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Capt. JG

wrote in message
...
On Wed, 16 Apr 2008 11:55:30 +1000, Herodotus
wrote:

On Tue, 15 Apr 2008 17:41:29 -0400, wrote:

On Tue, 15 Apr 2008 16:50:07 -0400, "Roger Long"
wrote:

"Wayne.B" wrote

There is really no excuse for not carrying a spare hand held or two
and a few extra batteries. I use them in the dinghy at times.

I do but that's not what I was talking about. Someday, the airforce is
going to detect an unidentifiable radar target and turn the whole system
off
just in case it is a poor mans GPS guided missile. This is one reason
why
the Russians have their own system and the European Union wants to set
up a
third. Like the Internet, GPS was originally supposed to be just one of
the
toys the taxpayers buy the Pentagon they can turn it off any time they
want.

There are also solar flares and other potential disruptions.

There was a time when turning the system off might have been an option,
but
theses days GPS is used for too many other things, both public and
private. They
really don't have the option any longer.

I don't think it's any more likely then the government shutting down the
Northeast electrical grid to try and thwart a terrorist attack.

Regardless of whether or not "they" turn of the GPS system, there is
the ever present possibility of receiving a direct hit from lightning
as I have, taking out virtually all my instruments, SSB radio and LCD
monitor with the exception, strangely enough of the laptops.
Electrmagnetic induction can even fry the spare GPS unit in its box
unless of course you have sufficient warning and put all in the ss
oven which would act as a a Fraday cage.

This is why I carry and keep in good order my trusty old sextant.

Peter

Charts can get blown overboard. You can break or bend a sextant by
accidentally sitting on it or dropping it. Every method of navigation
is vulnerable in mulitiple ways. Don't overlook plain old user error,
either. That's a very common failure for most navigation methods.

If you are relying on any single form of navigation, you are at
greater risk.

Correct... absolutely. Thus, we shouldn't rely on one method of navigation.
Multiple methods and backups are the way to go. Bring the sextant and 1/2
dozen GPS - they're cheap.

--
"j" ganz @@
www.sailnow.com