Friday, January 1, 2021


Mothership's default ship creation rules are not its strong suit.  They feel like a bit of GURPS slipping into an otherwise elegant OSR-style game.  This is a first attempt at codifying a better system using tables and a bit of abstraction.  

Right now I've built this around my default assumptions surrounding the cost of space travel.  MoSh's default assumptions about the cost of ships are not conducive a setting with space truckers and privately-owned starships transporting bulk cargo.  If an escape pod costs 300mcr and a credit buys some arbitrary amount more than a 2020 dollar, you're not transporting anything other than magical unobtanium at a profit.  

Instead, let's set out some assumptions. 


A MoSh credit is worth somewhere between $1 and $5 USD.  I'm going to use $4 for this article -- that makes an oxygen tank about as expensive in MoSh as IRL, a vacsuit is implausibly cheap, and a submachinegun is implausibly expensive.  Eh.  Close enough. 


There is a fairly narrow range of economically-sized spacecraft dictated by trade routes, technology, and the industrial capacity of a retrofuture polity/corporation.  Hull and operating costs scale linearly.  Jump drives have a fixed cost regardless of the size of the ship.  The numbers I use are based on my own setting.  Use this as a guide rather than a bible.


TINY spacecraft cost about 25mcr ($100 million) -- this reflects SSTOs, dropships, yachts, and other similar ships. They have a useful payload of 100 tons or less.

SMALL spacecraft cost about 100mcr ($400 million) -- this reflects in-universe equivalents to ships like the Firefly, Millennium Falcon, and various other small freighters.  They have a payload of approximately 400 tons (or less). 

MEDIUM spacecraft cost 200mcr ($800 million) -- this probably reflects the optimal space cargo ship.  They have a payload of about 800 tons.  Much bigger than a cargo airplane but much smaller than a cargo ship (because bulk cargo is far too expensive to profitably transport).  You could fit thousands of frozen colonists on a ship this big or a sensible load of high-value goods

LARGE spacecraft are twice as heavy and twice as expensive as medium ships ($1.6bn)

HUGE spacecraft are four times as heavy and four times as expensive as medium ships ($3.2bn).

MASSIVE ships are the equivalent of aircraft carriers, oil rigs, and other really big structures.  There is no open market for them so they cost as much as you want them to.  For what it's worth, aircraft carriers cost around $10 to 15 billion IRL.  


Jump drives always cost 50mcr.  Prototype jump drives that outperform standard models are not available on the open market.  If you find such a drive, many people will kill you for it.  

100 ton of weapons system always costs 5mcr (this is a recurring expense if you use torpedoes, missiles, or other self-contained weapon systems) -- this includes extra radiators, fire control systems, power, etc.  

Fuel has a negligible cost -- it's just hydrogen or water and -- like Traveler -- you can refuel in the field if need be.


Between operating costs and a standard 20-year spacecraft mortgage, a spacecraft owner will pay 10% of their ship's value per year in insurance, maintenance, and interest.  Used ships cost the same to maintain -- you have to pay in increased maintenance and insurance (or die).

Principal is amortized over the course of the 20-year loan.


The tramp freighter R.V. Efficient Capital Meerkat is a MEDIUM spacecraft with a jump drive and space for 800 tons of freight.  Therefore, it costs 250mcr if you happened to have the MoSh equivalent a billion dollars in cash lying around under your sofa.  

For everyone else, the ship costs a (relatively) reasonable 37.5mcr per year.  They will have to come up with the first year's payment up-front.  That's a lot of money ($150 million per year) but space travel is quite profitable and in corporate space you can easily sell equity in a ship without worrying about annoyances like securities regulation.  There are many specialized hedge funds that love taking large stakes in questionably legal tramp freighters.  Just be sure to share the proceeds of your illegal activities with them.  That's why the bought the stake in the first place. 

Assuming that the Meerkat can make six trips per year (unlike a corporate freighter it has to spend a while in port to fill its holds), its skipper must find  6.25mcr of cargo to break even.  If somebody wished to charter the ship for about 2 months, that would cost the same provided the work was boring and safe.  

We also know what types of cargo the Meerkat will be transporting.  To break even, the skipper must charge about $30/kg (7.5cr/kg).  Therefore, consumer electronics, finished components, and valuable natural resources such as gold, platinum, and enriched uranium will all move.  So will luxury cars, racehorses, wine, and bougie furniture.  On the other hand, steel, grain, and ordinary automobiles aren't profitable.

If we assume that a person in a cryopod weighs 250kg, we also know how much a passenger ticket costs! ($7,500 or 1,875cr).  

If you're really pedantic, you can estimate how much cargo comes in to every planet or colony.  I don't recommend it and won't go there.

In any event, at a typical port it's fairly easy to find 6.25mcr of value-dense cargo.  On the other hand, it's also hard to find much more than that without taking some risks by transporting cargo that is illegal, dangerous, or attractive to pirates.  To make a profit you need to take risks! 


My next post in this series will address how to go about finding cargo in a port and will have some random tables to give you an idea of what you might find in any given port.

While I'm inclined to handwave things like ship combat, some of you may not be.  I'll give you the tools to convert my size categories into hull points so you can blow other peoples' ships up.  We'll also address weapons.


  1. What are the tools for converting cargo hull points into tons like if my crews ship can carry 100 cargo how many tons is that and how many pallets make a tone

    1. There aren't any. 0e Mothership's hull sizes are, essentially, nonsensical and the system isn't actually much fun in combat. The typical 0e ship is *colossal*; bigger even than large boats and a comparison wouldn't be meaningful.

      I personally don't use ship stats at all; my players *never* have the benefit of a warship. Cargo capacity and Delta-V are the only numbers that matter at my table.

      Tons are the relevant unit. You might also think in terms of 20-foot shipping containers. Those have a maximum gross mass of about 25 tons (but unless they're carrying very dense stuff, usually only a fraction of that).

      The Efficient Capital Meerkat can carry 800 tons of stuff. And charges freight rates by the ton. That's somewhere between 32 and 64 20 foot containers. Or, alternatively, about six 747s worth of cargo. By the standards of planes, a lot. By the standards of boats, not much at all.

  2. Oh, and as to the mentioned tools (lol), I've overpromised and forgot that little line at the end of this post until the very end.

    While I can't say I recommend it, you could divide payload capacity by 200 to get a roughly appropriate number of HP. 40 for the Meerkat. 80 for a large cargo ship, and 160 for a huge ship.

    Really big spacecraft don't really warrant HP at all.