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Life Support

This was the featured article in the February 2013 issue of the magazine.

My recent Traveller campaigns focus on exploration, military or ‘adventuring’ activities, neglecting mercantile ones. This is mainly due to the temperament of my group, which loves mysteries and combat (starship or otherwise), but hates dealing with ‘small stuff’ such as economics and life support. Searching for a way to simplify some bookkeeping, I developed the following method.

It should be noted that these house rules do not accommodate small craft, nor do they take into account the requirements of non-human lifeforms, as my current campaign rarely deals with them. They are based on the Mongoose Traveller rules (which I currently use), but should be easily modified for other Traveller rules systems.

I first reduced the size of standard staterooms to 3 tons, removing the portion allocated towards life support equipment (as per the standard Traveller rules). I left the sizes for cabins untouched, as these are much smaller and do not contribute a significant portion of a ship’s life support equipment (though I do reduce the cabin’s base price by a small amount). Suites or luxury staterooms are also unchanged. After all, these are suites; they should be larger. I then reduced the prices for these components to reflect the removal of the life support equipment (again, leaving suites unchanged).

Next I created ‘Life Support Units’ (LSUs). I used a 10-stateroom capacity as the initial basis for the standard unit, making it 5-tons in size and costing MCr 2.5. This is of course the perfect capacity for a free, far or fat trader. (Well, not quite enough for the fat trader’s 13 staterooms, but close.)

In determining the life support capacity for the standard unit, I computed 28 man-days capacity for ten staterooms (280-days), and rounded up to 300 man-days (representing a small efficiency bonus). To allow for double occupancy (per the standard Traveller rules), I increased this capacity by 50% (to 450 man-days), using the assumption that most staterooms will not be run at double occupancy for more than a couple of weeks at a time.

Using these numbers, a standard Life Support Unit requires 5-tons volume, costs MCr 2.5 and provides 450 man-days of life support. I then created larger and smaller sized units and extrapolated their tonnage, cost and support, as listed on the chart below. I considered creating even larger units (huge or military size LSUs), but ships large enough to require larger units are hardly ever encountered by my players, so I left these untouched.

For standard ship designs in my campaign, I make the assumption that these units are already installed (with an appropriate-sized LSU), and make no changes to the ship’s layout or cost. Newly-designed or customized ships reflect these changes.


Quarters and Life Support Units
Unit Type Volume (dT) Cost (MCr) Notes
Luxury Suite 8 1 or more  
Stateroom 3 0.25  
Cabin 2 0.15  
Large LSU 10 5 900 man-days life support
Standard LSU 5 2.5 450 man-days life support
Small LSU 3 1.5 225 man-days life support

LSU Refills

Naturally these units need restocking. I set the cost for a standard-size LSU refill at Cr 30,000, and adjusting the cost as appropriate for the other unit sizes. In addition I set ‘arbitrary’ sizes for the volume of these supplies. Note that these sizes may not be accurate for some Traveller rules, but they work for my campaign, and the players in my group don’t seem to have any problems with them (or haven’t exposed any issues. Yet).

These refill kits include not only food and air, but other necessities such as replacement filters, life support-specific spare parts, new seals, replacement air tanks and the like.

Refill ‘kits’ can be purchased and stored in the cargo bay, and used as needed. Note that the 100-day Kit provides air, stock food and a few replacement filters; it does not supply the regular LS-specific spare parts, and is used by captains or stewards to ‘top off the stores’.


Life Support Unit Recharges
LSU Refill Type Cost (Cr) Volume (dT) Man-days support
Large LSU 60,000 1.00 900
Standard LSU 30,000 0.50 450
Half Unit or Small LSU 15,000 0.25 225
100-day Kit 6,000 0.10 100

New Ship Statistics

I add two new ship statistics for these house rules: Life Support Capacity (LSC), which has two values, and Standard Duration. Use of these numbers allow a ship captain to compute when, how often, etc., he will need resupply.

Life Support Capacity has two values: Standard and Maximum. The Standard LS Capacity is calculated as follows: +1 per cabin; +1 per stateroom; +2 per suite. The calculation for Maximum LS Capacity is as follows: +1 per cabin; +2 per stateroom; +4 per suite. For example, the Beowulf-class free trader has a Standard LS Capacity of 10 (10 staterooms), and a Maximum LS Capacity of 20.

Standard Duration is the average, expected duration of the LS Unit in days. Divide the ship’s Man-Days of life support by its Standard Capacity. For instance, the Beowulf-class free trader’s Standard Duration is (450 / 10) 45 days. If a Beowulf runs at double occupancy its duration is a mere 22.5 days.

Overloading Life Support

In certain situations a ship may be forced to carry more passengers than it is rated for; for example, deep space rescues. As noted, standard Traveller rules allow for double occupancy without stress to the ship’s life support systems (but at an additional cost). However there are times you just don’t want to leave someone behind; you may need to overload the system to save lives. These house rules allow for this! But it comes at a price…

As stated above, ships may carry up to their rated Maximum LS Capacity without complications. If a ship is carrying persons over its the Maximum Capacity, make an 8+ roll each day to avoid a life support malfunction with the following modifiers:


A deep-space rescue might be the sort of situation that would require life support calculations to come into play:

Captain Smith, owner of the Beowulf-class free trader Emperor’s Dream, has come out of jump in a system, and has picked up a distress signal. Another free trader has collided with a planetoid, resulting in severe damage to its power plant. That ship’s engineer has managed to rig a solar collector, and maintained enough power to keep the crew and passengers alive. But the system is degrading quickly.

Fortunately, Emperor’s Dream is only a day’s travel from the stricken ship. Captain Smith overtakes the distressed vessel, matches course and docks. The Emperor’s Dream is carrying a crew of four, 20 passengers in low berths (so these are unavailable for the rescued crew and passengers), and six passengers. The damaged ship, also a free trader, has four crew, four passengers and six passengers in low berths. Captain Smith squeezes everyone into the ship, then bolts for the main world, two days travel away. (Smith could have pulled the low berths out of the damaged ship, but his cargo bay is completely full; it was a good stop at the last planet.)

The Emperor’s Dream, a standard free trader, has a normal Life Support Capacity of 10, with a maximum of 20. It also has 365 man-days of life support remaining (having just restocked at the last stop). With the current crowding of 28 persons (14 original occupants plus 14 more from the damaged free trader), the Emperor’s Dream’s life support system will be stressed until it reaches the main planet (or another nearby ship). With the engineer’s Engineeer (Life Support) skill of 1, no EDU bonus, and DM –1 penalty for the overcrowding, the ship’s engineer must roll 8+ per day to maintain the life support unit. The ship will also use 56 man-days of life support for the two-day trip. The overcrowding and chance of malfunction are a small price to pay for saving the lives of 14 persons.