On 17Nov2019 1647, Thomas RUX wrote:

> In Phil's reply that was snipped he indicated that the Express Boat
> Network was J3 and then upgraded to J4. Going back over the earlier
> posts the only item I found that mention J4 was about the IN.
>
> Historically speaking the military usually gets the better toys. The
> Express Boat Network is part of the Imperial Interstellar Scout
> Service which is seconded to the IN during war, so I'm guessing that
> they probably would not have hulls that beat out the IN. The TL 15
> Fleet Couirer is equiped with a J6 drive while the Express Boat
> Network is still using J4.

The IN staying at J3 whilst the X-boats were J4 doesn't say that the IN
isn't getting better toys. The late 800s is when the Solomanis broke
away, so I think the upgrade to J4 was more about building a more mobile
fleet, and probably modernising it at the same time. It may have also
been the point at which the IN felt there were enough TL13-14 worlds in
their likely areas of operations that it was worth upgrading to J4
drives (and possibly TL14 overall). Most of their fleets are still J4,
even in the 1100s at TL15.

They started setting up the X-boat system in 624, after the Civil War
had ended. MT's Referee's Companion gives the following TL points for
the 3I:

Date  TL
-1776  10
  -650  11
  -150  12
  300  13
  700  14
  1000  15

I assume most of those dates are round numbers.

TL13 and Jump-4 is thus three centuries old at the time the X-boats were
introduced. I don't see any particular reason they'd not be put in using
the best available jump drives (high-priority couriers would still be
fast, using more direct routes).