How deep can you go?

[Fovean]

I've been playing around with this problem for a bit...

Doing a little Wikipedia research led me to create a table of pressures for different depths on an Earth-like world, as well as different pressures for Large/Small Gas Giants and Ice Giants.

Pressures in the GGs range from 0 to appx 300 Atmospheres for the various layers, with the first real "skimmable" layers beginning around 1 Atm. I've ruled the deeper you skim, the less skimming and refining time necessary but also the more difficult for the Pilot and increased chance of Hull hits on a failed Pilot task.

The Pressure of water on an Earth-like planet gets intense rather quickly so I had to do a different rule. Anyway:

In GG or similar atmos: Crush Depth = (Structure + Armor)^2

In water/fluid oceans: Crush Depth = (Hull + Structure + Armor)^2

Rating in Atmospheres (1 Atmosphere = Surface of Earth pressure)

In all cases, multiply Pressure by local gravity for true Pressure

This allows a basic Free Trader to skim past Ammonia and Methane Clouds down into Water Cloud layers and save a lot of refining time but it's dangerous; the Free Trader can also dive in an Earth-like ocean to appx the lower Twilight Zone/Upper Midnight Zone (appx 1200m).

Doesn't account for buoyancy though, and rust makes a good point about hull configuration. But this is quick and easy (now that the chart is built ) and gives some good crunch.

 

[SSWarlock]

I've been playing around with this problem for a bit...

Doing a little Wikipedia research led me to create a table of pressures for different depths on an Earth-like world, as well as different pressures for Large/Small Gas Giants and Ice Giants.
<snippage of good stuff>

Oh, I like this. And while I agree with your comments about rust's point regarding shape, MGT unfortunately doesn't separate out spherical design from other "standard" shapes. Though I suppose since the shapes are mentioned, I could go with your formulas, Fovean, modified by the following SWAGs:

Distributed -> Crush Depth x 0.1
Sphere -> Crush Depth x 1.5
Cylinder -> Crush Depth x 1
Wedge -> Crush Depth x 0.75

Any comments to help make the above modifiers a bit more realistic would be welcome.

Um..I don't suppose you'd mind posting your table?
*hopeful look reminiscent of Puss In Boots' large eyes in Shrek*

Edit: Question for Fovean..are your Crush Depth formula results in meters or tens of meters?

 

[rust]

I think I would give a sphere a crush depth x 1.5 and a cylinder a crush
depth x 1.2 and all others a crush depth x 1 to keep it simple.

 

[SSWarlock]

Simple is good. My goal is to emulate, not simulate, reality while maintaining playability and Maximum Game Fun(tm).

 

[RichardP]

The Challenge mag had a series of design rules for watercraft using the MT design system. Max dive depth was 15m per 1pt of MT armour. Under those rules a basic comerical starsuip had hull armour of 40 giving a max dive depth of 600m.

The dragon SDB has a CT high guard armour of 9, which is (9*3)+40 = 67 under the MT rules. That gives about 1km depth (okay 1005m) 1km of water will stop of lot of sensors and energy weapon fire.

So 1 km depth puts SDBs on the bottom on the continental shelf area but not on the seabed mid ocean?

Cheers
Richard

 

[rust]

So 1 km depth puts SDBs on the bottom on the continental shelf area but not on the seabed mid ocean?

Yep, most of the abyssal plains are at a depth of about 3,000 meters.

 

[Solomani666]

My quick and dirty rule would be:

(Hull Armor + 1) * Surface Gravity * 1000 m = Crush Depth


Note:
IMTU the outer airlock doors are armored to the same level as the hull.

Let me know if this seems about right to you.

After reading some of the replies, perhaps this may be more realistic:

(Hull Armor + 1) * Surface Gravity * 500 m = Crush Depth

I like the idea of incorporating a world's Surface Gravity in the formula so that it can be used for both underliquid situations and in gas giant atmos. I am confused on one bit though. The way the formula reads now, it seems to be that the higher the Surface Gravity, the deeper the Crush Depth.

For example, a merchant with armor of 0 on a heavy gravity planet of, say, 2 Gs derives its Crush Depth as:

CD = (0 + 1) * 2 * 500 m = 1000 m

On a 1G world, its CD = (0 +1) * 1 * 500 m or 500 m.

Shouldn't the formula evaluate so that the higher the Surface Gravity, the shallower the Crush Depth? That is,

(Hull Armor + 1) / Surface Gravity * 500 m = Crush Depth

If not, what am I missing?

Also, how can Structure be incorporated into the formula? Doesn't deliberately buffing a ship's structure above the "standard" for a given displacement mean the structure can take more punishment without catastrophic failure?

DOOOHHHH! Somebody made a boo-boo.

Thanks for catching that one!



Final formula:

(Hull Armor + 1) * 500 / Surface Gravity = Crush Depth (Meters)


.

 

[SSWarlock]

As an aside, all this talk about crush depths triggered a memory of a rather useful (to me at least) article by Ken Pick that details gas giants and their use and dangers in a Traveller campaign.

The article is at Free Traveller. Specifically,
http://www.freelancetraveller.com/features/science/index.html

On the same web page is an interesting article on atmosphere components.

Now back to the original thread...

 

[Fovean]

Um..I don't suppose you'd mind posting your table?
*hopeful look reminiscent of Puss In Boots' large eyes in Shrek*

Edit: Question for Fovean..are your Crush Depth formula results in meters or tens of meters?

Thanks for the kind words, and thanks for posting the link to Ken Pick's great article at Freelance Traveller... I'd forgotten about that.

To your questions... my formulas result in Atmospheres, as in scuba diving or certain scientific measurements of pressure on a given body. So you need a table of ranges to apply the "Crush Depth Rating" to if you want ranges in meters or what have you.

My table of GG/underfluid ranges is arbitrary, based on what I wanted my players to be able to do and also a synthesis of info based on GGs in our own solar system.

If I can figure out how to post an image here I'll put up a screenshot in this thread, otherwise I'll post a link to photobucket and you can see it there. It will be a day or two as I've a RL project that will have me busy. The chart's not anything special really but it has been pretty cool in my little proto-Trav game

 

[Fovean]

Okay, took a long time but this is what I've been playing with...

CAVEATS:

*The MGT Range scale isn't refined enough to deal with this subject so this is a revised scale I've been using (obviously inspired by Megatrav...)

*I've arbitrarily decided ships can escape gravities equal to twice their Thrust rating. Oddly, DFW has suggested 2 x Thrust in his Hull Config thread regarding leaving planetary atmospheres... but we're coming at it from different sides of the same coin, I think.

*Not sure about gravity as you dive into a GG, probably it should increase more than I've indicated here, but that opens up a whole other can of worms...

Okay fellas - pick it apart and let's make something of this :wink:

http://s1216.photobucket.com/albums/dd370/Fovean/?action=view&current=GGPressures.png

 

[DFW]

*I've arbitrarily decided ships can escape gravities equal to twice their Thrust rating. Oddly, DFW has suggested 2 x Thrust in his Hull Config thread regarding leaving planetary atmospheres.

You need to reread my rule. :wink:

 

[rust]

Okay fellas - pick it apart and let's make something of this :wink:

Two ideas I would like to add:

The formula Hull + Structure + Armour seems a bit generous to me. I
would take 75 % of the result as the safe depth and 100 % as the crush
depth, and require structural integrity rolls for any depth between the
safe depth and the crush depth (which would also add a little tension
whenever the ship dives deep).

The hull configuration should have an influence. I would give spherical
hulls a modifier of +20 % and cylindrical hulls a modifier of +10 % to
the result of the formula of Hull + Structure + Armour.

 

[Fovean]

*I've arbitrarily decided ships can escape gravities equal to twice their Thrust rating. Oddly, DFW has suggested 2 x Thrust in his Hull Config thread regarding leaving planetary atmospheres.

You need to reread my rule. :wink:

Yes, sorry, was late and I couldn't be bothered to find the exact quote. Not my usual MO

rust, good ideas. I've already started rethinking a few things, mechanics-wise. I'll keep tweaking...

 

[SSWarlock]

(Cross-post from the "Hull Configurations - corrected" thread by DFW)

There was a discussion thread back in 2007 on the Citizens of the Imperium forum that went into some detail on the use of maneuver drives in gravity wells and gas giant skimming. It goes on for some length and does require a viewer to have a login (which is free) but there's some pretty interesting points made there.

Here's the link for anyone interested.

http://www.travellerrpg.com/CotI/Discuss/showthread.php?p=164034#poststop

The COTI discussion doesn't go into the detail like this thread does but it has some interesting general ideas on how to roleplay fuel skimming that may (or may not) be of interest so I thought I'd let everyone know. There's a similar archived thread on the GURPS Traveller forum but that requires a pay-to-access account so there's no point in posting that link.

 

[Fovean]

Thanks for the link, SSWarlock... I guess it's true that there's nothing new under the sun.....

 

[SSWarlock]

You're quite welcome..and sure there is! Your chart covering gas giant atmo pressures is the only one I personally have seen ever since I started playing Traveller. I can't tell you how many times I've wanted something like it in the past 30 odd years but could never find it.

The only thing I've seen that ever came even in the remote neighborhood was the diving decompression chart listed in The Underwater Environment CT supplement by GameLords Ltd. Nice for diving underwater but worthless for diving into a gas giant.