No Water Present

One of the nagging issues with my map was what color to use for the worlds.

The classic Spinward Marches map uses blue for "water present" and white for "no water present." At first I'd assumed that "no water present" simply meant Hydrographics=0. But comparing this output to maps of the Regina subsector didn't produce the right results - there were many more "no water present" worlds.

I asked on the TML and did some poking around, to no avail - the Atmosphere code had some effect, but it wasn't obvious or documented, so I added it to my "TODO" list. Looking at TD #6's map of the Shuna subsector of Lishun I was inspired to check the rules again - Book 3 and MegaTraveller Referee's Handbook. And there it was.

So, for reference, water is present if:

• Hydrographics > 0 (duh)


• Atmosphere > 1 (else, ice capped)


• Atmosphere < A (else, exotic, so a fluid hydrosphere if Hydro > 0)

That seems to work.

Ω