Re: [gurps] [VEHICLE] of the week 707 – Kargash-class 100-ton Patrol Schooner

[David Scheidt]

On Mon, May 12, 2008 at 8:15 AM, Onno Meyer <Onno.Meyer at gmx.de> wrote:
> > If you include two sets of navigation instruments, standard practice
>  > is to have three.  That lets you discard the result of the one that's
>  > gone wonky.
>
>  Or four, to take one off-line for scheduled maintenance while three still
>  provide redundancy. But this is a TL5 sailing ship, and I figured that it
>  is good enough to _know_ something is wrong. The critical thing would be
>  to loose the accurate time - if a sextant or map set is "broken", that
>  should be easy to tell. They'd have to use their nautical judgement on
>  choosing the right clock, or cannibalize a lifeboat (pinnace) kit.
>

At TL5 it's the clock that's the precision instrument that's prone to
failure.   Everything else is either simple -- like charts, tide
tables, and log-trig tables-- and not subject to break down (loss or
damage, yes, but a map never stops working), or it's something that
can be improvised -- lead lines, the log used for measuring speed, and
sextants.  The clocks are the only thing that's subject to breakdown
and worries about accuracy. You leave them set to a standard time.
(On earth, it was London time, for most people, but it doesn't really
matter, as long as you know the longitude of the point whose time
you're keeping.).  The difference between local noon and home's noon
tells you your longitude.  If you've only got two clocks, and they
start drifting apart, you can't tell which is right.  With three, you
can discard the one that's whacko, and average the other two.  Also,
if they've got any off-planet trade, they'd surely import good time
keeping devices: the cheap digital watch you can buy at the gas
station for $3.99 keeps better time and is more reliable than anything
that can be done at TL5.  A calculator would also make navigation
easier and more accurate.  (I'd bet I could design a combined device
that would have a volume (10K + units) price of about $15 in 2008. )

-- 
David Scheidt
dmscheidt at gmail.com