Andy K. wrote:

snip

The errors that were found involve markers in the channel leading through
the bayou where I work. it is possible that the markers were replaced after
hurricane Opal in '95. We don't use the chart chips to navigate because we
have extensive knowledge of the local waters and can run using visual cues
or radar.

I have never checked the marker positions against those on the current
charts and would not be surprised if they were off.

Chart plotters and chips are fine, but we never use them as a primary means
of navigating any boat we crew. Our captains will use a combination Nobeltec
software along with paper charts during most trips.

I'm not out to slam Garmin or anyone else as I have a bunch of their
equipment installed on our boats and boats belonging to our customers. All I
can say is don't let the electronics do all the thinking for you.

Then I'd say the kind of errors you found are common. I helped bring a
boat up the ICW from Florida this spring and we had the newest Navionics
chart chips and new MapTech chart books and there many times when
disagreements were noted between the electronic and paper data and the
real world.

In a couple of instances the GPS lat/long readout or a visible and
obvious local feature is what nailed down the the fact that the charting
was wrong. Once or twice we ran a string of day marks that had been
re-numbered but that not was on reflected in the charts yet.

And, like you, I don't really expect it all to be right on the money
anyway. My feeling is if you have two or three sources of data
available to localize yourself with, you're asking for trouble if you're
not using most of them most of the time. I really enjoy playing the
coastal navigation game and keeping my head in it. People that say
bringing a boat up the ICW is boring are probably not paying enough
attention to what is going on.

I really liked having the chart plotter showing two magenta lines that
depicted the original location of the dredged channel. There were some
areas where you could watch the bottom start coming up from the ambient
depth and you could usually count on being right if you eased boat back
towards the original centerline. There was a lot of times where just
eyeballing it would not have put you in the right place.

The owner of the boat thought he could eyeball it from the flybridge
with no navaids and a broken fathometer readout and he frequently
polished the screws in the silt. Sometimes we'd be at the primary helm
station watching the plotter and sounder as he drifted out of the
channel and we'd tell him where the channel was and which way to go to
get back in it and he'd want to argue about it.

We finally just started letting him nibble at the mud and run it aground
as much as he wanted, it was his boat.

Jack

--
Jack Erbes in Ellsworth, Maine, USA - jacker at midmaine dot com

"Jack Erbes" wrote in message
...
Andy K. wrote:

snip

The errors that were found involve markers in the channel leading
through
the bayou where I work. it is possible that the markers were replaced
after
hurricane Opal in '95. We don't use the chart chips to navigate because
we
have extensive knowledge of the local waters and can run using visual
cues
or radar.

I have never checked the marker positions against those on the current
charts and would not be surprised if they were off.

Chart plotters and chips are fine, but we never use them as a primary
means
of navigating any boat we crew. Our captains will use a combination
Nobeltec
software along with paper charts during most trips.

I'm not out to slam Garmin or anyone else as I have a bunch of their
equipment installed on our boats and boats belonging to our customers.
All I
can say is don't let the electronics do all the thinking for you.

Then I'd say the kind of errors you found are common. I helped bring a
boat up the ICW from Florida this spring and we had the newest Navionics
chart chips and new MapTech chart books and there many times when
disagreements were noted between the electronic and paper data and the
real world.

In a couple of instances the GPS lat/long readout or a visible and
obvious local feature is what nailed down the the fact that the charting
was wrong. Once or twice we ran a string of day marks that had been
re-numbered but that not was on reflected in the charts yet.

And, like you, I don't really expect it all to be right on the money
anyway. My feeling is if you have two or three sources of data
available to localize yourself with, you're asking for trouble if you're
not using most of them most of the time. I really enjoy playing the
coastal navigation game and keeping my head in it. People that say
bringing a boat up the ICW is boring are probably not paying enough
attention to what is going on.

I really liked having the chart plotter showing two magenta lines that
depicted the original location of the dredged channel. There were some
areas where you could watch the bottom start coming up from the ambient
depth and you could usually count on being right if you eased boat back
towards the original centerline. There was a lot of times where just
eyeballing it would not have put you in the right place.

The owner of the boat thought he could eyeball it from the flybridge
with no navaids and a broken fathometer readout and he frequently
polished the screws in the silt. Sometimes we'd be at the primary helm
station watching the plotter and sounder as he drifted out of the
channel and we'd tell him where the channel was and which way to go to
get back in it and he'd want to argue about it.

We finally just started letting him nibble at the mud and run it aground
as much as he wanted, it was his boat.

Jack

--
Jack Erbes in Ellsworth, Maine, USA - jacker at midmaine dot com

I think the biggest problem with all the new electronics is the faith put in
them buy unsalted owners. At times we have new people on the boats that will
lay out a GPS course and go. Then we have to remind them to look outside the
boat as they are making their way from waypoint to waypoint.

I recently made a run in the ditch between Panama City Fl. and Pensacola
using waypoints hand plotted by one of the captains. Out of all his plots he
had only 2 that were fuzzy, but they were caught when we made the run. The
nav software on the laptop in the pilot house was good, but also not 100%.

We have a boat making the same run today and I'm keen to see how it turns
out as the second captain is using the nav software to pull his waypoints.

snip

I think the biggest problem with all the new electronics is the faith put in
them buy unsalted owners. At times we have new people on the boats that will
lay out a GPS course and go. Then we have to remind them to look outside the
boat as they are making their way from waypoint to waypoint.



It's the mental set of the new boaters. They have been told how
wonderful the electronics are and they never question them or their
performance. It's this "blind faith" that leads to trouble.

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."
Mark E. Williams

Maynard G. Krebbs wrote:

snip

I think the biggest problem with all the new electronics is the faith put in
them buy unsalted owners. At times we have new people on the boats that will
lay out a GPS course and go. Then we have to remind them to look outside the
boat as they are making their way from waypoint to waypoint.




It's the mental set of the new boaters. They have been told how
wonderful the electronics are and they never question them or their
performance. It's this "blind faith" that leads to trouble.

In all fairness to the makers of the electronics, they do warn people
about the inherent problems during startup and the like but people
generally don't read that or remember it. There are similar warnings on
charts too.

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?

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.

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?

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. :)

--
Jack Erbes in Ellsworth, Maine, USA - jacker at midmaine dot com

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. :)

--
Jack Erbes in Ellsworth, Maine, USA - jacker at midmaine dot com

The R/V that I ride carries an A3 comm consol along with a SART and 406
EPIRB. You can hit 3 red buttons and grab the SART out of it's rack outside
the pilot house on your way to the lifeboat. The captains are constantly
working on upgrading their licenses and the company helps foot the bill for
training (this includes celestial navigation, bridge management, basic
Radar, ARPA and other). Overall, I feel very safe while working on the
boat. It's the thought of those that have no clue that bother me.

Just in the last year, in our area, we have had a large boat crash into the
jetties, one into a dredge pipe and another aground. No good excuse for the
jetty thing, the pipe guy claimed he never saw the yellow strobes and the
grounding guy was running on his GPS course.

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