Traveller 1977: How Many Ships?

Before we address the question of who owns all those naval and scout bases, how many starships are in the subsector? The 1977 edition of Traveller is a game of small, standardised starships, up to 5,000 tons. We’ll talk about why that is later, but how many starships are there?

Let’s conduct a thought experiment. In an average subsector, there are 40 worlds (assuming a 50% chance of one per hex). Of these, 7 have class A starports, 10 class B, 12 class C, 4 class D, 6 class E, and 1 class X.

Imagine that our PCs’ ship arrived simultaneously at each world. Based on the 1977 Book 2 encounter table, how many ships of each kind would it encounter? For example, there’s a 9/36 chance of encountering a free trader at each of the 6.67 class A starports, so on average there are 1.67 free traders in space near class A ports that day. Repeating this calculation for all ports and encounter types gives the number of ships available for encounters on that day – it takes 20 hours to reach the jump limit, and presumably a similar time to land, so these figures are probably not far off the number of ships that are between the ground and the 100 diametre limit on any given day.

A hyperspace jump takes a week, and on average ships stay in port for a week, so the vessels available for encounter in space represent roughly 1/14th of those in the subsector.

Total shipping by type in an average subsector, then:

  • 180 Type A Free Traders. You can find these anywhere except class X starports, and they are the only ships that visit class E. They’re the starfaring equivalent of a bush pilot in a DC-3 Dakota.
  • 50 Pirate ships, of which 21 are Type S Scout/Couriers. 21 are Type C Cruisers, and 8 are armed Type Y Yachts. These spend most of their time at class A or B starports, presumably because that’s where their prey is, but are sometimes found at class C or D.
  • 60 Subsidised Merchants, which are a mixture of Type R and Type M; the Type R vessels roam around clusters of worlds, while the Type M shuttle between those clusters. I suspect there are more Type R than Type M, but the optimum ratio will depend on the density of worlds in the subsector.
  • 17 Type Y Yachts which are not pirates or patrols. These are only found at class A and B starports. However, they must travel to other classes of starport because they only have jump-1 drives, so when they are out in the boonies they either act as patrol vessels or pirates, suggesting that yachts are routinely issued letters of marque.
  • 32 patrol vessels, of which 5 are armed Yachts, 13 each Scout/Couriers and Cruisers, and the remaining one could be any of them. These are mostly found in the same places as pirates, and for the same reason – that’s where their prey is (pirates). However for some reason they don’t care about class D starports enough to show the flag.
  • Total, 340 vessels; 53% are Type A, 18% mixed Type R and Type M, and there are roughly 10% each of the other types. This is enough to make it credible you have never heard of a specific ship before, but not so many that it’s unlikely.


  • There’s a good reason the Type A is the iconic Traveller starship; there are more of them than all the other types put together.
  • On an average day, there are 7 starships grounded at a class A starport, 6 at a class B, 4 at a class C, 3 at a class D, maybe one at a class E if you’re lucky, and none at a class X. So starports are probably smaller than you thought.
  • Class D starports are probably pirate havens, because pirates go there but patrols don’t. They are also the most likely to have a scout base, but any Type S you meet there is a pirate. This is the point where you start to wonder if the scout service and the pirates are connected somehow.
  • You are roughly twice as likely to meet a pirate as a patrol, except at class A starports where there are roughly even numbers of both. This is no doubt why most starships are armed.
  • 60% of scout/couriers are acting as pirates at any given time, and the rest are on patrol.
  • Yachts act as pirates or patrols when they are not in systems with class A or B starports.

The 1981 edition of the rules has a different and more complex encounter table. Amongst other changes, pirates never appear at class A or B starports from 1981 onwards, and they are much less common in general. I prefer the 1977 table.


Spreadsheets make this much easier to do now than in the 1970s, when I relied on calculators, mental arithmetic and a login script to harvest passwords from students in other departments who weren’t using all their computer time allocation… pity to waste it…

The 1977 edition of the rules paints me a picture of a subsector where ships turn pirate at the drop of a hat if they think they can get away with it, which means other crews are a lot like the PCs. Anybody in a Type C, S or Y is not to be trusted; even if they’re not pirates (and are you sure you can tell?) the rules explicitly say that patrols may be legalised pirates demanding tolls from incoming traffic. Also, starships are rare items; there are only a handful at the starport, and only a few hundred in the subsector as a whole.

Is this the game universe Marc Miller intended? Probably not; published discussions with him suggest a referee more interested in the spirit of the game than in following the Rules As Written to the letter, and a setting which in 1977 was a frontier region just beyond the boundaries of a large empire.

Is it the game universe that the Rules As Written imply? Yes, I think it is, and I think it’s an interesting one. So let’s roll with it a bit further and see where that takes us.

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