Breaching an Airlock

[Ubu]

So my group and I are very interested in boarding action in our campaign and have seen a few ways to go about it posted somewhere online, we tooled around with them a little bit.

Hacking: Making an appropriate DC Computer skill check to hack the ships computer, a PC can open the door without alerting the crew if all countermeasure are successfully bypassed.

Engineering: With an Engineering tool kit and appropriate DC skill check, a PC can manually open the airlock. If it is alarmed the crew will be notified, if there is a Science Officer active on the ship, they will become aware of the breach. DC can be based off of the hardness of the airlock (standard is 35) and some multiplication factor to make a cumulative check target.

I know there are basic DC checks ranging from 20-40 for opening a lock with engineering, but that is assuming the airlock actually has a physical lock on it.

Breaching Charge: With an Engineering skill check an explosive with detonator can be placed on the airlock, if successful the objects hardness is reduced by 1/2 for the purposes of damage. Explosives cost and have the same properties of grenades. This would always alert the crew.

Being the door kicking soldier I am very interested in using breaching charges though our operative has the hacking covered. The only problem with the rules in game for explosives vs airlocks is that the standard airlock has a hardness of 35 and has 160 HP so a single breaching charge, even properly set, must do 177 damage to breach the airlock. The maximum damage of 2 level 18 Frag Grenades worth 96,900c+100c for detonator a piece still fall short by 2 damage!

Is that math right? If so we need to do something about it. Maybe a feat that grants a multiplier to explosive damage when used against objects for demolition? Perhaps using an explosive focus as they do in real life for breaching charges could cause greater damage? Since the damage range for a Frag Grenade is 15 feet and we are reducing it to a focused point of say 1 foot, we could multiply it by 15 (I know not really how energy works but let’s look at the math).

A level 4 Frag Grenade at 700+100c for det does 2d6 or an average of 7 damage. Properly set with an Engineering skill check the 35 hardness is reduced to 17. So with average damage x 15 for being focused = 105 and after removing the 17 damage reduced from hardness, that leaves 88 damage on average per level 4 charge.

If that is too powerful we can factor in the tier of the ship to reduce the effectiveness of lower level explosives. For every tier above the level of the explosive subtract 1 from the multiplier? Add 1 for every tier the ship is below?

What do you guys think?

[Batgirl_III]

Buried under the Structures / Breaking Objects rules, you'll find this clause:

Quote:

Vulnerability to Certain Attacks: Certain attacks are especially strong against some objects. In such cases, attacks deal double their normal damage and might ignore the object’s hardness.

Obviously, its a question of GM's Discretion as to what those "certain attacks" are. But, I think its reasonable to assume that if the players have explicitly purchased dedicated breaching charges and are using them to breach an airlock, then they should benefit from this rule. Using bog-standard frag grenades won't do it.

[Losobal]

I dunno. I'd say it depends on state of airlock. Like...is the ship in space and the breach is happening from the void side? If so then the whole 'manually open the airlock while ship is flying through space' movie approach.

I believe usually the airlock would be kept pressurized.So you'd have the outer door a pressurized airlock, the inner door and then the pressurized inner ship.

I'm presuming the door would open inward, so the pressure of the airlock actually helps keep it secure (tons of pressure?) so hacking an airlock in this case would need to not only open the outer lock, but also first cycle the decompression of the airlock, and then hack the inner lock door. I can't see any scenario, other than 'undead ship and we don't care about air' where anyone would be silly/crazy enough to make their entire airlock system a 1-stage hack.

If we're going the scifi movie route were airlock doors are basically like elevator doors, I dunno. I'd still think you'd want a separate inner/outer system though.

I kind of feel you'd need to hack the primary system first to disable something like an airlock pressure sensor indicator, but not all ships would go to red alert if a depressurized airlock was noted, it might also just ping something on someone's screen on the bridge, if at all.

[Ubu]

For purposes of mechanics, we the hardness and hp values given for Airlock are for one set of the doors alone. An airlock is just like a real lock, 2 partitions used to equalize to what is held on the other side. So for our purposes this would require 2 breaches, one for the outer doors and one for the inner doors.

Obviously hacking is preferable as not only could it be a silent breach, but the doors remain operational. However blowing both airlock doors and exposing the unsuspecting bordies to vacuum may give the PCs an interesting edge in combat and an even more interesting fight. Personally, I think any crew that leaves their vessel pressurized in ship to ship combat deserves to asphyxiate for their poor planning.

My group settled on creating a feat to handle demolition:
Demolition Expert, Prerequisite Grenade Proficiency, Engineering rank 1 Benefit Explosives can be linked to a single detonator (taking the same time per charge) explosive damage is multiplied by 15 when used against objects.

Our GM has decided as per CRB that since charges are being specifically shaped for use in breaching, that DR is ignored and explosives do double damage. But as stated before, it would still take an obscene number of level 1 charges to breach a single portion of the airlock. However, if multiplied by 15 the average damage (3.5) x 15 = means you need just over 3 on average to breach an airlock door.

To make it scale, we decided to take ship tier into account. If you use level 1 explosive charges on a tier 6 ship, the damage multiplier is reduced by the tier difference. In this case it is reduced by 5 making the multiplier a 10 instead of 15. It also works the other way with higher tier explosives.

[William Leonharth]

Btw. You don't depressurize your ship during combat you just put on your spacesuit and helmet. Gundam teaches us well.

[Ubu]

William Leonharth wrote:

Btw. You don't depressurize your ship during combat you just put on your spacesuit and helmet. Gundam teaches us well.

I would argue that The Expanse teaches us better. Punch my ship full of holes with your anti-ship weapon, but if it doesn’t hit me I don’t care. Though I suppose if you depressurize your ship your atmosphere does need to be stored in high pressure tanks and would cause arguably much more damage if breached if the much smaller target is hit.

[Batgirl_III]

Sound general quarters. Everyone puts on their spacesuit and helmet. Everyone gets to their action stations. Disable artificial gravity on all decks. In any areas of the ship (that are not action stations or sickbay) you cycle out your everyday atmosphere for Anesthizine gas.

The Captain and/or Science Officer should have this pre-programmed as a hotkey on their duty console.

[kaid]

Advantage for venting or storing your O2 in preparation for a fight is fire control. No o2 no fires if everybody has space suits it would greatly reduce dangers of combat damage causing fires that could spread on the ship.

[Batgirl_III]

If you exchange your normal breathing atmosphere (which had better not be pure O₂!) with another gas is that you don’t change the pressure.

[WhiteWeasel]

kaid wrote:

Advantage for venting or storing your O2 in preparation for a fight is fire control. No o2 no fires if everybody has space suits it would greatly reduce dangers of combat damage causing fires that could spread on the ship.

The kestrel has taught you well.

Batgirl_III wrote:

Sound general quarters. Everyone puts on their spacesuit and helmet. Everyone gets to their action stations. Disable artificial gravity on all decks. In any areas of the ship (that are not action stations or sickbay) you cycle out your everyday atmosphere for Anesthizine gas.

The Captain and/or Science Officer should have this pre-programmed as a hotkey on their duty console.

I also nominate that we install a second gravity generator inverted relative to the primary one, and instruct the crew to buckle in or grab on to something before the Captain and/or Science Officer presses the hotkey that simultaneously powers up GG #2 and powers down the primary if the ship is successfully boarded.

[DecepticonZombie]

Size of your ship matters in this situation.
Small ships(anything that takes 10 people or under to effectively crew I'd think)would have an easy time at this. The volume and rates to depressurize or re-pressurize are not going to take a long time.
One also has to factor in crew readiness, training, and if the battle is a surprise or not.

As for the breaching/boarding aspects:
If I were to GM something like this, I'd probably do a loose interpretation of the rules/just handwave plausible options into effect.
I mean, a level 1 frag isn't going to pop an outer airlock door on anything larger than a small courier type ship, but a breaching charge would be able to handle most civilian level hatches/doors, either interior or exterior.
To me, stuff like this is more or less a GM discretion (mixed with common sense) type of situation. If it helps story and overall gameplay, I'm more open to rule bending. That's just how I see it.

[Ubu]

My group and I try to get any and all house rules agreed upon by all and written out since we rotate GMs after certain story arcs. One GM may be less prone to hand wave than another, so for us its good to have the numbers down.

On another note, being a technologically and magically advanced setting, some ships could easily have a Star Wars-like force field designed specifically to only hold atmosphere. This could negate the necessity of a secondary airlock strength door, replacing it with an interior ship door, or none at all for the frugal ship captain.

Personally I think it would probably make a better emergency system for a decompression event, but integration into other doorways and surfaces could probably be possible with little effort.