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Lost Waypoints

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PZell
Admiral

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USA
548 Posts

Initially Posted - 11/23/2003 : 12:56:34

I have a Magellan 310 GPS. It's about 3 years old and has been working fine. Last Friday I went to punch in GO TO landmark for
our marina channel and zip. Subsequently discovered it had mysteriously deleted all my waypoints. Saturday I went for a nice sail around the bay and reentered a few waypoints and the unit seems to work OK. Anyone have any ideas before I call customer service.
That's a wake-up call to not depend on these electronic gadgets for
all your navigation.

Paul C25FK Sparky
'PZ' W7JVY KFS/KTK/KLB/KOK/WNU/KPH/WCC/VAI/VAJ

Edited by - on

Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 11/23/2003 : 13:28:21

Paul, Good point.

As a Ham, your likely familiar with what is called "Single Event Upset". Those of us who worked the various Ham Radio satellites were quite familiar with them because they happen fairly frequently (perhaps a few times a year) in a space environment where a large radiation particle collides with the fragile memory chip in a way to slip a bit (a charge to a memory cell).

We're told that they occur terrestrially also but in fewer incidents. I experienced a mobile 2 meter synthesized rig that on one occassion expereinced a single event upset with the processor failing to provide logically opperation. Whether it was radiation induced or whatever... a system reset solved it and it was the only glitch the radio ever experienced.

If the problem can't be ascribed to the battery back up for the memory... it may have been SEU.

Edited by - Arlyn Stewart on 11/23/2003 18:24:51

Oscar
Master Marine Consultant

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USA
2030 Posts

Response Posted - 11/23/2003 : 18:15:48

Without getting into too much detail I can tell you that in the flying business way points are provided in databases that are verified/updated bi-weekly. These data bases are FAA certified and expensive. When we create our own way points, as in the "tracks" that go across the Atlantic, and are in different locations every night based on Meteorological conditions (storms/winds,) there are procedures to check and double check these points.

What I'm getting at, is that on my boat for a lack of desire or someone to verify my way points on a regular basis, I do not keep a collection of them. Every time we go out on a trip I dump the data base and start fresh.....This way I am assured that I know what is what, and that there has been no corruption of the data. GPS will take you where ever you tell it to....even the wrong place. I would not be comfortable going to a way point that I created a long time ago...

Oscar
250WB#618 Lady Kay on the Chesapeake

Edited by - Oscar on 11/23/2003 18:19:09

PZell
Admiral

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USA
548 Posts

Response Posted - 11/23/2003 : 18:24:11

Good pointOscar. And one lesson I learned. Write down
the coordinates of my desired waypoints. I had only noted
which buoy, channel, pass, etc. that each waypoint was on
most of them. That way I can refer to my note page in the
ship log and reenter any waypoint at any time.

Edited by - on

ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 11/23/2003 : 18:44:43

"That's a wake-up call to not depend on these electronic gadgets for all your navigation. "

Excellent point Paul. Never rely on a 'single point of failure' for navigation. This is one reason why I advise against "all in one" electronics packages unless you keep a seperate backup. (integrated Depth/GPS/Radar/Washer/Dryer/Microwave Oven... whatever)

It is also a good practice to keep a 'dead reckoning' track going in your head, if not on a chart. About where am I? Am I north or south of point XXX? What magnetic heading have I been running on? Which way is the tide/current setting? What would I do if the GPS quit?
Always have a backup plan.

I've worked with computers for the last 25 years or so... and people ask me why I keep the most critical network information printed on paper.

Edited by - on

PZell
Admiral

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USA
548 Posts

Response Posted - 11/23/2003 : 18:53:13

In this case it was not critical. I knew where I was and
where I was going. I just happened to input the goto to
get the exact distance to destination so I could figure
an ETA in my head. But if I had been on the coast between
San Francisco and Half Moon Bay in the fog, it would have
been scary.

Edited by - on

deastburn
Captain

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USA
334 Posts

Response Posted - 11/23/2003 : 23:21:55

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I experienced a mobile 2 meter synthesized rig that on one occassion expereinced a single event upset with the processor failing to provide logically opperation. <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Arlyn: And you lived to tell the tale?

Edited by - on

Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 11/23/2003 : 23:33:57

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">And you lived to tell the tale?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Yes... to botch that paragraph and a few more....

Edited by - on

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