Keep off the rocks!

[GHA]

There's a big discrepancy between Google Earth position of my mooring and gps, if I followed GE lat/long, I would end up high and dry. C Map also shows me over the banks when I'm in about 4m of water.

That looks like something weird with Lat/Long display in google earth, I never use GE but import sat images into opencpn, or just have a look in SasPlanet. The images are very accurate in OpenCpn/SasPlanet so far.

And the opencpn track imported into sasPlanet pressing keyboard shortcuts between Yandex Sat, Google Sat, Bing Sat, navionics, navionics sonar and Cmap >

 

[GHA]

W Coast of Scotland, various places charted 100m out - both vector, raster and satellite images. but it is improving a lot over the last 30 years. it can be quite variable between the various info sources. but never quite believing any of them 100% usually helps...

Do you have a Lat/Long of such a place for a look?

 

[Graham376]

That looks like something weird with Lat/Long display in google earth, I never use GE but import sat images into opencpn, or just have a look in SasPlanet. The images are very accurate in OpenCpn/SasPlanet so far.

My boat is top left in the GE image you show, compare that lat/long to gps position noted by diver on mooring - 37.00'520N 07.50'490W

 

[bikedaft]

Do you have a Lat/Long of such a place for a look?

eilean mhor, mccormaig isles, and west loch tarbert Jura - both charted a while ago... (Antares are spot on, however)

55deg 54.932N 5deg 44.053W
55deg 57.520N, 5deg 56.212W

reviewing tracks however - they are a lot better than they used to be...

the satellite imagery seems good although it does not show up all the rocks, even with only a 2m keel.

 

[GHA]

eilean mhor, mccormaig isles, and west loch tarbert Jura - both charted a while ago... (Antares are spot on, however)

55deg 54.932N 5deg 44.053W
55deg 57.520N, 5deg 56.212W

reviewing tracks however - they are a lot better than they used to be...

the satellite imagery seems good although it does not show up all the rocks, even with only a 2m keel.

Seems pretty close between Navionics, cmap, googleSat & Bing Sat in SasPlanet>
A few metres out but not anywhere near 100m>

 

[GHA]

Purely out of curiosity, where on earth are you sailing and what are you up to for such fine tolerances in such far-flung places to be so relevant?

Much is just academic, interesting to see how the sources tally up. But even in Europe you can be well away from any useful charts, maybe not vital to have charts way up a river but nice to have something >>

I do use sat images a lot, really useful, the 'could be 100m out' rang some alarm bells but yet to find anywhere the sat images don't largely tally up.

 

[GHA]

My boat is top left in the GE image you show, compare that lat/long to gps position noted by diver on mooring - 37.00'520N 07.50'490W

Take it you meant 7deg56W..

Looks about right in openpcn, lesson being don't use google earth

 

[Graham376]

Take it you meant 7deg56W..
Looks about right in openpcn, lesson being don't use google earth

I'm booked into the yard on 11th so we'll have a look at it then after checking onboard gps.

 

[doug748]

More on the San Blas Islands here:

e-charts for san blas - Cruisers & Sailing Forums

 

[GHA]

More on the San Blas Islands here:

e-charts for san blas - Cruisers & Sailing Forums

Well that's interesting..
In SasPlanet Yandex really low resolution, google not too much better, bing pretty good. Google high enough res to show it seems to tally well with bing. And navionics looks pretty close as well!

Bing with Lat/long from forum post and a temp marker.

Navionics>

Cmap>

So far SasPlanet is doing rather well

 

[Beneteau381]

Many thanks for taking the time to review my video. What can I say? I'm very much an amateur and trying my best! No, I've never used Powerpoint, and had nobody to submit my storyboard for review (Maybe ask you next time?). But this is the value of Youtube, it's the content rather than the professionalism of the production, with some very good instructional videos, and of course a lot of rubbish.

Myself and my family have also done the Day Skipper theory in Australia to get our ICC's, digital navigation was hardly mentioned. It depends who you get!

He seems to like using “big” words. You did good!