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Old 12-10-2010, 10:00   #151
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None including me ( and I have a hobby of trad nav methods), would run down charts. However what is a simple practical reason, (a) Cost and (b) Availability is what will doom paper charts. No doubt about it. Its simply too expensive to carry and maintain an extensive up to date paper chart portfolio. Its all right for weekend warriors sailng around the same area , to carry a few charts, but in my experience, circumnavigators and any long distance types arfe now relying on electronic charts more then anything else.

The arguments over, the users have spoken, the chart shops have gone ( from most major ports) . I for one mourn the passing of the paper chart , but I see why

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Old 12-10-2010, 10:16   #152
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In regards to paper versus paperless(electronic). I carry and use both. I have delivered yachts with owners who get their heads stuck in the computer. The zooming in and out in order to see greater distances has caused problems when I have allowed them to navigate. when zooming out they forget how far they really are off shore and it looses needed detail. Having a paper chart is reliable and is easier to refer to when navigating.
On the same note the coast guard has a distain for GPS, they don't test on it when obtaining a commercial license, and one of the requirements of boat documentation and operation require you to have a paper chart of the area of operation. it really looks bad when your excuse for running aground or any other incident is that your GPS said it was clear. Or my favorite, when I was a USCG SAR coxswain and these systems were being introduced actually had some declare a MAYDAY because their GPS went down.
I use both and I always remember the rule that states " do not rely on any sole source of aid to navigation". So I utilize all the resources when navigating to develop a picture and route plan. I have experienced times and or places when the GPS has lost signal. Another word of advice is to never force a course you should take into account wind seas traffic and safety of vessel and crew and don't forget to verify with non electronic(GPS) tools.
Hope that helps possibly a little long for a thread. In addition having responded to a few SAR calls where the owners left the bridge for to long with GPS and Auto driving the boat and ran aground hard. Remember that despite all that equipment a boat doesn't have eyes connected to a brain and doesn't reason it just drives a course. a rule states to maintain a live and active watch at all times while underway.
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Old 12-10-2010, 15:29   #153
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Greetings and welcome aboard the CF, west coast Cpt. B.

Not at all long, and certainly an excellent first post. Thanks!
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Old 12-10-2010, 17:50   #154
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It's a weird artifact that the quest for the universal datum has meant occasional decreases in chart accuracy in some locales. It's such a pity that the earth couldn't be bothered to be a sphere, or even a regular sort of spheroid, but instead has those little bitty lumps and hollows that vex that chartmakers so much. Geez, someone could have done a better fairing job on the Earth.

Stephen and Linda Dashew related a cautionary tale in their "Bluewater Handbook"; approaching Espiritu Santo Island once they ran their boat into an uncharted coral reef in a place that should have been clear for several miles. It turned out an earthquake just a year before had raised the elevation in one spot and created a shoal that was known only to locals.
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Old 12-10-2010, 18:52   #155
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Thank you both rgscpt and gordmay. Yes rgscpt although the datum thing may change things slightly, as well as the date the chart was published affect it's reliability, or how up to date the chart-card is in your GPS, it's better than nothing, and doesn't require batteries.
As far as the passage from the book, I will again say" In addition to having responded on a few SAR calls where the owners left the bridge for to long with GPS and Auto driving the boat and ran aground hard. Remember that despite all that equipment a boat doesn't have eyes connected to a brain and doesn't reason it just drives a course.". A side note sometimes map makers change things just to make sure not to in fringe on copyright laws(Thomas Bros. maps for certain cities have the one way streets printed the wrong way and when compared to what mapquest feeds you and what you may know from your local knowledge, I like my brain)
Adding to this nothing beats blue water experience, in being able to read changes in the waters color and the slight change in the way the water is moving with the eyes of an experienced person on watch to avoid things in an unfamiliar place.
I think we are all saying the same thing, use all the aids to nav. you have, don't rely on any single source and exercise common sense with good seamanship. GPS is a great aide, but would I turn on auto pilot and the nav. plotter and go below to make it with my wife? I will wait till in port or the mate has the watch : ).
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Old 12-10-2010, 20:12   #156
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Quote:
I think we are all saying the same thing, use all the aids to nav. you have, don't rely on any single source and exercise common sense with good seamanship
I think another bit of advice would be to memorize one's route to an anchorage so you don't have to be running back and forth to one's nav station or be buried in a chart and not paying attention to the situation. Manual control, situational awareness, and knowing what to be looking for from having studied charts--paper and electronic--is much better than trying to navigate staring at a screen or chart.
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Old 12-10-2010, 22:39   #157
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Originally Posted by goboatingnow View Post
Sorry absolute rot, in general since almost all current digital charts are derived from paper . any errors present will apear in both paper and digital, these include, mis alignment, missing features, incorrect rendering,etc. It matters not whether its a chartplotter or a paperchart one is not any better then the other when errors are present in the original survey.
Given the common source for chart data I agree that both paper and plotter will be equally at risk to incorrectly shown or missing features.

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ITs a nonsense statement to suggest that paper charts are better when datums are not so good, the resulting posiiton errors will be there irrespective of the position fixing method used. All that GPS has reveled is that previously hidden errors due to sextant error are now visible usuing GPS.
Not so. The root interest in determining where you are is to avoid hitting anything not to determine your Lat/Lon. In poor datum areas GPS can be off in excess of 1nm relative to actual hazards, I have heard 2 or 3nm but that's pretty rare I think. Using visual navigation you can fix your position relative to things you don't want to hit to less than 0.1nm with a modicum of care. Radar navigation is probably about as good depending on how good the target returns are.

That is the crux of the issue. GPS tells you where you are relative to the big wide world, visual and radar navigation tell you where you are relative to the things around you. In good datum areas the two co-incide well and there is no problem.

If you are using a chart plotter that implies position determing via GPS. How many chartplotters let you plot a visual bearing to check the GPS position? That's not a rhetorical question I really don't know. I expect laptop programs will do it just fine, but the chartplotter/GPS units?

With paper charts you may be using GPS to get a lat/lon and plotting that which would be no better than the plotter, but you can also take a round of bearings and the plotting is just as easy or difficult as plotting the lat/lon.

In poor datum areas paper has the advantage because it is not really much harder to take visual bearings and plot them than to take a GPS reading a plot it. With plotters you fall into the routine of letting the electronics figure everything out because it's so easy.

But, you say, in poor datum areas I will check the GPS results against visual bearings. But if you aren't checking regularly, how will you know when you get into one of those areas. For people that only have a chartplotter, how often do you take visual bearings to check the GPS position, or have you ever done it?
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Old 12-10-2010, 23:55   #158
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One thing these threads always seem to ignore is that everything that can be done on a paper chart can be done on an electronic chart.

Visual position fixes, dead reckoning, following the depth contour etc, etc, etc. all can be done on an electronic chart. Often it is easier to do these things electronically - at least I find it so.

Using electronic charts does not by default mean blindly trusting the GPS position. Using multiple means to determine position is good practice, regardless of whether you are plotting that position on paper or electronically.

So the only real argument between the two mediums is one of reliability. Is a paper chart more reliable medium than an electronic one?

The answer to that really depends if you think it more likely to be struck by lightning or have your chart eaten by the goat.
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Old 13-10-2010, 02:08   #159
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Is a lightening strike likely to damage the battery powered hand held spare model at the bottom of the spinnaker locker? I hear even goats can get in them distant corners.
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Old 13-10-2010, 02:48   #160
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I defy anyone to plot a position on a paper chart quicker than it gets onto my electronic chart.

I defy anyone to use a paper chart in the cockpit with pencil, ruler and spray to the same capacity I can with my helm mounted plotted.
What Astrid said is important - I am at the helm controlling my boat where the paper person is below fumbling for the light switch...

Maybe we could have the Navlympics!!
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Old 13-10-2010, 02:49   #161
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Radar overlay is an excellent means of checking the GPS/datum/Chart.
Its easy to do, provides a continuous update and takes no effort so its done all the time.
It can only be done on an electronic chart.

Depth is another often useful way of checking the GPS/datum/Chart.
This is much easier with an electronic chart.
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Old 13-10-2010, 04:38   #162
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I defy anyone to plot a position on a paper chart quicker than it gets onto my electronic chart.

I defy anyone to use a paper chart in the cockpit with pencil, ruler and spray to the same capacity I can with my helm mounted plotted.
What Astrid said is important - I am at the helm controlling my boat where the paper person is below fumbling for the light switch...

Maybe we could have the Navlympics!!
Paper, computers, Thor and the Goat at 9 paces!



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Maybe you have never been to a place where the electronic chart is 1/2 mile (or whatever) out. It is most disconcerting to have the screen tell you that you have anchored on top of a hill or that the reef 50 yards off your bow doesn't exist.

It is even worse to have the screen present an island to you as a shapeless green blob with no soundings at all. Garmin Bluechart presents every one of the Northen Marshall Islands (except Kwajalein ) as such. Who cares about the reef that shows up on the French navy paper chart from 1895 but not on the screen ? True story - Hiu, West side.
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Old 13-10-2010, 04:56   #163
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Maybe you have never been to a place where the electronic chart is 1/2 mile (or whatever) out.
I've already sailed places where the charts are out... paper and ecn.
Thats one of the things about being 3,000 miles from finishing a circumnavigation. Fewer people can treat me like an idiot Kinda been there, done that know how to survive thanks very much


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Old 13-10-2010, 05:15   #164
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Well I'm still not going to dump my old French charts. Every time push comes to shove they prove more accurate than my C Map chips.
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Old 13-10-2010, 06:31   #165
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The discussion is flying loose and fast with the term "Datum." Chart Lat/Long errors are not a result of the "Horizontal Geodetic Datum." The word "Datum" is used twice in regards to nautical charts - first as I just mentioned as a map construction system and secondly as the Sea Level reference for tides.
- - What causes errors in the comparison of Lat/Lon's between your GPS and your chart is plotting errors created by trying to place "straight line" meridians and parallels on a graphic representation of a "pear-shaped" (somewhat round) planet. Here is the definition of Geodetic Datum:

"Horizontal Geodetic Datum: The definition of the relationship between the ellipsoid adopted as the model of the Earth's shape, and the Earth itself. Though there are hundreds of datums in use, most are only locally valid.
The WGS-84 datum is global in scope and positions obtained by satellite navigation systems are usually referred to this datum. Therefore a correction needs to be applied to a WGS-84 GPS position to agree with charts using other horizontal datums. For example to correct WGS-84 to the European datum, add 0.06'N, 0.04'E to the WGS-84 position indicated by the GPS. Fortunately, most GPS receivers may be set to display positions in several other datums besides WGS-84. "


- - The chart maker creates and adjusts a mathematically derived spheroid that matches as many "real" points on the earth with the projection onto a flat piece of paper so that taking directional relationships remain as accurate to real life as possible. This spheroid is named a Geodetic Datum and if it is different from others already created it is given a new name.
- - GPS receivers normally have up to 140 Geodetic datums stored within its memory. Getting to them was easy with the older GPS's but in the new models it is very difficult to change away from the standard WGS-84. WGS-84 was picked as the standard world-wide datum for this reason. However there are areas of the world where WGS-84 is not very good and Lat/Long relationships are noticeable offset. The concept of "one size fits all" does always work as your distaff partner may point out to you. And most importantly there are a considerable amount of charts used by nautical vessels especially "out of the way" places in non-1st world countries where the map was never "re-registered" to conform to WGS-84 yet the nautical map is included in a chart kit/CD/chip.
- - I personally use the term "offset" to describe Lat/Long disagreements between your GPS position and that position when transferred to a nautical chart. The above definition describes having to add xxN/S and xxE/W to bring the paper chart into agreement with the observed GPS Lat/long's.
- - The physical positional relationship of one chart feature to another chart feature, ignoring Lat/Longs, is usually quite accurate unless you are using 15th century to 18th century maps which are very interesting to see.
- - Some ENC charts can be manually "re-registered" by the user to reduce or eliminate the offset but a lot of others especially vector charts cannot. This is where when sailing into a strange and wonderful new harbor/cove/whatever it is sometimes necessary to turn off or totally ignore the "little boat" symbol generated by GPS and use the displayed chart as if it were a "paper chart." You are using the virtual "paper chart" to discern the visual directional relationship between one feature and the feature of interest to you. Otherwise known as old fashioned visual navigation.
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