TONNAGE BLUES, or Afloat on a Sea of Liquid Hydrogen
We'll probably never come up with the real reason that Traveller elected to
use a definition of tonnage volume based on liquid hydrogen, all those long
years ago. However, as anyone who has fooled around with vehicle designs will
tell you, even under High Guard starships were frequently 50% or more fuel
by volume. This makes it not wholly unreasonable to base your rating system
around a fact which is almost as pervasive as the weight of water is in the
real world.
Rob Dean