NOAA ENC Charts Question

[transmitterdan]

Originally Posted by pkrawetzky

Ok I changed a few options on the vector display screen and it identified the channels with more precision. So it now looks much better.

I was not aware there are options that affect accuracy. What options did you change?

[pkrawetzky]

Thanks. The images are pretty small but I have to agree seems the RNC's are much more accurate.

So I guess that goes back to my question, what is more popular to use RNC's or ENC's?

[pkrawetzky]

Instead of using the default I used Mariners Standard for the display choice and that seems to have take away a lot of the "chatter" on the charts. I was then able to see the channel better but I still think the accuracy of the ENC's is not as good as RNC's.

[transmitterdan]

In general, if there is a real discrepancy between RNC and ENC charts in the US I tend to believe the ENC will be more accurate. The reason is that ENC data is easier to update than RNC data. So if a correction happens it will usually hit the ENC first. And ENC charts were created more recently than RNC charts. Some RNC charts are 50 years old or more.

Can an ENC chart be wrong? Sure it can. That's why we have eyes, brains, depth finder and radar to double and triple check our position.

[transmitterdan]

Originally Posted by pkrawetzky

Thanks. The images are pretty small but I have to agree seems the RNC's are much more accurate.

So I guess that goes back to my question, what is more popular to use RNC's or ENC's?

I doubt the RNC is more "accurate". There may be a 1 meter difference between them but that probably exceeds the expected accuracy of either one. The true position is probably somewhere else. And most commercial GPS units don't have precision enough to get us within 1 meter anyway.

Changing what is displayed doesn't move the chart position around. So I don't think it's correct to say changing display options affects the accuracy. It merely affects the ability to see things.

If you clicked on the option to "suppress blur/fog effects on overzoom" that did not change the ENC accuracy. It merely gives a false sense of precision. At really high zoom levels the display shows a precision that does not actually exist in the chart data thus the foggy display is to remind us of that.

[pkrawetzky]

I agree. Charts are only a tool. Knowledge and experience play a significant role as well.

Thanks for the input! I appreciate everyone's response.

[transmitterdan]

One thing that "annoys" me is the modality of the progress bar dialog when converting ENC files to the internal format. This box pops up in front of all other windows instead of just in front of the OpenCPN window. So if I minimize O this dialog box keeps popping up and stealing the focus. If you have a long conversion in process it gets annoying really fast.

[rgleason]

Have you been up there since dredging this fall? I think they stopped at Mystic Seaport north dock in front of the tent.

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[rgleason]

To bad the dredgers don't map depths. Thats where users crowd source data might help but accuracy would be derived by statistics to filter out instrument and user anomolies. I believe this is a different standard than Noaa. I wonder if there is any indication of how accurate this approach can be?
I supose it is entirely dependent on the number of reports in an area to provide reliable results...

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[rgleason]

Agreed about the senc progress bar modality. Perhaps it should be entered into the Tracker so this does not get lost?

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