> On 12 Jun 2014, at 03:05, Derek Wildstar <xxxxxx@prismnet.com> wrote:
>
>> On Jun 9, 2014, at 4:19 PM, Timothy Collinson <xxxxxx@port.ac.uk> wrote:
>> I'm using the rule of thumb that says deck plans should have twice the number of squares of the tonnage.
>
> That’s basically correct.  A standard deck square is 1.5 meters square and 3 meters tall:
> 1.5m x 1.5m x 3m = 6.75m^3.  Two squares is therefore 13.5 cubic meters.
>
> The Traveller volume standard is a ton of liquid hydrogen; the density varies with temperature, but is typically between 70.85 and 71.00 kg/m3.  That works out to just over 14 cubic meters per ton (14.08 to 14.11).  Slush hydrogen has a density of about 85 kg/m3, which would put a ton at 11.76 cubic meters.
>
> Slush hydrogen is a mixture of solid, liquid, and gas at the triple point.  For hydrogen, this is a lower temperature and higher density than liquid hydrogen - about 14K (-259C) and and 7 kPa (about 1 PSI, or about 1/14th of an atmosphere).
>
> IMTU, I figure that typical Traveller starships aim to keep their fuel as slush hydrogen at the triple point, and provide about 15% extra space in the tankage to accommodate chillers and to contain temperature excursions.
>
>> So a 400-ton ship would have 800 one point five metre squares.
>
> Yep.
>
>> So if I have four decks of 200 squares and a fuel deck (not shown on the plans) as well.  That's NOT a 400 ton ship but a 500 ton ship, right?
>
> Right.  A 400-ton J-1 ship will need 40 tons (or 80 squares) of fuel.
>

Excellent.  Thank you for that.

I think I'm going to have to admit that my "2000-ton" ship is actually
a 3000-ton ship.  (I had another count of squares last night and found
some more fuel tanks in the side view that I'd forgotten about in the
plan view.). Or remove some squares.  Except of course that the space
is all utilised. :-(

I'd be happy enough to just say it's a 3000-ton ship except that that
means I can't design it under T5 which only goes up to 2400-tons,
saying that this covers Adventure Class Ships and anything bigger is a
Battle Class Ship (but has no rules for - I assume they're coming).

I did double check that I had the fuel requirements right.  Jump-4 and
12 weeks of operation I think I had as 1048 tons of fuel or so. So
that needs 2096 squares for fuel.  I think I had 1200 formally.  So
need another 800.  Of course now it's a 3000-ton ship, I shall have to
redo all the requirements anyway.  Which will of course then impact
the size and contents.  <sigh> It might be easier to start again.

Perhaps I should start with something I know like the Beowulf which
has known solutions.

tc