unlimited in their ability to deal wlth pressure effects, and so can
function normally."

Can this really be true?

A cursory glance over the designs of the CT ships shows shapes and fittings that would appear to fare very badly under a high inward pressure, windows, cockpits, and flattened or completely flat surfaces with no use of curves to distribute the pressure.

If submarines and particularly deep sea submersibles are anything to go by, a starship capable of moving at depth underwater would be a peculiar beast, with specific modifications and bracing to counteract the intense pressure; seals on doors, special windows, protection against corrosion and so forth.

A pressure door designed to keep in one atmosphere of pressure from the inside, is surely different from one that keeps many atmospheres of pressure pushing in from the outside, and the hull bracing and design would surely follow suit to stop the hull imploding.

I'm only asking because my new ship design followed submarines in approach, and I gave it waterjets and manoeuvring fins, and figured it would have to sacrifice space in the form of armour to simulate its internal bracing !!!

 

[robject]

From my point of view, it depends on the Traveller ruleset.

CT starships tend to have a lot of nice assumptions loaded into them: they're able to skim gas giants at high speed, make water landings, have VTOL capability, land with wings and wheels (some of them), and lurk in the depths of the ocean. All of this, due to the "Streamlined" option... and some of them appear to have wings or lift bodies, I think.

Presumably, high tech materials and design science makes these features accessible.

Other rulesets may vary; I'm not sure about any of them nowadays except for T5, which requires designers to designate floatation hulls and submergence hulls. There is a cost, volume and price-wise, but it is modest.

 

[flykiller]

The 'Underwater Environment' states:

"Starships, ship's boats, and other space-going craft are virtually
unlimited in their ability to deal wlth pressure effects, and so can
function normally."

Can this really be true?

nope, no how, no way.

and as for "function normally", ocean ops present many difficulties besides pressure. galvanic corrosion will ruin sensors, weapons, and fittings not specially (and expensively) designed to deal with it. vast hordes of sea life will attach themselves to the hull. sensors designed to operate in a vacuum will be useless underwater (and vice versa). airlocks designed to cycle between vacuum and air will not be able to cycle between air and water. etc.

underwater ops will require vessels designed for it.

 

[Icosahedron]

IMCTU, all spacecraft have some underwater capability. Yes they need to be designed for this - but they are.

It is anticipated that sometimes ships will need to enter atmospheres, to skim and dip for fuel, and perhaps to enter sea-bed structures. To this end, they are manufactured as standard with a degree of oceanic capability.

However, they are not designed for long-term or deep-diving aquatic use. I'd say perhaps 3-5 atmospheres before you need a new design. And yes, I know even that's a handwave - in reality you'd be hard pressed to get a starship to float, much less submerge, but CT says it's possible.

Of course, 3-5 atmospheres won't get you very deep, but in general it will let you dip for fuel without crushing your ventral turret or springing a leak around your landing gear.

In real life, some of the deepest diving nuke platforms can barely reach depths equal to their own length - forget Voyage to the Bottom of the Sea. The bigger it is, the shallower it can dive.

 

[Spinward Scout]

vast hordes of sea life will attach themselves to the hull.

Yeah, but isn't that the "fun" part?



I would think that a multipurpose vessel like a starship that's designed to go in and out of pressurized environments (like atmosphere) would be just fine underwater. Now moving through that environment might be something different than you'd expect...

 

[Thunderbolt]

According to Wikipedia (so it must be true!), a Los Angeles class submarine can go down to 200 metres, which equates to 20 atmospheres of inward pressure, not a typical situation for a spacecraft hull to be dealing with !

 

[morfydd]

and an LA class fast attack is 110 meters long ..but in reality it can go beyond the 200 meters ..Same with the Ohio (170 M listed as 240 meters for test depth)

Yep those are the "Official maximums" as given to Janes Ship's and Planes ...now we all know the military will not give an accurate listing of speed and depths of subs to a publication anyone can purchace

Now for a deep diver Go look at NR-1 http://web.archive.org/web/20030429014652/www.chinfo.navy.mil/navpalib/factfile/ships/ship-nr1.html

724 meters and yep it is much smaller (to bad after 40 years shes been decommisioned but then again she did serve for 40 years under the harshest environments)

 

[Karma]

I think there is no problem going underwater with any sort of "reality check" as long as you limit the depth to around 20 meters. My reasoning being the interior of the ship is already pressurized at 1 atmosphere so if you go down 20 meters you have 2 atmospheres pushing in and 1 atmosphere pushing out for a net of 1 atmosphere on the hull. The net effect would not stress the hull any worse than it does in space between 0 atmospheres in a vacuum against 1 inside the ship.

The ship is already airtight and while a watertight seal is harder to maintain, especially pressurized water, I'd give them a pass on this since it is a known design quantity. I wouldn't let the airlocks function underwater unless they are specifically designed to handle fluid pumping though. Also exterior iris valves would be right out since they can't close and maintain any sort of pressure seal.

As others said, you could have all sorts of issue with marine life, salt and other minerals attacking the hull or seals, and so on. As for sitting on the "bottom" of the ocean, as is mentioned in some canon sources, I don't think so unless it was something like a Broadsword that was mainly spherical.

There is a good reason submarines and steam locomotives have that cylindrical shape, when dealing with high pressure the wall thickness gets out of hand quickly if your not using the optimum shape.

 

[Spinward Scout]

Only 200 meters for a submarine? You're kidding right? The deepest scuba dive is 318 meters.

http://www.scubarecords.com

 

[aramis]

Given that the rating of the hull is for 50ATM failure, the LA Class should be able to go to some 300m safely. "Officially" they only go 200m deep... but that's propaganda.

 

[flykiller]

vast hordes of sea life will attach themselves to the hull.

Yeah, but isn't that the "fun" part?

can be. 'specially when an intelligent electric "whale" decides it likes your ship and tries to "communicate" with it.

yeah, a ship should be able to settle into water, or even submerge a bit, without excessive pressure problems. galvanic corrosion and sea life will still be issues though.

at 1g, 33 feet of water = 1 atmosphere i.e. 14.3 psi. as ref I'd rule that anything below 33 feet requires submersible ops design and, by the by, a crew trained to use that design. "hey, who forgot to reverse-dog the engineering hatch!!!"

 

[BlackBat242]

I question the vulnerability of a starship hull to ordinary sea-water... even considering galvanic corrosion.

After all, aren't standard starships rated for insidious gasses like hydrogen (gas giant atmosphere) and corrosive atmospheres?



Does anyone have a CT reference that says special starships are required for landing on a planet with a corrosive or insidious atmosphere?

I don't remember any such.

 

[aramis]

I question the vulnerability of a starship hull to ordinary sea-water... even considering galvanic corrosion.

After all, aren't standard starships rated for insidious gasses like hydrogen (gas giant atmosphere) and corrosive atmospheres?



Does anyone have a CT reference that says special starships are required for landing on a planet with a corrosive or insidious atmosphere?

I don't remember any such.

Shadow shows the opposite... normal ships can land on corrosive worlds just fine... so long as they don't crash.

 

[Icosahedron]

I was about to mention that very point about corrosive atmospheres, BlackBat. Also, IMTU I can electrify the hull - not whilst underwater, perhaps, but I can certainly remove sea-life from the hull without too much trouble afterward.

A human diver is very small, largely comprised of incompressible fluid, and remarkably tough, I'm not surprised that he could out-dive some submarines - he won't surface as fast, though...

Some sea beds are less than 100m down, so you might sit on them with the right ship. The North Sea and the Caribbean are fairly shallow, for example.

 

[rust]

There are two main problems with underwater operations of starships.

The first one is the fact that almost all Traveller designs would lack the
weight to submerge, they would just float unless they had ballast tanks
or would flood their cargo holds - not necessarily a good idea.

The second one is the lack of sonar sensors, because all sensors descri-
bed as normal starship sensors would work badly or not at all in an under-
water environment.

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.

 

[far-trader]

There are two main problems with underwater operations of starships.

The first one is the fact that almost all Traveller designs would lack the
weight to submerge, they would just float unless they had ballast tanks...

...like the huge percentage of volume and equipment most starships have in the form of fuel tanks that can routinely dip from said aquatic environments I agree most commercial ships would float and getting them to submerge would not be easy (perhaps impossible). But most military ships would sink, getting them to float would be a trick (using the fuel tanks for positive ballast might be enough).

...or would flood their cargo holds - not necessarily a good idea.

Agreed, and unnecessary with a full (or nearly) cargo hold. The contents would have a higher density than water.

The second one is the lack of sonar sensors...

Not really evidenced (the lack of) in some design systems, and optional in others.

The game has long had starships submerging, depth of operations being tied to armour generally, but no special modifications beyond streamling required.

This says to me that streamlining includes among other things additional sensors (not just for underwater but atmospheric all weather ones as well, which unstreamlined ships would never find use for) and other control surface features.

Nor are weapons apparently designed for single condition use but a wide variety of environments. Vacuum, atmosphere, gas giant upper atmosphere and other thin atmospheres, dense atmospheres, and even corrosive and insidious atmospheres. With ortillery usage common.

The one thing I will grant is the artistic takes on a number of hulls would render them awkward in submersible use. That'd be a ref call on a situational basis. Not if they can but how difficult it would be.

 

[rust]

...like the huge percentage of volume and equipment most starships have in the form of fuel tanks ...

True, but the ship would have to get rid of most of the fuel to use the fuel
tanks as ballast tanks, and filling the fuel tanks with dirty sea water would
at least force the crew to clean the tanks very well before they are used
again for fuel - otherwise an engine failure or a misjump could be very like-
ly ... I doubt that jump engines are built to handle plankton and salt ...

 

[CosmicGamer]

True, but the ship would have to get rid of most of the fuel to use the fuel
tanks as ballast tanks, and filling the fuel tanks with dirty sea water would
at least force the crew to clean the tanks very well before they are used
again for fuel - otherwise an engine failure or a misjump could be very like-
ly ... I doubt that jump engines are built to handle plankton and salt ...

Doesn't water = unrefined fuel? If the water is taken into the 'ballast' (fuel tanks) the same way it normally is, I assume through filters, when refueling, I don't see the problems...

The problem I see is that under normal conditions a ship should be able to float and not sink with full tanks after refueling. IMO, some other means of getting the ship to 'dive' must be employed beyond filling the fuel tanks.

 

[flykiller]

The game has long had starships submerging, depth of operations being tied to armour generally, but no special modifications beyond streamling required.

This says to me ....

it says to me "massive handwave". since the original question in the thread was "is this actually possible?", the answer is no, not without some serious rule additions and clarifications. which is, of course, a primary referee function.

as for a ship submerging, all it needs is a maneuver drive pushing it down. now, if your maneuver drive is a fusion rocket this may create issues, but if it's a "reactionless thrusterplate" then it's no problem at all.

After all, aren't standard starships rated for insidious gasses like hydrogen (gas giant atmosphere) and corrosive atmospheres?

near as I can figure, this is another handwave. the ships are simply "rated", and the engineering requirements and limitations that would in fact make it so are ignored. whether to leave it as a handwave, or to try to come up with reasons and engineering to make it actually work, is a referee decision.

 

[rust]

Doesn't water = unrefined fuel?

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.