Hi Rupert,

> On 10/11/2020 12:10 AM Rupert Boleyn <xxxxxx@gmail.com> wrote:
>
>
> On 11Oct2020 1945, xxxxxx@gmail.com wrote:
> > Water can't be *much* more compact than LH2 drawn from said water.
> > You're losing a crap lot of weight from the O2. I suppose it is
> > possible that H20(l) can be more compact than H2(l) .
> One tonne of liquid hydrogen takes up forteen cubic metres of volume.
> Nine tonnes of water include one tonne of hydrogen, and has a volume of
> nine cubic metres. You get about 1.55 times as much hydrogen into the
> same volume, but the mass per quantity of hydrogen is nine times as
> great. In CT, MgT and a number of other rule sets spaceships care about
> volume, not mass, so water is useful if the referee is willing to go
> with it. The downside is that it's very definitely unrefined fuel, even
> if the ref is generous (I simply disallow using water as jump fuel), and
> carrying it and then refining it requires a refinery/purifier, time, and
> a tank to hold the water as well as one to hold fuel.
>
Do you allow the use of the gases skimmed from a gas giant as unrefined jump fuel?

Do you allow the use of melting icy comets down as unrefined jump fuel?

Unrefined jump fuel has consequences per the Traveller rules. I recall, but as usual, I can not find the text that indicates how long it takes to convert the unrefined fuel in water into refined fuel.

Tom Rux