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**Wotname** · 14-10-2010, 06:05

I use a paper chart for situational awareness and a GPS to provide lat /long fixes.

For route planning I use paper and transfer the waypoints into the GPS and then use the GPS & paper 50/50.

Of course I don't own a chartplotter and my GPS does not support e charts - maybe I need to upgrade but so far this system works for me.

Not sure where I fit on Ex-C's poll

**Dockhead** · 14-10-2010, 07:01

Quote:

Originally Posted by Bash

that's an interesting argument.

I find that the one area where paper charts are more valuable than chartplotters is in planning a voyage prior to departure. . . . In essence the GPS is better at letting me know where I am, but the paper charts are better at letting me decide where I want to go.

+1

Exactly. I may be repeating myself, but there is no way to properly plan a voyage with chart plotters the way they work today. That is because when you zoom out to see the whole route, the detail disappears. You just cannot get the whole integral picture of your voyage with a chart plotter. That is because your chart plotter does not have the instantaneous zoom, nor the peripheral vision, of your own eyeball looking at a paper chart in your hand. These are powerful functions not replicated by electronics (so far).

I am not a technophobe and in fact I love my electronics, but I find over and over again that if I skip the chart study prior to a voyage, especially in unfamiliar waters, and try to conduct the voyage with chart plotter alone, I arrive disoriented. Disoriented = dangerous.

Chart work is an integral part of good seamanship!

**boatman61** · 14-10-2010, 07:31

Is it just me or is there actually a trend on here to make a fairly simple process (Navigation) seem overly complicated...
or is it just mankinds inbuilt laziness pushing him towards letting something else do all his thinking for him....
Then its never 'His Fault'

My distrust of GPS etc goes back to 96 when the GPS said we were in the Dragonera Channel when my eyeballs said we were in fact entering Soller....
Who knows when or why these things happen but they do... blind faith is not my strong suit... and CP's are like God's...
Contradictory, prone to lie or let you down...lol

osirissail · 14-10-2010, 08:08

"My distrust of GPS etc goes back to 96 when the GPS said we were in the Dragonera Channel when my eyeballs said we were in fact entering Soller...."
- - Actually I would suggest that is backwards, the GPS told you your real position on the planet, but the charts were not registered (offset error) correctly so it appeared on the chart that you were someplace else. This is extremely common even today.
- - Most governments are broke and allocating money to correct and update charts is very low on their priority list. Private companies can do this but need to actually visit many locations covered by a particular map to determine what the "offset" is between reality and what is depicted on the chart by Lat/Long's. However, if a private company "messes" with a government chart the legal liability for damages by somebody using that charts shifts from the government to the private person/corporation/etc. The few "private" chart makers are located in places where you cannot sue them for your own stupidity. But these places are rare and far between.
- - Determining the "offset" between you GPS Lat/Lon's and what the little "boat symbol" superimposed on the electronic map is a very important safety factor these days. As others have mentioned it is common for the little "boat" symbol to be tracking through a mountain while you are obvious in the middle of a bay or traversing a coastline.
- - Visual fixes, as described by others, is probably one of the best ways, but another is to manually put your Plotter/ENav computer program's cursor on the spot on the e-chart where you know you are from visual observations. Then read off the distance and direction between the cursor and the little "boat" symbol. I do this frequently when entering harbors and can remember that in this place my real position is "xx" nm/yards/meters to the left/right/forward/behind the little boat symbol.
- - The human brain is normally quite good at spacial re-orientation if you are paying attention to where you are going - versus watching those topless French young ladies sunning on the catamaran off to your side.

captainKJ · 14-10-2010, 08:22

"My distrust of GPS etc goes back to 96 when the GPS said we were in the Dragonera Channel when my eyeballs said we were in fact entering Soller...."

GPS was VERY inaccurate many years ago,,, military error correction, and the fact that there were not as many satellites then as there are now. with DGPS in play GPS is more accurate than ever,,,,,,,

Actually I would suggest that is backwards, the GPS told you your real position on the planet, but the charts were not registered (offset error) correctly so it appeared on the chart that you were someplace else. This is extremely common even today.

this is NOT backwards,,,,, GPS is more accurate now more than ever. DGPS uses ground relays and orbiting satellites to get an more accurate position.

in the early 80 and 90 GPS was VERY inaccurate but not so today

a military signal error was put into the satellites to make the GPS less accurate for military reasons,,, President Clinton had them take this out,,,,this error can be reintroduced in a time of war,,,

**boatman61** · 14-10-2010, 08:29

Quote:

Originally Posted by osirissail

"My distrust of GPS etc goes back to 96 when the GPS said we were in the Dragonera Channel when my eyeballs said we were in fact entering Soller...."
- - Actually I would suggest that is backwards, the GPS told you your real position on the planet, but the charts were not registered (offset error) correctly so it appeared on the chart that you were someplace else. This is extremely common even today.
- - Most governments are broke and allocating money to correct and update charts is very low on their priority list. Private companies can do this but need to actually visit many locations covered by a particular map to determine what the "offset" is between reality and what is depicted on the chart by Lat/Long's. However, if a private company "messes" with a government chart the legal liability for damages by somebody using that charts shifts from the government to the private person/corporation/etc. The few "private" chart makers are located in places where you cannot sue them for your own stupidity. But these places are rare and far between.
- - Determining the "offset" between you GPS Lat/Lon's and what the little "boat symbol" superimposed on the electronic map is a very important safety factor these days. As others have mentioned it is common for the little "boat" symbol to be tracking through a mountain while you are obvious in the middle of a bay or traversing a coastline.
- - Visual fixes, as described by others, is probably one of the best ways, but another is to manually put your Plotter/ENav computer program's cursor on the spot on the e-chart where you know you are from visual observations. Then read off the distance and direction between the cursor and the little "boat" symbol. I do this frequently when entering harbors and can remember that in this place my real position is "xx" nm/yards/meters to the left/right/forward/behind the little boat symbol.
- - The human brain is normally quite good at spacial re-orientation if you are paying attention to where you are going - versus watching those topless French young ladies sunning on the catamaran off to your side.

Sorry Orriss.... it was the GPS that was out.... we had some non-sailing friends on board and I was demo'ing how to integrate GPS info onto the chart... the plotted GPS position was Dragonera... triple checked.... the actual position was Soller... Admiralty Charts of Mallorca are pretty accurate I think you'll find...
But I guess you've gotta defend your corner

osirissail · 14-10-2010, 08:45

Nominal GPS accuracy when the civilian units became available back in Gulf War I was 15 meters (49 feet)l. My boat is bigger than that. The military had the ability to dither the signal to induce errors up to 300 meters. With the advent of the huge civilian use and reliance on GPS the military's arbitrary ability to dither GPS was prohibited by Pres. Clinton.
- - Depending upon the year, make and model of the GPS you were using there are many reasons for large errors. The largest error was 104nm discovered by an around the world rally that left Indonesia and was sailing for the Red Sea. It was discovered after all the boat joined up at a common GPS position prior to the entrance that the nautical chart they were using was an old French chart. The lat/long's used off the chart for the meeting point were based on the original zero meridian being in Paris, not Greenwich.
- - In the early model GPS units you had to manually insert the correct map datum as WGS84 standards were not agreed to yet. This led to large, even enormous differences between GPS Lat/long's and chart Lat/longs. There was nothing wrong with the GPS's, the users did not properly calibrate their systems to match the charts. It is very easy to blame a machine rather than the user for not using it correctly. And this goes on even today and most assuredly will continue into the future. After all, "computers can't lie . . ." "GIGO"
- - How you use the equipment makes all the difference between accurately and safely knowing where you are or blaming the "machine" because you ran aground or into a charted reef.

captainKJ · 14-10-2010, 08:46

Admiralty Charts are by far more superior than the charts we use it the united states,,, that is changing with several private companies undercontract with the U.S.Government to do chart surveys,,, a friend of mine just completed a 3 month contract working of the coast of florida for a just such a company

MarkJ · 14-10-2010, 09:43

Quote:

Originally Posted by Ex-Calif

(PS - I am totally in Mark's camp now that he is not an idiot and almost a circumnavigator - no paper for me...)

Thanks Dan. I'm not 'nearly' a circumnavigator... I'm already one! Having crossed my 'outbound' track 7 months ago. But Sea Life with me aboard is just about to finish her first one

Basically now I have done 1.5

BTW I've checked out of this thread...

highseas · 14-10-2010, 10:04

Anytime I am less than 5 miles from land I would be looking at other indicators as to my position, as well as my GPS. I feel quite comfortable trusting my plotter the rest of the time.I study my routes intensely on paper,google earth and plotter, before the anchor is up.

SaucySailoress · 14-10-2010, 11:13

We went aground once in our dive boat (fortunately no pleasure divers aboard - it was a commercial job in a remote location up near Iraq). Marc programmed the course into the GPS, the Dive Master was driving. Marc had missed a waypoint. At the time, I was saying something like "shouldn't that red buoy be green if it's to port?" and Marc replied "What red buoy?" and then we grounded. At speed.

No damage, fortunately; but we learnt from the experience. That was, doubtlessly, human error. Now, we double check our course and waypoints as we would with paper charts.

**hummingway** · 14-10-2010, 11:41

I find the Canadian charts are very accurate and they show anchorages with good holding very clearly. Which, as Bash pointed out, makes paper very nice for planning.

**Ex-Calif** · 14-10-2010, 11:52

Let's get over the GPS is inaccurate paradigm as quickly as possible.

GPS is now used in precision approaches for aircraft providing both lateral and vertical guidance to something like 300 feet.

If there is a problem on the boat it is going to be related to how the chart system is implementing with the gps.

GPS is accurate...

osirissail · 14-10-2010, 18:50

Quote:

Originally Posted by Ex-Calif

Let's get over the GPS is inaccurate paradigm as quickly as possible.
GPS is now used in precision approaches for aircraft providing both lateral and vertical guidance to something like 300 feet.
If there is a problem on the boat it is going to be related to how the chart system is implementing with the gps.
GPS is accurate...

- - Actually, the situation is even worse - here is one of a number of graphs from a study of Differetial and WAAS compliant GPS's. One of which is the Garmin 76 series which I have accumulated 3 of . . .
GPS WAAS ACCURACY

- - Differential/WAAS compliant GPS systems are currently accurate to about 2 meters (6.6 ft) with the mean being 1.5 meters (5 ft). You can literally take GPS locations of stuff in your boat (while in a boatyard on jackstands) and use the GPS to find the stuff again. (A little hyperbole there but you get the idea).
- - Problem is our nautical maps and charts are no where near that accurate and sometimes way off resulting in that famous "sailing through the mountain" presentation on the computer/plotter screen.
- - However, there is a bright side - recorded "Tracks" - If you set your nav system to record your track as you go from place to place you can very accurately "retrace" your "footpath" back again. Of course, this presumes you did not hit anything the first time. I collect and trade "track records with other cruisers and although the map presentation is sometimes off, the tracks are dead on. Unless the guy lied and did hit something and didn't tell you. Which is why you never trust anything no matter what the accuracy until you have done it personally yourself.
- - I have an extensive library of RNC charts - about 14,000 covering almost the whole world. My paper chart collection - about 10 inches thick consisting of about 200 to 300 charts in a locker. Unfortunately over the decades the paper charts are drying out and crumbling - except for the "waterproof chart" versions. I like those. I still buy paper/plastic charts from offshore chart makers because the main library of the world's RNC and ENC charts is rather incomplete especially in certain out of the way gunkholes and hidden harbors. With Fugawi I can scan these "odd-ball" charts and register them for use on my PC computer navigation system. I think you can do the same thing with the OpenCPN system. This fills in the gaps where government charts are non-existent.