Dangers in Electronic Charting

[Sandero]

Sully,

Don't be a silly captain. My point is that a sailboat can navigate without electricity as evidenced by the fact that sailors have been at it long before Thomas Edison "discovered" practical uses for electricity.

Your points about single handed sailing without electricity are valid, but in fact I can measure speed without leaving the helm. Here's how:

I have a string with two small floats attached. One at the end and one 60' upline. And the string is secured o the pushpit. To measure speed while at the helm I toss the ball abeam into the water and not the time on the second hand of my self winding watch and the string pays out. When the second ball pops overboard I have moved 60' or 1/100 of nautical mile. Can you do the math? 1 knot = 6000' / hr (60x60) or 6000/3600 = 1.66 ft/ second

For a lead line I can use a small lead fishing sinker and a string marked at say 5' intervals to "feel" the bottom and determine the depth.

As much as I depend on the autopilot I can leave the helm for brief periods and I can even get the boat to sail on her own if she is well balanced on certain points of sail.

The long and short of this is. If my electrics when south I would resort to these basic sailing skills and carry on. Sure if I were in unfamiliar waters I would be nervouse and be proceeding slowly. And I do have a chart "table" in my cockpit - 2 in fact, one is the lift up lunch table attached to the pedestal and the other is the companionway slide cover which contains a hinged plex panel to hold down and protect a paper chart and I can plot ON it using markers! How bout dat!

But I love me some electricity. It sure makes all this easier, don't it?

[swagman]

Yes I agree with the dangers.

I alway knew it would get worrying the day I saw them using those new fangled printing machines to reproduce charts. How ever could someone assume assume a machine could do it better than those scribes copying it by hand, eh??

My worries were confirmed when most stopped placing a bowman heaving a lead line - and loosing those other chaps counting knots on the trailing string was also asking for trouble.

But when they suggested the astrolabe was being over taken by the sextant well, you know, I told them they were really all taking this so called progress just one step too far.

But strangely no ones sympathised with my worries - at least not so far. As lots of sailors are conservative chaps, I can't understand why not:-)

JOHN

[btrayfors]

I think Nigel was aiming at the (very, very large) group of mariners who know little about navigation, who grew up with the wonderful electronic gadgets which provided entertainment and, occasionally, utility; and who tend to trust things electronic to a degree they shouldn't.

Virtually all us "old hands" with extensive navigational skills and experience already know to distrust electronic charts, paper charts, uncalibrated compasses, etc. We tend to place more reliability on fathometers, radars, our senses of smell, hearing and the venerable Mark I eyeball, but even these tools can occasionally deceive. Bottom line for any experienced navigator: use all tools available and trust none 100%. You've gotta insert some gray matter into the navigational equation, and process the input data according to situational factors.

Most distressingly, in my experience sailors able to do this are few and far between. It's not that they're stupid; to the contrary, many are highly intelligent. Nevertheless, they often seem clueless.

Last week I captained a 40' plus power boat about 25 miles downriver for haulout and survey. (OK, OK....sometimes I do wander to the 'dark side'). The prospective owner was aboard for the ride down and back. He was a very intelligent 40-ish fellow who actually had a considerable amount of Search and Rescue experience with the Civil Air Patrol. However, at one point he asked me how I knew where the channel was, and how to avoid shallow water and obstructions.

It turned out, he had no knowledge of navigational charts or the buoyage system. Not his fault. He wasn't slow or obtuse. He'd just had no exposure. And, he was about to buy a 40'+ boat to take his family out on.

I think he represents a seriously large segment of sailors who are actually out on the water these days. While most have some cursory knowledge of charts, almost none have in-depth understanding of the factors which go into their compilation and the resultant accuracy of plotted features.

Many sailors also know nothing of GPS accuracy, electronic charting accuracy and problems, etc. They also are unaware of the differences between a raster chart (essentially a perfect 'snapshot' of a government-porduced paper chart) and a vector chart on their chartplotter (which was produced by god-knows-who, digitized by bored and low-paid employees, and validated by heaven-knows-what-process).

I don't know what the solution to this problem is, but I think it can only lie in the realm of education. The US Power Squadron, Boat US, yacht clubs, and other boating organizations really need to mount a country-wide (worldwide?) program to educate boaters to the basics of piloting and navigation. IMHO.

Bill

[Pelagic]

Swagman, I don't think anyone questions the fantastic benefits of ECS and all the other improvements. It was just a discussion on the fixed and variable errors that many may not be aware of

[imagine2frolic]

I wouldn't use a small fishing weight. I would use a really heavy one with as small a line as possible. Making any speed at all the weight won't drop straight down, and the same with any current. I use a shackle bigger than my fist......

[MidLandOne]

Jeez I agree alot with Sean here and he is a cat owner too, what is the world coming to .

The feeling I got from Calder's article was he overplayed the deficiencies of electronic nav and did not really stack those up against those of the traditional style with paper which has its own problems so giving the impression that electronic may be inferior. Whereas the opposite is true.

And his errors tended to emphasize that in my mind eg he said error circles are not possible, whereas a cheap charting system on a notebook will let you create danger zones of whatever size one desires AND shout/flash warnings should your heading vector no matter how ever long you have set it enter that, so, in fact vastly superior to paper.

All I am leading up to here (at last ) is that there may be room for a magazine article (maybe it would take a series ) with a broad and balanced view both with respect to paper and electronic and with respect to making correct choices as to functionality in electronic equipment and to security of chart accuracy through choice of chart producer (and for those of us in the USA the best charts are free, and for us in NZ they are nearly free being only around USD50 for the whole catalogue).

And Pelagic, in case you are wondering, don't take me as criticising the article in a destructive way - I really appreciate your posting the link to it and appreciate the value in it.

John

[David_Old_Jersey]

I'm sticking to me GPS. No batteries required. and it floats.

[Morgan Paul]

David, I like that pirate girl.

[David_Old_Jersey]

Originally Posted by Morgan Paul

David, I like that pirate girl.

That's why I have been quiet the last couple of days - been kinda busy


I am quite taken by an Astrolabe:-




The Mariner's Astrolabe

"can you use a Sextant?"

"no - only an Astrolabe "

[JiffyLube]

Electronic navigation is here to stay. Just as the electronic calculator made the slide rule obsolete, so will the sextant give way to electronic navigation...it'a just a matter of time. If it's good enough for the Army, Navy, Marines, Coast Guard, NOAA, and NASA, it's good enough for me.

One thing that I have found very valuable with electronic navigation is, the saving of certain tracks of places I've been before. When I go into a harbor or marina for the first time, I save and name the approach tracks into those areas. If I go back to those harbors or marinas again, and the weather or night conditions make entering a possible hazard (and I don't have an option of staying out), I pull up the track of the area I'm entering, and follow it religiously to safety...at slow speed. Nothing is as accurate as a GPS track, if cruising under instruments alone.

[David M]

All these different posts with all these different ideas really goes to show that navigation is just as much an art as it is a science. The art is in knowing what to trust, when to trust it and where to trust it...and of course, when not to trust. When and how to digest all this information and sometimes contradictory information, is the real art of navigation. The science side to navigation is the easy part.

[David_Old_Jersey]

Originally Posted by David M

All these different posts with all these different ideas really goes to show that navigation is just as much an art as it is a science. The art is in knowing what to trust, when to trust it and where to trust it...and of course, when not to trust. When and how to digest all this information and sometimes contradictory information, is the real art of navigation. The science side to navigation is the easy part.

+1

I view "Navigation" as the art of getting from A to B safely, using whatever tools are available. Reading a chart is simply one tool, whether paper or electronic. IMO a prudent Navigator factors in the risk of a degree of error or fault in his calculations, Nav Tools or boat.

Kinda got used to making passages to France when I was a kid, no GPS, no Autopilot and sometimes no log....so not knowing exactly where one is all the time is a very comfortable situation - and IME makes a landfall all the more a happy event! (Note that I have no Internet Links to insert here to "prove" any of this - wot with their being no internet back then ), but GPS and Autopilot is IMO the way to go, both for converniance and safety overall.

Chartplotter? Not yet! (but have sniff at some gear from a 40 foot Mobo that is upgrading ) - but back up to my GPS is.......another GPS, which is backed up by another GPS (I fixed and 2 handheld - not a deliberate decision - just what has been acquired over time)....and papercharts.....blue water would I learn a Sextant? I would like to think so (partly for fun!), but hand on heart.......probably won't.

When / if I get a Chartplotter I would probably cut down on the Paper charts - but I think I would always want at least one for the area I was in that allowed me to plot my position, even if the scale was not much use for close inshore navigation....but at least I could find a port!

[Therapy]

Originally Posted by David M

...navigation is just as much an art as it is a science. The art is in knowing what to trust, when to trust it and where to trust it...and of course, when not to trust. When and how to digest all this information and sometimes contradictory information, is the real art of navigation. The science side to navigation is the easy part.

That is why monkeys don't do it.

[Maren]

Originally Posted by David_Old_Jersey

I am quite taken by an Astrolabe:-
The Mariner's Astrolabe

Oh, that's nice! A lot of the ones seen lately are utter trash.

But here is one that is not as attractive, but is inexpensive and customized to your region.

[donradcliffe]

Here is a case in point:

Today I came into Bermuda for the first time. Using SeaClear with chart 26030, it showed my position as 13 miles south of Gibbs Hill on the south side of the island. The only radar return I had was 21 miles out. Further investigation and comparison with other charts showed that the coordinates of Bermuda on chart 26030 were 8 miles out of position!

I use SeaClear because it is free and the AIS system works with it, but today's experience points out again that it is important to use as many inputs as possible and make sure that everything is consistent.

For the record, I used electronic charts to come into Bermuda, but also:

1. Slowed down for a daylight arrival so I could see features and water depth.
2. Transferred enough waypoints into a handheld GPS to find and navigate the channel, and stored the handheld in the oven to protect it from lightning stikes.
3. Had a backup laptop with all charts and programs copied.
4. Used the radar to calibrate the charts (my other electronic charts were accurate to within 0.1 mile)
5. Set the depthsounder alarm to 25 feet.