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Old 09-11-2016, 06:50 AM   #1
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interesting

When Electronics Lie | Boating Magazine
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Old 09-11-2016, 07:20 AM   #2
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Good topic.
In very shallow water the sounder sometimes ignores the first bottom echo and shows the second. IE bottom readout is coming up 4.5 ft, 4.0 ft, 3.5 ft, 6.0 ft, 5.5 ft thump hit bottom. This is why I prefer a graph fishfinder over a strickly digital DF. You can easily see this happen.
Another is using too much Sea Clutter adjustment on radar. Targets close to the boat disappear.
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Old 09-11-2016, 08:10 AM   #3
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Agree with High Wire on the radar. Sometimes I prefer my old Furuno CRT unit that I almost threw away. It's easier to make manual adjustments to tune in just what I want to see.

I also agree with the article on keeping electronic charts up to date. While it's true that the rocks don't move, channels do. Buoys are moved or removed. Fish farms spring up. New rocks are "discovered." Lighthouse and foghorn characteristics change. Bridges are rebuilt with new clearances. New regulations are enacted. Offshore platforms, wind farms and pipelines are built.

Even with charts less than a year old, I've seen all of these, with the exception of the "new" rocks. That one I just barely missed - by sheer luck. It was published in the LNM the following week.
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Old 09-11-2016, 09:27 AM   #4
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I've experienced all 3 scenarios from the article. I think in many cases experience and paying close attention are needed to remain unscathed. I really really try not to rely on luck but sheer luck has saved me a couple of times.

Ken
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Old 09-11-2016, 09:45 AM   #5
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I have to be a little nit picky on the article title though...

While good info....electronics generally don't lie...they just spit out whatever limitation is there. There is no intention to ceive on their part....at least not the possessed ones...

We as operators should be aware of all the equipments limitations, beyond electronics....even to include the captain.

Sometimes the captain is misinterpreting perfectly good data.

This can be true with more and more input....loss of situational awareness is something that takes discipline. Some captains can focus better than others and even old timers suffer from over confidence.
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Old 09-11-2016, 10:00 AM   #6
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Recently had a similar situation with Navionics' depth readings. Was looking for a depression to fish in. Electronic chart was showing 5-12' going toward the hole. I thought the boat was performing sluggishly and noticed the depth sounder flashing. Oops. Got free before the tide went completely out. Severe pucker. Was able to paddle dink around taking manual soundings with an oar to note where the bottom started to get deeper, and with a few maneuvers get her free.

And I updated my chart that morning. The bottom was sandy thank goodness, but lesson well learned. Won't go there again.
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Old 09-11-2016, 11:30 AM   #7
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Navionics has LOTS wrong with it, depending on the location. Harmony Islands is a good example, Navionics got most of the thing wrong. Numerous coves that have been surveyed and appear on Canadian charts show as blank spaces on Navionics. C charts are virtually the same but their errors are all different. I guess Canada is not a big enough market to worry about accuracy, after all you have to agree to a disclaimer to use them.
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Old 09-11-2016, 06:34 PM   #8
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I found on my Standard Horizon GX2200, the heading can be selected True or Magnetic. The T or M letter changes on the display but the value of degrees always stays True!
My Garmin 5212 plotter shows us transiting over land for most of the Okeechobee Waterway.
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