Chuck Gould wrote:

Now that 99% of boats in which any formal navigation occurs depend
heavily on GPS, paper charts are becoming pretty scarce. Sure, we all
keep nodding and agreeing whenever anybody reminds us to have paper
charts aboard for a backup- but pretty soon it begins to sound like
"Make sure you wear your PFD"- advice that most will agree is sound
but far fewer follow in practice.

In the news this morning, China launched a missle that flew into space
and destroyed a (Chinese) satellite. Omnious.

In any confrontation where a higher-tech country invaded a lower-tech
country, taking out the GPS system would give the defenders, more
familiar with the geography and terrain, some serious advantages. I
believe that taking out the GPS system would interfere with the
function of many of our "smart" weapons, drones, etc. Eliminating the
high tech advantages would reduce the conflict closer to a point where
the country with the greatest number of people in the army had a better
chance of winning. (oops)

Yeah, only 6 orbits, well under geosynch so 6 rockets with a payload of
small needles or ball bearings could take the lot down. Any country
with its own ICBMs could do it with no real difficulty, but it would be
an act of war so unless the US is still feeling feisty, we are *fairly*
safe


So let's be careful to maintain peaceful relations with China. If we
grump 'em off too badly, our GPS system will be an early casualty.

People who laugh at me for keeping a paper chart on the chart table
immediately below my Simrad plotter will be asking me to loan them a
chart or two if we get tangled up with the Chinese. :-)

A working Loran receiver would be worth having as backup, and a plotter
that uses an *EXTERNAL* NMEA0183 input for the GPS would be nice.

We dont run a screen based plotter on our yacht. A Yeoman plotter
http://www.yeomanuk.co.uk/
is much better at surviving the rather rugged conditions on board even
at the chart table and lets me continue to work on paper charts.

A cockpit repeater and a pre-programmed 'string' of Yeoman derived
waypoints give *most* of the advantages of a coachroof mounted plotter,
and for close in stuff, a chart in a waterproof sleeve with the intended
route drawn in and a couple of critical waypoints to *AVOID* make up for
the rest.

The Yeoman *can* be dropped back to dead reckoning mode and accepts
course, speed, set and drift. The DR position is maintained concurrently
with the GPS fix so if used, it guards against GPS 'spoofing'.

Thanks, Chuck, for the advisory. I'll make sure I have a laminated copy
of the Yeoman DR instructions onboard next season and if going further
than a coastal hop will put the sextant, a current astro almanac extract
and condensed tables onboard as well. I could use the practice.

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
[at]=@, [dash]=- & [dot]=. *Warning* HTML & 32K emails -- NUL:
'Stingo' Albacore #1554 - 15' Early 60's, Uffa Fox designed,
All varnished hot moulded wooden racing dinghy.