Weather Data Additions

Hi there,

being a sailor, I am predominantly interested in the grib files coming down via the data stream.
What could be added are several weather fax maps which are available via RTTY on short wave, or long wave and also on the web pages of the weather services which create those maps.

For example NOAA in the US or the UK MetOffice, or the DWD in germany. Many other weather services exist.

It would be sufficient to get only the weather maps which cover the same sea area which the respective inmarsat satellites cover.

This would be sufficient for the grib files too. Only send the information for the respective satellite and a lite bit over the edges of the reception are. The saved amount of downstream could be used to extend the time frame of the predictions to lest say 5 or 6 day. After that predictions get unreliable anyway.

Best regards.



Could you please give me some example links to the specific images, and tell me a bit more about what would make a complete set to be useful? I have been wanting a practical tutorial on those images for some time now.

Also, are the current grib files useful at all? If you are using them (even just as a trial), could you tell me how - which viewer software you are using, whats your client setup (device, os), etc.

This is very useful even for land lovers, they often cover lots of land in predications… in the south east our weather fax stations cover the gulf as well as much of the gulf states, so we use it when out of coverage for other services…

Here is the noaa landing page for weather fax.

Here is an example of a weather fax in gif…

Hallo AbhishekG,
this would be NOAA in the USA NW Atlantic.
This would be the UK MetOffice.

To the leisure mariner only the prediction for the area he is located is of interest. So if one wanted to could only send the data for the atlantic the meditaranien sea north sea and baltic sea from the inmarsat satelity which covers that area.

Mariners are as every human they use what they are used to. People from the UK us the UK maps. The americans use the NOAA stuff and the germans usually the DWD stuff.
Most of the other countries produce their own weather maps. Would be kind of hard to collect and stream them all.
And redundant since one only needs one good prediction.

The entire forecast time should be broadcasted.
The upper air charts for example are of no particular use so I would not send them.

I have not received my outernet equipment jet so I do not know how the grib resolution is and what data is being sent.
In general you can say that getting some information is better than getting no information.

Right now at sea you can use NAVTEX massages which have some weather information but this is only within 300nm of the coast.
VHF gives some info 30nm of the coats.
Than you have standard SW, AM or FM radio with thair respective ranges.
Inmarsat savetynet gives some weather information. But usually it is of this nature

This is vital stuff in a short format.
So no maps.

qtVlm is the program I use to do weather routing. In a nut shell. I feed it with the grib files and tell it from which point I want to go to which destination. It that calculates the rout which gets me there in the shortest amount of time. This usually means that I do not take the shortest rout because that is usually not the fastest.

ZyGrib is another program I use to what the grib files.

Both programs can overlay analysis maps ( I linked to above) onto the grib data. This way one can compare grib data which is raw computer output with what a real meteorologist has to say about it.

Using all of this and combining it with what I can sea and measure (wind speed, temperature of the air, air pressure and humidity) hight of waves etc gives a prety good understanding of where I am in the weather system and what I have to expect and where I should be going.

Due to the low price of the outernet equipment a huge improvement to the weather information yachtsmen have on rout to their destination can be achieved.
Not in coastal waters but as soon as one leaves more than 30nm offshore right nor moast yachts do not get new weather information.

With outer net this would be possible and could easily save lives.

Feel free to contact me any time if you have further questions.

Best regards.

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Thanks, @BenFranklinIII! This is very helpfull. Let me spend some time getting into the details and then I will probably have more questions.

As another sailor - I can say this would have endless potential/use for us. Subscribing to a crazy satellite data plan to receive very simple information isn’t an option for many - WeFax keeps us relatively safe, and for the enthusiasts, there’s APT/LRPT from the NOAA sats, but the average person isn’t really familiar with this space.

Adding a few more elements to the data provided for sailors would be great. GRIB data already included is invaluable - I wonder if there’s a light format of raw data that can be interpreted for the charts Ben mentions? Sending an image would be quite large, where space is a commodity.


I toyed around with zyGrib and made a minimum grib.

For the AOR-E Satellite I would use Grib data from 90N to 90S and 90W and 60E.

The Data I would use are:Wind, Wind gusts, Air Pressure, Cloud cover, Precipitation and significant wave hight global coverage 1x1°.

All the weather data would be for 1x1° 6 hour intervals for 4 days.

After 4 days predictions becom unreliable any way. 4 days schould be sufficient to make safety related decisions for a safe journey. To plan ocean crossings one can use shore based internet excess and 10 day grib files.

They data volume is 3,4 MB. If this would be supplemented with weather charts for the north mid and south athlantik plus north see med and baltik one would be somewere arround 6 MB. Almost 1/3 of the entire data volume Outernet can send in a day.
A good compromise could be to send the grib an an odd day and the maps on an even day.
This should still be sufficient to keep a leisure sailor safe.

Best regards.


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Brilliant. I’d agree with that. Outernet would go from an optionally awesome companion, to an absolute must. Not that there’d be any implied reliability of service/liability - but it’d certainly make this a preferred tool for cruisers.

I have come up with one last addition.

The NOAA and the Weather service of brazil offer IAC feet code data files.
They can be viewed with zygrib or opencpn which can laso display grib files.

Unfortunately the area covered is only the east Atlantic.
The advantage of the fleet code is that fronts and everything else on a weather map can be show with a very smal amount of data space. Usually around 10KB.

Would the NOAA or another weather service offer a similar compact way of delivering weather data one could easily fit the gfs grib and real human predictions into 4MB per ocean region.

To me more would not be necessary.

Best regards.

Benjamin Bergmann

On the weather app. I can zoom or move in to a point on the globe projections with a mouse double click.

Has anyone found a way to zoom back out ? Or is there a keyboard command ?

Have you tried using the “mouse wheel”? It seems to work well for me both zooming in and out…

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