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Old 09-08-2016, 16:08   #1
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Cannot see Tidal Stream for English Channel

Hi, Been trying out OCPN v4.2 for a while. No tidal streams shown for English Channel, also very few Tidal Diamonds shown, unlike Belgium to Denmark which has many. Streams can be strong in E.C., especially complex in area of Channel Islands. The 2 icons, Tides & Streams shown Green. I updated to OCPN v 4.4 but no different. How do I get Tidal Steams to show for English Channel ? Help mentions 'This is important when you have multiple sources covering the same area.' -implying OCPN works with multiple tide databases. But where do I find any tide databases for E.C. ? Default installation has only HARMONIC.IDX in Options>Tides & Currents. Is OCPN able to read the annual SeaPro Tide database file ?

Also, to avoid need to use browser, where can I find a current Help.PDF ? Saw one for a v. old ver of OCPN.

Thanks.
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Old 09-08-2016, 17:10   #2
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Re: Cannot see Tidal Stream for English Channel

Believe it or not, there is a lot of information here.
OpenCPN User Manual | Official OpenCPN Homepage
You might take a look around, maybe do some searches?

Tides and Currents | Official OpenCPN Homepage
External Plugins | Official OpenCPN Homepage
Tides | Official OpenCPN Homepage

Also there is a fellow who has started a plugin

https://github.com/registry/admiralty_tide_tables_pi

I've tried to help by building for windows and testing, but this is still a work in process.

Here is another source http://noc.ac.uk/using-science/products
Can't find the harmonics files anymore.
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Old 09-08-2016, 17:18   #3
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Re: Cannot see Tidal Stream for English Channel

Still can't find UK harmonics, but VisitmyHarbor might help
visitMyHarbour.com Articles

This works too I think
http://www.ukho.gov.uk/EASYTIDE/Easy...electPort.aspx
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Old 10-08-2016, 07:48   #4
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Re: Cannot see Tidal Stream for English Channel

Many thanks for your suggestions. However, I thought it was evident from my post I had read the 'Official OpenCPN User Manual' on the topic, from my "Help mentions 'This is important when you have multiple sources covering the same area.' -implying OCPN works with multiple tide databases." This text is a quote from the 2nd link in your post, taken from just below the harmonic graph. My post prefixed the quote by 'Help mentions' as the User Manual appears to be easily accessed only via the 'Help' button when running the program, hence my secondary question, is there an uptodate PDF version (preferably with the same internal hyperlinks)

Regarding your first suggestion, a link to the OpenCPN User Manual, as with the above reference to Tides, it should be obvious I had a good look through the manual before posting my question.
Your 3rd link, to External Plugins in the OCPN Manual. I was led to believe from the 'Tides and currents' section in the Manual, display of Tidal Streams is integral to the program, not requiring a Plugin. However, I did scan your link but found no plugin to show Tidal Streams

Your 4th link refers mainly to non OCPN items. The 1 item that refers to the default HARMONI.IDX has a dead link

I read through most of the readables in your 5th link, but as you say, guess not yet ready for use.

Your 6th and final link in your first post, from what I could find, refers to non-OCPN commercial products.

So having perused all of that, it occurs to me I may not have been sufficiently clear explaining what I am seeking: I want to see Tidal Stream arrows on the chart that is displayed in OpenCPN, preferably with Direction in Degrees, and Strength in Knots (with auto-decluttering), either shown next to the arrow, or quickly viewable by right-clicking on the arrow.

Perhaps I should have added that when I lived continuously on the UK South Coast partaking in many yacht races across the Channel to France, Previously dependant on local tidal Stream paper Atlas's, from the early/mid 90's, I used 'PC Wayplanner' type programs, finally investing in the'SeapPro200' program using the separately purchasable detailed vector 'LiveCharts B'. As Navigator, I used both the electronic tidal stream prediction displayed on the chart by SeaPro, which used those predictions to calculate the CTS (Course-to-Steer) for each leg of the Route, using internal iteration along each leg ETA to produce a final ideal CTS/leg (the version in 1999 not acounting for other factors like wind). The way SeaPro implemented the source tidal stream data, was to embed MANY Tidal Diamonds in EACH LiveChart at key positions (over 1,000 diamonds for English Channel) in order to build an accurate model of how streams varied around headlands, eddies/counter-currents etc. In conjunction with the Diamonds embedded in each Chart, they publish a free Tidal Data file for the English Channel each year, lasting 1 Year.

As OpenCPN can work with many Chart Types, I assume from the Manual it relies entirely on self-contained tidal database's compiled for each chart area. A problem with the default HARMONIC.IDX installed into OCPN is it has only 4 Tidal Diamonds for the Central English Channel, not one from Belgium to Gibralter, and only a single Diamond for the strong complex streams in the Channel Islands. When zooming out globally, the USA shows many orange diamonds referred to in the 'Tides and Currents section of the Manual, but none for Europe, Africa, Asia, S. America. Is that, in fact, the explanation why no Tidal Streams show for English Channel ?

I had assumed the default HARMONIC.IDX was intended to cover most of the world's main sailing areas, but the almost complete absence of orange diamonds outside the USA, I think supports my thoughts in my original post, separate Tide Database files, compatible with OCPN, are required for each sailing area outside the US, for Tidal Streams to work.

So it looks like the primary question from my original post is WHERE can I DOWNLOAD a suitably detailed data file that OCPN can use to show Tidal Streams in the English Channel ?

Does OCPN use the tidal stream model in its computation of CTS for each leg of a Route ?

Reason I am interested in OCPN, is not had chance to sail in the English Channel last 10 years, and told my SeaPro investment u/s due to need to upgrade an expensive hardware protection dongle and newer software. I have only a 2 month window for more sailing in UK, so not worth paying to make SeaPro usable again, and likely by next window, will again be u/s without buying upgrade. Another reason I like other Open-Source, eg Libre-Office, Inkscape.
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Old 10-08-2016, 08:10   #5
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Re: Cannot see Tidal Stream for English Channel

Quote:
Originally Posted by paul2 View Post
So it looks like the primary question from my original post is WHERE can I DOWNLOAD a suitably detailed data file that OCPN can use to show Tidal Streams in the English Channel ?
There used to be a harmonix file from a French forum with admiralty data hand copied into it, maybe google would find it.
Pretty sure the reason tidal streams aren't available is because our lovely UK system means you have to pay for the data, it ain't free like the US and doesn't exist as harmonix files.
(I'd be very happy to be proved wrong )

I spend some time using GE2KAP top convert tidal stream atlas page images into charts, works quite well but it is a fair bit of work.

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Old 10-08-2016, 10:56   #6
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Re: Cannot see Tidal Stream for English Channel

This is a screenshot of the Channel with activated tidal currents from a Harmonics V9 file compiled by some french people. Have a search with Google for "Harmonics V9" and unpack it to your UserTCData folder. Go to OpenCPN options/charts label tides and currents and insert/activate the supplemental Harmonics file in the list.

Gerhard
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Old 10-08-2016, 15:03   #7
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Re: Cannot see Tidal Stream for English Channel

Carcode, Conachair, thank you. I am guessing that paul2 wants the most current V10 found here
Martine, Pierre et leur voilier Logos

Paul2, since I've annoyed you enough to spout on about our inadequacies, perhaps you would take a bit of that vacation time and devote it to helping out, either with programming or improving the documentation on Tides?

Just keep in mind this is a "volunteer" effort by everyone.
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Old 19-08-2016, 03:52   #8
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Re: Cannot see Tidal Stream for English Channel

Many thanks for your comments and helpful pointer to the french with 'Harmonics V9'. Googling Harmonic V9 brings up many hits, but only the 1st hit appears relevant:
Martine, Pierre et leur voilier Logos It also contained a 'V10' much smaller than the V9 so ignored. Although the Help manual states works with multiple tide files, to be sure I moved the default file and installed the new.

Overview of French Harmonics V9:
It has large number of Tidal Diamonds (green icons) for Tidal Height from Norway down through Br. Isles, Iberia, whole of Africa, mid-Atlantic isles, most of Caribbean, E. coast of S. America.
Tidal Streams (orange icons) cover an area from Holland, English South coast central section, down to southern end of France-Atlantic, with the highest resolution along Dutch and French coasts down to Arcachon

Zooming to central section of E.C. UK side, I see 2 extra 'Stations' Shoreham & Southampton. See a small sprinkling of Stream Diamonds (orange): 3 in Solent (Hurst, Cowes, off Bembridge), 1 off Old Harry, 1 off Portland, 1 abt 20M S of Christchurch, 1 5M S of St. Catherines.

Clearly a huge improvement over no streams at all, but just 3 stream indicators for whole of the Solent, and a sprinkling of streams in rest of the central section of the E.C. gives only a rough indication sufficient for cruising, not for racing. Stream resolution for French coast and the complex streams of the Channel Isles appears very useful, comparable to stream resolution shown by SeaPro and approaching that of local paper Tidal Atlases for most areas excepting Baie de Seine with only 4 orange streams from Isigny to Dieppe. It follows the complex tides in Seine Estuary not modelled.

Re. my question does OCPN use tides in Route Planning & CTS, it appears not. I briefly made a 5.0nm 5kt identical Latitude East-West test route between Alderney and Cap de la Hague when the race was running South 8 knots. The Route Properties showed ETA 1hr, CTS 271mag. Had tidal stream been taken into account, CTS would have a large northerly offset & ETA far longer than 1hr. Looking back through OCPN history I see initially it did not have any form of tidal Streams so the Route Planning module may not have been designed to allow future use of a tidal stream module to link into its calculations

SeaPro uses small ~300KB tidal files covering 1 year, as opposed to the 2.37MB French V9 file dated 2013. Don't know if that is due to differing area and/or differing time coverage.

I have not looked into 'harmonics' method, or if it is different to that used by SeaPro which has plenty of stream indicators comparable to the resolution given by traditional Tidal Atlas's. Paper Atlas's like Reeve-Fowkes covering Central E.C. and detailed paper Atlas's published by the likes of Peter Bruce, use actual observations of inshore tides taken by local fishermen going back to before WW2, show where/when counter-currents occur. I suspect it may require a different model to provide that resolution.

And yes, I agree UKHO is behind the restricted info on tides in the E.C. I remember when SeaPro first launched it had more detailed stream resolution, which was later reduced. When I asked why, told ordered to by UKHO as they had the copyright. I read UKHO would rather see boats sink than be given full tidal data ! Thanks again for your helpful input.
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Old 19-08-2016, 03:58   #9
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Re: Cannot see Tidal Stream for English Channel

@rgleason By time of your reply I had already followed up on Carcode & Conahair's reply and only read yours the other day when I logged in to thank them and post my results. I saw the 'HARMONICS V10' in the same folder, but as its size much smaller than the V9, with no description and Carcode recommending I use V9, that is what I tried. When I next get chance to play with OCPN I will try the V10.

Regarding your comment on having annoyed me and spouting on; well yes, you accused me of not having read the manual, but had you read my post carefully, I was quoting (in quotes to be abosulutely clear) from the very section of the manual you referred me to !
My reply was more time-consuming than I wanted due to content of your reply as all extensive links your first reply directed me to, turned out to have no bearing on how to get OCPN to show Tidal Streams for the English Channel, I felt obliged to read all of your links before replying your posts had not answered my question. Sorry you thought that was spouting. I dont doubt your replies intended to be helpful, but for a relative newcomer to the site, I thought your mention of 'our shortcomings' inhibiting of further questions, as unwelcome - not that that was my intention, for someone living outside the US I merely asked where the Tidal Streams were. (I realise electronic encoding of Streams for the world is a mammoth task, but as it had already been done for the E.C. I thought having done everything the Manual said, it would show on OCPN). I did have a further question and suggestion on the topic of Chart Zooming. May put that after gaining more familiarity with OCPN during my next sailing window.

I am aware of the difference between commercial and open-software; prior to PC's being common I contributed to open-software. However, as should be apparent from my initial post, I am new to OCPN (I registered in 2010, but as stated in last post, been out of sailing for last 10 years), programming experience long outdated, and as alluded to in last post, had only a 2 month window for sailing. I now have time for just 1 trip across the Channel, next opportunity being 2 years ahead. So I hope my findings above may help input into this most welcome project, both in documentation, and for the Route Planning software.
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Old 19-08-2016, 04:30   #10
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Re: Cannot see Tidal Stream for English Channel

@carcode, @conachair Many thanks for your comments and helpful pointer to the french with 'Harmonics V9'. Googling Harmonic V9 brings up many hits, but only the 1st hit appears relevant:
Martine, Pierre et leur voilier Logos It also contained a 'V10' much smaller than the V9 so ignored. Although the Help manual states works with multiple tide files, to be sure I moved the default file and installed the new.

Overview of French Harmonics V9:
It has large number of Tidal Diamonds (green icons) for Tidal Height from Norway down through Br. Isles, Iberia, whole of Africa, mid-Atlantic isles, most of Caribbean, E. coast of S. America.
Tidal Streams (orange icons) cover an area from Holland, English South coast central section, down to southern end of France-Atlantic, with the highest resolution along Dutch and French coasts down to Arcachon

Zooming to central section of E.C. UK side, I see 2 extra 'Stations' Shoreham & Southampton. See a small sprinkling of Stream Diamonds (orange): 3 in Solent (Hurst, Cowes, off Bembridge), 1 off Old Harry, 1 off Portland, 1 abt 20M S of Christchurch, 1 5M S of St. Catherines.

Clearly a huge improvement over no streams at all, but just 3 stream indicators for whole of the Solent, and a sprinkling of streams in rest of the central section of the E.C. gives only a rough indication sufficient for cruising, not for racing. Stream resolution for French coast and the complex streams of the Channel Isles appears very useful, comparable to stream resolution shown by SeaPro and approaching that of local paper Tidal Atlases for most areas excepting Baie de Seine with only 4 orange streams from Isigny to Dieppe. It follows the complex tides in Seine Estuary not modelled.

Re. my question does OCPN use tides in Route Planning & CTS, it appears not. I briefly made a 5.0nm 5kt identical Latitude East-West test route between Alderney and Cap de la Hague when the race was running South 8 knots. The Route Properties showed ETA 1hr, CTS 271mag. Had tidal stream been taken into account, CTS would have a large northerly offset & ETA far longer than 1hr. Looking back through OCPN history I see initially it did not have any form of tidal Streams so the Route Planning module may not have been designed to allow future use of a tidal stream module to link into its calculations

SeaPro uses small ~300KB tidal files covering 1 year, as opposed to the 2.37MB French V9 file dated 2013. Don't know if that is due to differing area and/or differing time coverage.

I have not looked into 'harmonics' method, or if it is different to that used by SeaPro which has plenty of stream indicators comparable to the resolution given by traditional Tidal Atlas's. Paper Atlas's like Reeve-Fowkes covering Central E.C. and detailed paper Atlas's published by the likes of Peter Bruce, use actual observations of inshore tides taken by local fishermen going back to before WW2, show where/when counter-currents occur. I suspect it may require a different model to provide that resolution.

And yes, I agree UKHO is behind the restricted info on tides in the E.C. I remember when SeaPro first launched it had more detailed stream resolution, which was later reduced. When I asked why, told ordered to by UKHO as they had the copyright. I read UKHO would rather see boats sink than be given full tidal data ! Thanks again for your helpful input.
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Old 19-08-2016, 06:21   #11
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Re: Cannot see Tidal Stream for English Channel

Paul I have made mamy points from Bishop's to the Baltic entrance, although it is not perfect it give a general idea of the current over times, specially using the OT Current Plugins. Most of them were coming from the old Tidal atlas. If you are interested you ca have a copy to enter in the tc data sub-directory of OpenCpn and replace what is included. It was a lot of work and is working fine
using the correct time zone of each country.
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Old 19-08-2016, 06:35   #12
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Re: Cannot see Tidal Stream for English Channel

Quote:
Originally Posted by paul2 View Post
And yes, I agree UKHO is behind the restricted info on tides in the E.C. I remember when SeaPro first launched it had more detailed stream resolution, which was later reduced. When I asked why, told ordered to by UKHO as they had the copyright. I read UKHO would rather see boats sink than be given full tidal data ! Thanks again for your helpful input.
Paul2,
yes, it is strange they want to be paid again for data which has been paid already by the taxes of the british people. But as Britain wants to leave the european union also they have obviously another mind than others.

Gerhard
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Old 19-08-2016, 08:31   #13
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Re: Cannot see Tidal Stream for English Channel

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Originally Posted by P_Dub View Post
Paul I have ... specially using the OT Current Plugins. Most of them were coming from the old Tidal atlas. If you are interested you ca have a copy to enter in the tc data sub-directory of OpenCpn and replace what is included. ...
Thanks, I had a peek at your embedded .JPG and at first glance the qty of streams looks similar to the Harmonics V9. Reason I picked Alderney Race to test if the Route Planning took Streams into account, was a) that area has stong Streams, 8Kts in that example, and because the French file had 2 orange stream icons between Alderney & Cap de la Hague.

Yes, would like a copy of your data file to try out thanks.

You mention 'OT Current Plugins' & 'old Tidal atlas' - can you elaborate ?

Do you know if there is a way of determining the expiry date of HARMONICS files ? (I briefly perused the quite readable main file & its .IDX, in Notepad but didn't see an expiry date) I am guessing each HARMONIC file is valid for only a limited set of years ?

Might 'OT Current Plugins' allow for non-Harmonic methods of potentially more accurate modelling - and the all-important displaying of Streams on OCPN charts ?

If designing a non-Harmonic method of encoding and displaying tidal Streams for OCPN, a simple route may be to encode the approx Lat/Long of each Stream marker from a good old paper atlas, then encode the Strength/Direction data pairs for each hour of tide ref to the Reference Port - ideally Cherbourg for central section of E.C., then design an engine to :
a) every minute or so, cycle round each Stream Marker within the displayed Chart area, and overlay the chart with the Strength/Direction (with suitable declutter) for the current time, as interpolated between the pair of encompassing hourly reference data rows, and
b) use a similar technique to iteratively build ETA & CTS segments of the Route, using datasets from the nearest Stream Markers closest to rhumbline of each route segment. The ETA/CTS could be run just when creating/editing the Route for static result, or selected to update every 10 minutes or so when under way, depending on duration of Route-Segment or a user setting.
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Old 19-08-2016, 09:07   #14
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Re: Cannot see Tidal Stream for English Channel

I don't know where they have their data from. But an interesting site is
Tides 4 fishing for Brighton, England in 2016 (example Brighton) however mostly tidal data but no currents data.

Gerhard
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Old 19-08-2016, 09:43   #15
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Re: Cannot see Tidal Stream for English Channel

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Originally Posted by CarCode View Post
I don't know where they have their data from. But an interesting site is
Tides 4 fishing for Brighton, England in 2016 (example Brighton) however mostly tidal data but no currents data.

Gerhard
Thanks for your link. Very good at a glance current tide and moon/sun data. Perhaps too much to expect them to link to tidal stream sources. I read from Peter Bruce books and internet posts fishermen also need to know strength of inshore streams, and thus have much archived observations collected many decades ago. I remember reading about a French Tidal Atlas produced for Baie de Sein with very high resolution streams, that was very accurate until they built a training bank in the Sein Estuary, which of course disturbed the flow.

Do you know the validity dates for the 2013 dated French V9 file ?
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