Expedition Navigation Software 
1 of 1- nav
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Offline - Registered: 12/20/2015
- Posts: 91
Tidal Data for Fastnet
Hello,
With Fastnet approaching fast it's about time to get the sources for weather and tidal data sorted.
With a PredictWind Pro account there is access to the high resolution current data from Tidetech.
But the data from the Predictwind Current Grib seems to be shifted by 1hour compared to the Tidemap Data () from Tidetech:
Predictwind Current Grib at 0600 UTC:
Tidetech Tidemap at 0600 UTC:
Tidetech Tidemap at 0700 UTC:
The Predictwind Current Grib in Expedition from 0600UTC and the Tidetech Tidemap Data from 0700UTC look similar.
Anyone noticed the same?
Does anyone have both - a Tidetech and a Predcitwind Pro account - to compare the gribs?
Last Fastnet even higher resolution grib files were available through Tidetech:
Haven't heard yet if they will do the same this year again.
- DuncanR
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- From: Up and down East Coast Aus
- Registered: 9/16/2015
- Posts: 471
Re: Tidal Data for Fastnet
- sparky
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- From: Cambridge UK
- Registered: 4/27/2018
- Posts: 247
Re: Tidal Data for Fastnet
Related question --- I don't see anything in the NOR and any of the RORC documents. Is Rule 41(c) modified to allowed paid weather/tide sources?
- Nick
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Re: Tidal Data for Fastnet
Tidal currents are ok as you you download them before the start.
- sparky
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- Registered: 4/27/2018
- Posts: 247
Re: Tidal Data for Fastnet
Nick wrote:
Tidal currents are ok as you you download them before the start.
With that in mind who has a current model that will last for a 5 day race?
Looks like only the Mercator current model goes long enough (MyOcean doesn't) and Tidetech might.
Last edited by sparky (7/20/2019 3:43 pm)
- nav
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- Posts: 91
Re: Tidal Data for Fastnet
As I understand it is the "High Resolution Tidal Currents" in the PW Offshore app.
I can download a file there called 'High-Res_Tidal_Currents_62N_48S_10E_-12W_northwest-european-shelf-currents' -unzipped about 250MB- that covers a large area between Iceland, France, Denmark in 1-hour-steps for seven days.
I did not find the ultra high resolution model fro the Solent from TideTech in PredictWind, so they don't seem to make alle TT models available with a PW Pro account.
Last edited by nav (7/22/2019 3:05 am)
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Thread Starter- DuncanR
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- From: Up and down East Coast Aus
- Registered: 9/16/2015
- Posts: 471
Re: Tidal Data for Fastnet
Nav, well found. I have found very significant differences between Hi-Res and TideTech in certain areas (e.g. Queensland coast inside the reef), I suspect because they are not covered by the Hi-Res model in the way described in that PW note.
- DuncanR
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- From: Up and down East Coast Aus
- Registered: 9/16/2015
- Posts: 471
Re: Tidal Data for Fastnet
Nav, well found. I have found very significant differences between Hi-Res and TideTech in certain areas (e.g. Queensland coast inside the reef, where tidal influences are very significant), I suspect because they are not covered by the Hi-Res model in the way described in that PW note.
- DGS
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Re: Tidal Data for Fastnet
From RORC NOR 2019 pt1 which applies to the Fastnet Race 2019
1.11.1 RRS 41 – OUTSIDE HELP Rule 41(c) is replaced by: “A boat shall not receive help from any outside source, except (c) help in the form of information which is freely available to all boats, which shall include navigational, weather, tide or current information from any source which is available to all boats whether or not by payment of a fee or subscription, but shall not include any information gathered or the subject of interpretation by, or any advice received from, any source not on board the boat and which is specific to the boat and her situation.”
By way of example and interpretation: downloading charts, weather and/or tidal GRIB files from subscription services, or having such information passed to the boat in its pure form, is permitted but receiving messages or information which is the result of interpretation as it applies to the boat is not permitted.
Last edited by DGS (8/01/2019 1:02 am)
- sparky
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- Registered: 4/27/2018
- Posts: 247
Re: Tidal Data for Fastnet
From RORC NOR 2019 pt1 which applies to the Fastnet Race 2019
1.11.1 RRS 41 – OUTSIDE HELP Rule 41(c) is replaced by: “A boat shall not receive help from any outside source, except (c) help in the form of information which is freely available to all boats, which shall include navigational, weather, tide or current information from any source which is available to all boats whether or not by payment of a fee or subscription, but shall not include any information gathered or the subject of interpretation by, or any advice received from, any source not on board the boat and which is specific to the boat and her situation.”
By way of example and interpretation: downloading charts, weather and/or tidal GRIB files from subscription services, or having such information passed to the boat in its pure form, is permitted but receiving messages or information which is the result of interpretation as it applies to the boat is not permitted.
Awesome -- glad it was just something I missed.