How to stat 20 minutes of Vacuum Support?

[acrosome]

Trying to stat Luriani (a variant Humaniti) under 4ed rules.

Luriani can store oxygen in their tissues to the point that they can stay underwater not breathing for up to an hour, so 3200 seconds is close enough to 3600 seconds (at HT10), call it Breath-Holding 5 [10]. For the sake of realism I also added Takes Recharge, 15 seconds, -20%, for total cost [8].

They also have Nictating Membrane 1 [1].

By Traveller canon they can even survive in vacuum up to 20-30 minutes, the duration being limited by water loss and temperature rather than oxygen. So that sounds like they do not have Sealed [15]- I'm on top of that.

But GURPS Vacuum Support [5] does not have a duration. How do I give it a duration? Advantage modifiers cannot reduce cost more than -80%, and it seems like going from infinite duration to 20 minutes might max that out, but that would drop the cost to only [1].

Does that seem right? That seems rather cheap for a scifi setting, vacuum being common and all.

Or should I be doing this some other way? Having read the rules for Vacuum on p. B436-437 I could make an argument for no Vacuum Support, since that would protect from the effects of explosive decompression, presumably, and that's probably not applicable. And under RAW in a vacuum you can operate for half the time that you usually can on stored oxygen, which with Breath-Holding 5 and assuming HT10 comes out pretty neatly between 20 and 30 minutes, anyway.

[johndallman]

I'd take the Breath-holding, as you have it, but I'd give it a much longer recharge time. Getting that much oxygen into the lungs, bloodstream and storge should take rather longer than 15 seconds.

I'd take the basic Vacuum Support [5], without Sealed, and reckon that the Breath-Holding was setting the limit. A way to test the validity of this:

What do you reckon happens to one of these people if they're exposed to vacuum, but have an oxygen mask and can maintain a reasonable temperature, via a non-sealed suit? I reckon from your description they're OK until the dehydration from the lack of Sealed gets serious; with a water supply they might last for days.

However, I'm not familiar with this Traveller race, and might be missing something.

[acrosome]

Originally Posted by johndallman

I'd take the Breath-holding, as you have it, but I'd give it a much longer recharge time. Getting that much oxygen into the lungs, bloodstream and storge should take rather longer than 15 seconds.

I had thought so, too, but the next recharge step is 1 hour. And whales and seals don't seem to need very long surface stops, so I went for the shorter option.

The steps for Needs Recharge are:

5 seconds -10%
15 seconds -20%
1 hour -30%

So I suppose that I could make up some duration for -25%... Maybe 5 or 10 minutes? There really should be one between 15 seconds and 1 hour.

Originally Posted by johndallman

I'd take the basic Vacuum Support [5], without Sealed, and reckon that the Breath-Holding was setting the limit. A way to test the validity of this:

What do you reckon happens to one of these people if they're exposed to vacuum, but have an oxygen mask and can maintain a reasonable temperature, via a non-sealed suit? I reckon from your description they're OK until the dehydration from the lack of Sealed gets serious; with a water supply they might last for days.

My issue with Vacuum Support is the protection that it provides from explosive decompression, which can otherwise blind eyes and injure ears per RAW. Though Luriani have Nictating Membrane and can seal their ears for diving deeply into water, I don't think they'd be immune to explosive decompression. The +1HT for the Nictating Membrane to avoid the blindness (rolled separately for each eye) seems like enough. I might even just add a 0-point special effect that they get +1HT against the hearing loss, too.

Originally Posted by johndallman

However, I'm not familiar with this Traveller race, and might be missing something.

They're humans modified by the Ancients to be somewhat amphibious. They are different enough that they are not fully interfertile with humans- they tend to produce mules with cognitive deficits. Opinions differ on whether this makes them a different species, Homo luriani versus Homo sapiens luriani.

If you look at TravellerMap.com and find the blue special cultural zone close to the Imperium's trailing border in Ley sector, that's the Luriani zone. So they are one of few groups (like Syleans, Lancians, etc.) to have a special cultural zone within the Imperium. In their case it is because they all have 3D Spacial Sense and thus make magnificent spaceship pilots, and they managed to kick the Imperium's ass while resisting forcible annexation at one point, but then later bargained for special cultural status if they allowed annexation willingly. They are easily the least assimilated of the special cultures in the Imperium. By Imperial standards they come across as overly-emotional extroverts, if not outright hotheads.

My daughter likes them. And frankly, they are one of the better-designed variant humans. Most of the rest of humaniti (and most aliens, too) were obviously designed by a 14-year-old trying to make something "kewl".

[DangerousThing]

Another thought: they aren't holding their breath, but storing it in their tissues. There wouldn't be enough internal pressure to allow them to explosively decompress. The membranes would protect the eyes and biology the rest of their body for at least. 20-30 minutes.

I also believe it would take much longer than 15 seconds to recharge. I'd think about prep time rather than recharge.

[johndallman]

Originally Posted by acrosome

The steps for Needs Recharge are:

5 seconds -10%
15 seconds -20%
1 hour -30%

So I suppose that I could make up some duration for -25%... Maybe 5 or 10 minutes? There really should be one between 15 seconds and 1 hour.

I think I've found better ways to handle this:

Originally Posted by p. B115

five seconds
(or twice the time required to use the
ability, if longer) is -10%, 15 seconds
(or 5 times the time required to use
the ability, if longer) is -20%, and one
hour (or 10 times the time required to
use the ability, if longer) is -30%.

For this, read "time required to use the ability" as "time you've been holding your breath", and you get a choice of recharge rates, plus recharge time scaled to the time for which you used the ability, which makes sense.

Alternatively, take Doesn't Breathe (Oxygen Storage), p. B49, which is actually closer to the described mechanism, and give it Takes Recharge with the interpretation above.

My issue with Vacuum Support is the protection that it provides from explosive decompression, which can otherwise blind eyes and injure ears per RAW. Though Luriani have Nictating Membrane and can seal their ears for diving deeply into water, I don't think they'd be immune to explosive decompression. The +1HT for the Nictating Membrane to avoid the blindness (rolled separately for each eye) seems like enough. I might even just add a 0-point special effect that they get +1HT against the hearing loss, too.

Fair enough.

They're humans modified by the Ancients to be somewhat amphibious. . . . frankly, they are one of the better-designed variant humans. Most of the rest of humaniti (and most aliens, too) were obviously designed by a 14-year-old trying to make something "kewl".

Thanks!