Howdy!

On Mon, Sep 15, 2014 at 7:01 PM, Bruce Johnson
<xxxxxx@pharmacy.arizona.edu> wrote:
>
> On Sep 15, 2014, at 3:36 PM, Cheng Tseng <xxxxxx@kennett.net> wrote:
>
>> ObTrva: I am still confused over how Traveller gets the displacement tons from the mass and vice versa, for a ship design.  I always thought that going to a pure mass system (A la David Weber's Honor Harrington.) might be less confusing.
>
> It might be, but since jump drive is volume-dependent, not mass-dependent it makes sense to size ships in volume. Why it isn’t in cubic meters is probably due to some un-nammed naval traditionalist during the Rule of Man shoehorning the term into use.
>
Even today, ships' tonnage is a volume, not a mass measurement. In some cases
(Gross Tonnage), the conversion to cubic meters or the like has a
factor that varies
as the size of the vessel.

A measurement ton, or freight ton is another volumetric measure, being
40 cubic feet.

So, it makes perfect sense for ship tonnages to be volumetric rather
than mass based.

Traveller simply introduced a different unit whose definition varied
from version to
version, and that variation is unremarkable compared to earth's history.

Heck, "ton" comes from "tun", or a specific sized cask of wine, etc.

yours,
Michael

--
Michael Houghton   | Herveus d'Ormonde
xxxxxx@gmail.com         | White Wolf and the Phoenix
Lanham, MD, USA            | Tablet and Inkle bands, and other stuff
                          | http://whitewolfandphoenix.com