How to get the best data for import

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How to get the best data for import Empty How to get the best data for import

Post by fergusbass on Sun May 10, 2015 2:13 pm

I will be buying AutoChart (not Pro) soon and I want to do things right by understanding things, not through trial and error.  I don't want to record a bunch of data only to have it be inaccurate and/or useless.

We've all seen situations where the depth reading isn't accurate.  Perhaps this is because of vegetation or maybe because it is extremely shallow water and we are getting double readings.  Sometimes the depth readings are a bit obscured because of a sharp change in depth and part of the cone is covering a shallower section and part in the deeper part.

As I understand it, you can record track log or all data.  Is it true that recording all data will make for a better map?

If a narrow beam is used, very little bottom is covered in shallow water.  Is that a bad thing?

If a wide beam is used, depth changes may be obscured like I described above.

What should a person do when in vegetation to make sure that true depth is recorded, not a false reading because of the vegetation?

Thank you for your help.  I want to learn from the experience of others.


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How to get the best data for import Empty Re: How to get the best data for import

Post by CamoHunter on Wed May 27, 2015 12:59 pm

The accuracy of your map, and acquiring accurate depth readings, all depends on how well your transducer is set up on your boat. Making sure it is set up properly so you don't lose bottom readings at high speeds, and making sure it is straight down are important considerations.
Beyond that, you'll always want to use the narrowest beam possible, to create depth maps. The reason is, sonar is casting a circular cone on the bottom and it will only read sonar to the highest return. Therefore, the wider your cone angle gets, the higher chance you have of hitting a high spot off to the side, and reading a shallower return than what is actually directly under the boat.

So, always have 200khz beam on when collecting sonar recordings. You can have both 83/200 on if you want, and the depthfinder will record the depth from the 200khz.

You may think a wider beam would collect more depth data, but that is not the case. It still only reads ONE single depth reading just like a narrower beam would do. But the wider beam actually is less accurate than the narrower beam.

Hope that makes sense.


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