The Offshore Voyaging Reference Site

Tips For Receiving GRIBs


We now use an Iridium GO! with unlimited data for all weather product downloads including weatherfax, so most of what we do, and recommend, has changed from what I write about below.

That said, the system we detail in this chapter will still be of use to those who decide to stick with an Iridium handset without unlimited data, or an SSB radio with PACTOR modem.

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The GRIB charts are really useful, not only for the sailor but the recreational aviator (the next best thing to sailing!). Since you introduced the GRIBs on your website, I have used them to get an idea of the low/high areas and wind strengths as they approach Eastern Scotland. Helps in deciding when to fly during the coming week or at least have a chance of getting up in the air.

Dick Stevenson

I would want readers to be aware that all of the above functions (with the possible exception of advancing the boat along course – I will look into that cool function) can be accomplished through SSB connections. Sailmail is the commercial end with a very modest fee and deserves the support John suggested. Airmail/Winlink is the Amateur Radio (Ham) network, is free, has (within a reasonable cruiser’s needs) virtually unlimited download time, and has a huge array of weather downloads (such as weather faxes which often come through much clearer than a direct fax through SSB). With lots of download time (as opposed to Sailmail), download sizes are dictated by propagation quality and the proximity of good land stations. Virtually all my weather needs were met by Winlink for 8 years living aboard. The last couple years internet (Med & Atlantic coast) has become so accessible that the SSB is more relegated to offshore passage use. I have no experience in the very high latitude use of Sailmail/Airmail but there has only been a few days over all the years that I have been unable to get weather because of propagation or other problems. Regular use of SSB also keeps one competent in the event of an emergency. I would like to underline also the accomplishments of Stan Honey & Jim Corenman. It is volunteers such as these who put their minds to a problem that make the cruising community the wonder that it is.


We have been sailing the waters of Northern Norway since June 2011, wintering at 70°N. I am using Winlink/Airmail via my ham radio on a daily basis to download the GRIBs, get emails, and send our position reports with no problems. If I am not able to make contact right away (because of propagation or northern lights) I try again later in the day; it has always worked out so far to get the data, even though I always request the GRIBs for almost the whole northern Atlantic to see what’s coming. All at no cost, except a bit of electricity. Also, there are some very professional working sailing-nets run by ham operators who are happy to provide us with very detailed weather information.

Dick Stevenson

It has been 5 to 6 years since I sailed waters (Central America, Eastern Caribbean, Bahamas, U.S. East Coast) where a call to the USCG was likely to get a response but, when in those waters, once or twice a year I would put out a call on their emergency frequencies (4, 6, 8, 12 megs according to time of day and likely propagation) and I always got a nice polite response. Not carrying a sat phone, the USCG and the Ham Mobile Maritime net (manned many hours a day and monitored almost 24/7 by many Hams) were my 1st attempt at communication. Please note that in an emergency, non-Hams can use the Ham frequency without problem. If the CG has become as lax as you suspect, and I very much hope they have not, then the MM net would be my 1st choice. They are set up to handle emergencies and contact the CG.

BTW, the CG is not most easily contacted on 2 megs. As a safety channel it is relatively useless and this has been recognized for years. Probably a decade ago the CG started monitoring the freqs I mentioned earlier and those are where I reached them with ease. They monitor 2 of those 4 freqs 24/7, changing as propagation changes. I would share the specific freq numbers, but I am concerned about giving out safety data that I have not confirmed for years. They can be easily obtained on their web site.

Dick Stevenson

John, I will share another concern that spins off your reply. I have heard the same comments (among others) repeated by many who shy away from the learning curve of using SSB, marine or Ham, and head off shore with only a Sat Phone. They contend that SSB is outdated and all can be accomplished with a sat phone. Your supposition about the CG turning the volume down, if true, is lamentable and, if not true, may further push those on the fence to reject SSB. In many parts of the world, the best routing and weather data often comes from “amateurs” on SSB. The “party phone” aspects of developing and maintaining a wonderful feel in the cruising community should not be ignored as well as many other advantages to SSB competency.

gerard deroy

I have just tried your recommendation on the use of Saildocs and UUPlus tools to receive text, graphics and GRIB files. I do not have an Iridium 9555 yet. I just tested over the Internet. Everything works fine using only Saildocs or through UUPlus.
I am left with one question. For GRIB files, you mentioned that you sent your request directly to Saildocs instead of using UUPlus for efficiency sake. Is it for air time efficiency or easiness of the process? I hope I understood you correctly.

Geir Ove
Don Mitchell

I think an update is required for this as the availability of online weather and routing is much more prolific now. Any thoughts? I use several sites, from the local government weather sites to predict wind which also provides weather routing and weather charts and wind predictions live.


Wanted to throw out the possible combination of using a Sat phone plus a cheap SSB receiver like the Sony ICF-SW7600GR to at least keep up with chatter from nets. You can also use the receiver (and a cheap enhanced antenna) and the Black Cat app on the iPad/iPhone to receive NOAA weather fax. Never done it personally but I’ve seen others that have. For less than $200 (not including the iPhone) it’s an interesting option for getting offshore forecasts.

Charles Starke

Hi John:
I learned of a new development at the SSCA gam in Melbourne, Florida at the NOAA weather advisors’ booth. There is a new request available instead of GFS computer data. Substitute “NDFD” for “GFS” in your send request to saildocs and what returns is a Grib annotated by a meteorologist. Thus, we can now get interpreted Grib files instead of raw computer output. Only “|wind,waves” are available with NDFD.
This works well and is more reliable and interpretable than a computer GFS Grib. An example copied from your example above:
Send NDFD:36N,32N,052W,058W|0.5,0.5|6,9,12,15,18,24..72,84..168|WIND,waves|7.0,080

The latest airmail/sailmail program upgrade incorporates and makes available the NDFD request choice built into a drop down menu in the saildocs drop down menu for a Grib request. In the drop down menu within airmail, you can choose which computer model or interpreted NDFD file you wish to download.
I hope this helps!!! Try it!

Geir Ove

The price of installing and bying an SSB full pack is a lot more then getting an Iridium GO, and a pack at this is what we will use as we take off for the Carib 2016-17. and we can also use Saildoc ,Sailmail and dobbel up and compair.

Jim Kevern

Minor detail, GFS is now available in 0.25 degree resolution rather than 0.5 mentioned in the article. I mention this although the caveat elsewhere on these pages about increased resolution doesn’t necessarily mean more accurate results is still true. Some programs (I use RMS Express) don’t yet have 0.25 on the drop down menu, but it’s easy enough to edit the outgoing email to change that before sending.

Glen Doyon

When requesting a GRIB file ave you had any trouble receiving and viewing more than parameter using Luckgrib with a file requested through Saildocs and UUPlus? For me, for example, I can request this:
GFS:25N,16N,073W,061W|0.5,0.5|6,9,12,15,18,24..72,84..132|WIND|6.0,305 and I can get wind, and I can request this: GFS:25N,16N,073W,061W|0.5,0.5|6,9,12,15,18,24..72,84..132|WAVES|6.0,305, and get waves, but when I request this: GFS:25N,16N,073W,061W|0.5,0.5|6,9,12,15,18,24..72,84..132|WIND|WAVES|6.0,305, I only get the wind. I can see that there is a way to request a GRIB file through Luckgrib, and the Youtube video shows that you can get everything, but I haven’t tried that. Thanks for your help.

Glen Doyon

Figures it out. Syntax. I was using a vertical line between WIND and WAVES instead of a comma. Doh! Anyway….works fine now. Thanks. g

Bob McDowell

Good afternoon (a glorious day! The sun started back north just a few hours ago!)

I sail the European Atlantic coastal and offshore region on a normal basis and would like to get access to the ECMWF forecast model as it has been more accurate over the last few years. Can I access the model through saildocs or another ‘get’ system?


Bob McDowell

To clarify, I would like to use gribbed ECMWF data!


Ronnie Ricca

I am looking into PC navigation software (Timezero and Coastal Explorer) and was wondering why you don’t use the built-in grib/weather veiwer in Timezero that I believe you have? Wouldn’t that keep everything in one program plus being able to see your route under the weather data? If you’ve tried this already and either it doesn’t work well or you didn’t care for it, do you mind sharing your thoughts on this?

Thanks for this book as well, it’s great.


Ronnie Ricca

I have been re-reading this book and I was curious. To be clear, you have your Mac using Win10 for navigation then you boot to Mac, get your GRIB files, then view in Luckgrib, then boot back to Windows to navigate and also view the GRIB files in Timezero on another actical level with charts? Or do you use more than one laptop for this? I looked into Luckgrib and wish it was in Windows too because we have a MacBook pro with boot camp and it would save us from having to reboot to view gribs. Would you say the Timezero GRIB viewer is good enough for the job? Lastly, is your Timezero the new Navigator v3?


Terry Pimentel

this guide is fantastic but for some reason I can’t seem to get the command right. I copied/paste your example and it worked fine but when I changed the data to reflect my Bay of Biscay request….There was an error in the following command line:
(“|WIND,PRMSL,RAIN,HGT500|5.0,225” is not a valid command or document code).
who do I ask about what I am doing wrong here? thanks.

Terry Pimentel

Dear John,
Thanks for the suggestion. It took a while to figure out (not too tech savvy) but the plain txt seemed to do the trick. takes a little practice and careful attention as you’ve suggested. All the best.