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Old 18-07-2020, 00:02   #1
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Show depth in shallow waters in vector charts

Sorry maybe this is a stupid question. I am not sure how to interpret depth information in shallow waters. See screenshot, there are no numbers only dark blue color and a black line in the middle. What is the depth of water there?Click image for larger version

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Old 18-07-2020, 00:23   #2
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Re: Show depth in shallow waters in vector charts

In the configuration you can define to which depths each color applies:



In your area the depth drop is so high that there's hardly any separation between colors. You can almost approach the shore without problems because the depth falls immediately:



In other areas, the colour scale is more evident:



The same scale in both images.
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Old 18-07-2020, 00:38   #3
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Re: Show depth in shallow waters in vector charts

The answer is, it depends. I suggest reading through this post to understand the roles of the different colors and how you might adjust your settings for your vessel:

https://www.myseatime.com/blog/detai...afety-settings

OpenCPN doesn't have all of those settings, but Pinguino has provided the proper screenshots for you.

Also, the chart you are using appears to be too small-scale to contain detailed sounding information, so I would use it with caution. If your collection includes a more detailed chart, zooming in may reveal it.
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Old 18-07-2020, 11:56   #4
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Re: Show depth in shallow waters in vector charts

What pinguino wrote is totally correct.

Below is a chart with setting 3m/6m/10m and the same chart with depth setting 1m/3m/6m. Detail here is the tidal difference here is about 2m. This means the dark blue color I cannot sail and the light blue color I can when the tide is right.

The pittfall is the levels need to be included in the chart data. I have some charts with a fine level display (each 0,5m) and some with only the minimum levels like 1m, 3m, etc.. So if I try to select 1,5m the display depends on the available data.

You'll have to find out what works best for you (your boat and your preferences) and the charts you are working with.


PS another pittfall, the depths you want to show may differ between different charts. Sometimes you may want to change the setting to prevent "all white" maps.
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Old 18-07-2020, 12:33   #5
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Re: Show depth in shallow waters in vector charts

Actually in above chart the chart heights are 2m/5m/10m.
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Old 18-07-2020, 14:32   #6
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Re: Show depth in shallow waters in vector charts

Ok, now that I'm a bit more awake, below is an example of how the depths work. I've set both the safety depth and safety contour to 8 units. (I believe OpenCPN has them as a single setting.)

The safety depth is the only value referring to individual soundings on the chart, all the others refer to depth contours. As a result, they will be rounded up to the nearest contour the chart supports. So, even though I entered 8, the actual safety contour ended up drawn along the 12 unit contour.

This means there are sometimes cases where it's actually OK to cross the safety contour. You can see most of the soundings there are still gray, except for the two in black close by where the channel enters the shallow area.

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Old 18-07-2020, 16:40   #7
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Re: Show depth in shallow waters in vector charts

Here we go:- Tools, Options, charts, Vector Chart Display
Change the settings this way:-
Shallow depth:- 1.00 in metres or 3.28 in feet
Safety Depth:- 50.00 in metres or 164.04 in feet
Deep Depth:- 5.00 in metres or 16.40 in feet

Then your soundings on vector charts ar well visible and not faint up to 50.00 metres.

Is that clear enough?
Good luck.
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Old 20-07-2020, 07:44   #8
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Re: Show depth in shallow waters in vector charts

Thanks to all, for help and clarifications. I adjusted the settings to my needs and everything looks fine now :-).
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