On Wed, Mar 30, 2016 at 05:40:58PM +0000, Bruce  Johnson wrote:
> Yet this is not reflected in real-world experience: the trend has
> been to ever-larger container ships rather than more of them.
>
> Why?

Real-world ships do have many economies of scale that Traveller ships,
at least per the published design and operation rules, do not.  High
in these are fuel costs, which in turn depend upon the various sources
of hydrodynamic drag with various scaling laws.  All of these work out
to less than linear per unit volume.  Much weaker economies of scale
come with efficiencies of larger scale engines, maintenance, capital
costs, and crew requirements.  There are also a few diseconomies of
scale, mostly driven by port and canal capacities.

Traveller starship costs are not dependent upon drag at all, and their
fuel costs per unit volume are essentially constant.  Efficiency is
mostly irrelevant, while all of the other costs I listed work out to
be pretty closely proportional to jump drive size for all but the
smallest ships.  So once you get a few small overheads out of the way,
cost per unit freight volume is pretty much constant for a given route
for ship sizes from ~3k dtons up.  The exact threshold depends upon
how many decimal places you care about.

This could be changed with different construction and operation rules,
of course.  The purely linear relation of fuel consumed and jump drive
cost to volume of ship is the main factor driving the lack of
economies of scale in large ships.  If you tweaked them to be
supralinear, you get a mostly small-ship universe.  Sublinear, and you
get enormous superfreighters.  The easiest way to arrange the latter
would be for one or both of the costs to be proportional to the hull
area, rather than the volume.

- Tim