GPS and traditional navigation

[rwthomas1]

I would like to thank everyone for their input. The thread was informative and provided some unique views on GPS and navigation. Ultimately I would like to have a GPS/chartplotter and radar at the helm, a second unit repeating that info at the nav station, be it a repeater or a laptop. Lastly a backup GPS handheld would round out the nav gear. I view this stuff as required if venturing beyond the bay. Sure, we could go without it as many before us have, but if its available and relatively inexpense compared to a mishap from not having it then why not? I just need to pull in a few extra contracting jobs to cover it all....
RT

 

[therapidone]

Caveat Nautor!

Info about charts posted to a listserv to which I belong...

Regards,

Ed
==========================================================
Sailor beware!

We had brand new charts in St. Vincent and the Grenadines. The survey date just said "18th Century". Those guys were great. Imagine trying to toss a lead weighted line thousands of times while checking bearings with a hand held compass. Of course you started with a hand held sextant to fix your latitude and triangulated your way from island to island.
========================================================
Grant Woodside <gexxx@xxxxx.com> wrote:
The next time you use your paper or electronic nautical chart you may
not trust the data so much.

I knew that the survey for chart data was not recent. I thought the
survey was performed in the early 1970s. Was I suprised when I viewed
the current 12270 chart print-on-demand chart and found the survey was
performed 1900-1939!! I don't know if this is on the current
pre-printed chart, but it is on the current print-on-demand chart.

See for yourself.
Go to http://nauticalcharts.noaa.gov/
Click on the chart next to "Raster Navigational Charts"
Scroll down and click on "Free "Demo" Raster Chart Navigation Software"
Scroll down and click on "NOAA Raster Chart Viewer"

You are here http://www.nauticalcharts.gov/viewer/
Scroll down and click on "NOAA's On-Line Chart Viewer"
Click "Atlantic Coast"
Scroll down and click on "12270"

I sent you the long way to show you how much data is available.

On the chart on the right, you see a legend box in the lower right
corner. Click on it a couple of times to zoom in. Use the arrow keys to
move it around.

South River, West and Rhode Rivers are source B4. You see that B4 was
surveyed 1900-1939. The Severn River, section B3, is much more recent,
1940-1969. This is closer to the 1970 that I previously understood. But
some of that data is 1940 or 1900!

Your GPS is very accurate to a few meters. How accurate were the
surveyors in 1900 or 1940 or even 1970? Remeber the chart on your GPS
was created with this ancient data.

Beware,
Grant