Rob the Vehicle MAven here, on the subject of duration:
As written the second duration number 30/*90* is functionally meaningless for
starships. For vehicles it makes sense because most vehicles are not intended
to be operated for more than 8 hrs a day due to driver fatigue. So to pull an
example out of the hat, a long distance truck with a duration of 2/6 could be
driven across the U.S. for 6 8 hour shifts before requiring refueling, assuming
that it is sitting in a parking lot, shut off, for the remaining time. A
starship can't really be parked with the engine turned off very often (except
at a starport, and even then in the Shattered Imperium I'd have it running
at low power to allow a warm start if I needed it.)
A recent issue of Traveller's Digest legitimized the concept of running your
starship at fractional power, with a proportional fractional fuel consumption.
If you look at any of my high-energy weapon large starship designs (I don't
think the dropship counts), you'll find a note about how much power is required
in combat versus how much is required in "running mode". *I* usually calculate
the running power as full maneuver power plus full life support power. If you
wanted to run your ship at the absolute minimum power, I'd call it the amount
needed for full life support power, most of the time...but even that could
be reduced if you were willing to cut the grav plates (you wouldn't need
inertial compensators if you weren't accelerating). Unless you precalculate
these things in the design phase, or maintain your complete design sheets,
figuring these things out on the fly will be annoying.
Does anyone else have thoughts on how much power you really require in jump
space? Do you need the inertial compensators? Any maneuver power?? I would
not think so.
Rob