On Thu, 23 Sep 2004 11:30:39 -0400, Jack Erbes
wrote:

The reason I want to use celestial offshore is to retain the
uncertanty in the back of my mind. That little ghost-voice saying,
"You're not really at that spot on the chart. You're somewhere around
that spot... maybe."

Great idea! I wonder, when you buy a sextant now does it have a warning
label on it somewhere too?

LOL, not sure if sextants have a warning label but they probably do.

Don't get me wrong, I think that GPS is great and wouldn't be without
one on a boat. Modern electronics are a boon to modern navigation.
They do however lead to a mind-set of unquestioning certanty. So use
them but don't put blind faith in them is all I'm saying.

I never got around to playing with sextants but if I owned a cruising
boat I'm sure I would have one on board and would play with it. And
then I would then look at a GPS to see how well I was doing with it.

There are a lot of uncertanties with celestial navigation. Small
bouncing boats don't make the best platforms for accurate sites. Then
there are math errors and errors looking in the tables.
These lead to a more cautious mind-set.

People (and not only beginners) tend to set too few waypoints without
checking the chart to see if there is anything to avoid hitting on
their intended track. LOL, even one of the Cruise Ships did this and
ended up running into the cliff side of a island.


Has anyone ever had a GPS that generated a apparently good fix that was
grossly inaccurate? A position that had a typically good EPE but was
just flat way wrong?

This was discussed not long ago in another of the boat groups. It was
said that there are dead spots around (North Carolina anyway ).

If I was going to equip a life boat I might give a modern, waterproof,
handheld GPS and some batteries higher consideration over a sextant. If
I had not been found or grounded by the time that quit working, the sun,
moon, and stars would be the backup. :)

A handheld VHF with plenty of waterproofed batteries might be more
valuable than a GPS because most liferafts can't really be steered.
Airliners and ships generaly can pick up your VHF.

Mark E. Williams