Depressurization Rules

TerlObar

November 3, 2017 - 6:51pm

Another tidbit from my Assault Scout write-up. This time dealing with the specifics of depressurizing the ship. These are specific for the ship but are easily adapted to be general for any ship.

Typical procedure is to fully depressurize the ship prior to any sort of engagement that might involve ship combat. This is to prevent explosive decompression of the ship or sections of the ship in the event of a hull breach. By depressurizing the ship in advance crew and repair robots can move freely through the ship as needed.

All rules for an airless environment apply once the ship is depressurized. Everyone had better be in spacesuits.

Standard decompression

It takes four to six minutes to properly empty the ship of air. During this time, equipment is sealed, the plants in the hydroponics section are sealed in airtight containers and the air is pumped out of the various ship compartments and stored in atmospheric storage tanks that are part of the life support machinery.

For most decks of the ship, it takes one minute for the systems to shut down and seal themselves properly to withstand the vacuum of space. After that it takes 3 minutes to evacuate all the air from the deck. Each cabin has one or more airtight containers installed. Anything that cannot handle exposure to vacuum should be stored in these containers prior to the start of this process. Anything not properly stores will sustain appropriate damage.

The deck with the active hydroponics systems takes 2 minutes longer. These systems have special container systems that seals up as part of this decompression process. The sealing of the plants takes the first 3 minutes of the decompression process. After which, it takes another 3 minutes to evacuate the air from the deck. If this sealing process is skipped or not completed before the actual depressurization starts, the plants will die effectively reducing the duration of the life support on the ship by a month.

Rapid decompression

The above assumes that the crew is trying to capture the air in the life support system to reuse later. If the crew wants to just vent the air to space, the ship can be emptied in 30 seconds (5 turns) by overriding the safety systems, opening all elevator and ladder hatches and then opening the cargo bay, air lock, and ship's launch bay doors to vent the air to space. Evacuating the ship this way reduces the available life support duration of the ship by a month.

Any being or robot in the room with one of these external hatches or by an open elevator or ladder well hatch must make a STR roll if they are not attached to something via a tether or magnetic boots to avoid being knocked off balance and through a hatch by the outrushing air. If they fail, they immediately take 1d10 points of damage from being bashed around. If they can make a DEX roll, they manage to grab something and avoid being swept away. Any character strapped into an acceleration couch is automatically safe.

If they fail the DEX check, the referee should determine how far away they are from an external hatch. Depending on the number of decks away they are from the external hatches, they may more opportunities to catch themselves. For each opportunity they have, they take 1d10 point of damage and then can roll to make a DEX check. If they succeed, they catch themselves and take no further damage and remain on the ship. If they fail all of their checks, they are swept out of the ship. Consult the following table to determine the number of attempts available based on distance from the hatches.

Distance from external hatch	Number of save attempts
same cabin	1
same deck but different cabin	2
2-3 decks away	3
4+ decks away	3*
* even if they fail all of their checks, they remain in the ship as the wind doesn't have enough force by the end to carry them away. They still take 3d10 points of damage though.