Try not to talk down to someone that has spent time in cartography Jeff.
With an expected accuracy of 50 feet max... a GPS is accurate enough but not
pin point. I believe I stated it should be used in conjunction with a chart
and not as a stand alone based on waypoint data not verified to the chart
datum. If you have a chart whose GPS Data puts you aground by 100 feet...
you are either using errata datum or your chart is ****ed. Do you have any
comprehension of the sphere labeled as "sea level" and the fact it's
actually a not actually perfectly spherical?
You want to really converse on the specifics of GPS with someone that has
utilized it for data triangulation. I have targeted data over a 48 hour
period based on surveyed benchmarks that clearly illustrates the accuracy
expected at differing latitudes and altitudes. It looks like a shot gun
pattern at 20 meters.[s/a off] I can still give you the error ratio for your
chart with 3 separate fixes confirmed and verified by alternate sources.
A correctly configured GPS is a great tool...... when used by knowledgeable
people and proper charts.
CM
You can rely on a GPS to provide very usable data once you ascertain it's
accuracy on a chart by comparative data. Once that is established... you
should be well aware of your coordinates
"Jeff Morris" jeffmo@NoSpam-sv-lokiDOTcom wrote in message
...
| Its not that the ICW is poorly charted, its that the chart only has to be
off by 100 feet
| to put you on land. Its possible that the last time through SA was turned
on for a while,
| but I really had the feeling that several of the charts I was using was
simply displaced
| by 100 feet of so. So how often do you think the creeks in Georgia get
re-surveyed?
|
| For an article on the errors in Bimini, see:
|
http://www.bluewaterweb.com/news/9-01gps.htm
|
| Your comments are inconsistent - first you say GPS "should never be relied
on as sole
| source" but you claim that you don't agree with "You should not rely on a
GPS when using a
| chart."
|
| Seems to me that you just like to argue and you don't care whether you
make any sense. At
| least Neal sticks to one position, albeit usually wrong.
|
|
| --
| -jeff
| "Constant Vigilance!" - Frances W. Wright
|
| "Capt. Mooron" wrote in message
| ...
| First off it's difficult to believe that any stretches of the ICW are
poorly
| charted. I'm not a big proponent of GPS accuracy... I do concur with
Jon's
| assertion that it's a tool... it has it's limits and should never be
relied
| on as sole source for navigation. That being said... I've seen
supposedly
| competent sailors use default datum or operate in 3D fix modes. What I
don't
| agree with is ...
|
| A]- "You should not rely on a GPS when using a chart"
| That position would have you question your radar, sonar, chronograph and
| compasses.. never mind the plotting tools!
|
| B]- "It tells you nothing about your actual position relative to actual
| obstructions"
|
| It does indeed confirm a fix if you have a chart..... so does radar.
|
| C]- "Charts are notoriously inaccurate and don't match long/lat info
|
| P-l-l-u-u-u-u-e-e-e-e-z-z-z-z-e-e-e...... they certainly are Not!.
| Especially if
| you can read one, verify fixes and have the latest datum.
|
| CM
|
|
|
|
|
|
| "Jeff Morris" jeffmo@NoSpam-sv-lokiDOTcom wrote in message
| ...
| | Jon has a point. There are certain locations that are notoriously
poorly
| charted,
| | datum-wise. The ChartKit I have for the Bahamas is way off. I also
| found that for long
| | stretches of the ICW, my charted position was on dry land.
| |
| | For most of where I sail, however, the GPS and the chart agree to a
boat
| length or better.
| |
| |
| | "Capt. Mooron" wrote in message
| | ...
| | Were did you dig up this crap Jon??? Learn how to enter correct
datum
| and
| | save yourself further embarrassment.
| |
| | It's a good thing both you and Neal sail in protected waters with
line
| of
| | sight navigation or there would be a lot less boats around.
| |
| | CM
| |
| | "Jonathan Ganz" wrote in message
| | ...
| | | You should not rely on a GPS when using a chart. It's a tool
| | | only. It tells you nothing about your actual position relative to
| | | actual obstructions. Charts are notoriously inaccurate and
| | | don't match long/lat info.
| | |
| | | "Simple Simon" wrote in message
| | | ...
| | | And, good morning to you, sir!
| | |
| | | With the advent of GPS and its accurate nature, plotting your
| | | position on a chart is a more accurate method than using
| | | depth readings and dead reckoning. It's that simple.
| | |
| | | S.Simon
| | |
| | |
| | | "Thom Stewart" wrote in message
| | | ...
| | | Good Morning Simple,
| | |
| | | Many of us SAILORS that sail among Whales use charts and depth
| finders
| | | to get a location of exactly where we are on the chart. This
is an
| | | accepted practest in DED piloting.
| | |
| | | We finally got a nice cleaning rain last night and we have
about
| 5mph
| | | wind at the house here. Waiting for my dog to wake up. We'll
| | probabilly
| | | spend the day out on the water. The Pilothouse will come into
| play.
| | Nice
| | | and dry and warm.
| | |
| | | OT
| | |
| | |
| | |
| | |
| | |
| |
| |
| |
| |
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