openCPN UK Tidal Streams and Charts

[sparticle]

As a long time user of openCPN in various flavours and a regular sailboat user on the North Sea and the East coast of the UK.

Having reliable tidal stream data on screen would be a massive help. I have read many threads on here and elsewhere. The harmonic files seem to be ancient and provide coverage from the Humber south and across to NL but nothing North of the Humber we can find.

qtVlm shows tidal stream information from a loaded grib2 file it seems and we can request it when configuring the grib request.

We currently seem to be caught between the 2 programs. To run both at once requires a lot of horsepower something we can't reliable do at present and are trying to avoid as it brings significant power usage with it.

We also cannot get raster charts on openCPN for the UK at any reasonable cost. We can get great officially derived osenc charts but unless we are missing something do not contain any tidal stream information.

In qtVlm we can get great UK and NEar Europe officially derived raster charts that mirror the paper charts at reasonable cost £30.00 but no ENC's apart from chartworld which no one can consider 'reasonable cost' for a leisure sailor for the same coverage would be many hundreds of pounds.

On our modest hardware. We have tried rpi3/4 and are currently using a 12v mini-pc with 4GB ram and solid state disk running Ubuntu 18.04.5 since 2019. Considering going to a rpi4 8GB unit.

We only want to use officially derived charts and would love to be able to use a single program for both raster and ENC charts. I have asked Steve at visit myharbour why he cannot allow his raster charts to be used on openCPN linux as he does for openCPN windows and his unified charts.

What do others use. We have no interest in CM93 hacked charts or other dodgy chart sources. We are happy to pay for charts within reason. The c. £30 for ENC's and £30 for Raster cahrts seems reasonable to us.

But we can't use them in a single program. And tidal stream info seems to be a black art. Are there plans to incorporate official tidal stream diamond tables into openCPN as published on the Raster Charts?

As we have the ships realtime data, position, STW, SOG COG HDG etc. One would think this would be a relatively simple calculation with reference to the tidal diamond tables. But, I am not a developer!

We can all see the dynamic effects in realtime on board HDG vs COG STW vs SOG etc. A bit late then, it would be great to have this information at the planning stage when plotting a route. CTS calculations could also be made and presented with this information.

What do others think. These are all the things we do/have to think about when sailing in the very (sometimes extreme) tidal waters around the UK coast.

e.g. Try getting out of the river humber when the tide is in full flow on a sailboat that generally does 6kts in good conditions and you will be going backwards!

Being able to see and use the tidal stream information when planning would be very useful I would have thought to anyone using openCPN in the real world.

Anyway this may be already possible and we have missed something along the way.

Cheers
Spart

[Rasbats]

Sailing Weather Online

Is a fantastic resource for tidal current gribs. I used FileZilla to download the North Sea gribs

Mike

[sparticle]

Originally Posted by Rasbats

Sailing Weather Online

Is a fantastic resource for tidal current gribs. I used FileZilla to download the North Sea gribs

Mike

Hey, thank you for this Mike, very useful. I found it easier to get directly from the German site as we don't use ftp and none of the links would provide a download file.

The URL is: https://filebox.bsh.de/index.php/s/Z...rib2%2FNordsee

You can download the 3 day gribs from that directory via a web page. The .bz2 compressed ones open fine in the grib plugin once downloaded.

e.g. https://filebox.bsh.de/index.php/s/Z...00_00.grb2.bz2

The day1 (today) North Sea area current grib. With numbers switched on it is a great visual ref of the way the current flows up and down the coast.

Cheers
Spart