Marine weather by satellite
Marine weather on a map, on your Garmin inReach.
On its own, an inReach only sends short text messages: it can't download a forecast. reChain fixes that. Send a weather request, get a real GRIB file back by satellite within minutes, and view it on your phone with the free reChain Grib app.
3 free requests every month, no account needed. Need more? Go unlimited for €9/month · Manage my subscription
09:42
GFS:45.00N,38.50N,2.25E,12.75E|1.3,2.1|6,12,18,24,30,36,42,48|WIND
✓ Sent via satellite
GRIB received · 41 KB · zlib + base64
09:47
msg 1/12:
pTyGJMuHbEL31IeL2HPcHyGcFRl1SPnXNYvMIHa/2o76umfXfKm/r5…
end
msg 2/12:
kJP1VrT+1FJors/6ILi8IHn5kxsC7tVO/HbkQfyy/KV5zjR3j1twdT…
end
msg 3/12:
KWTddB+XhkAS1voQG6yyzyN9zHYIa4UOrGNATMuDJawTgsu8PO+799…
end
msg 4/12:
nKSNrh9UCauSDmLhuVtcqcYezdZ/tDDj8hYs5suKcNd8Zra9A9sKPx…
end
msg 5/12:
Z9W3qLy7zKUVQDT7S8sTQCBNR3YbDgbleph1QHt61QTC4XATWS8PHp…
end
msg 6/12:
9NHfYjFM5DI4pZj59fhZ5R1Py4oJe2JbmPTuSgR7cMy+UcU3zr1Zto…
end
msg 7/12:
LuCr64CxqlIOdNKhiFXiQ2hzT/pLjHX2JiCLhKcIhP6Br1iQFeOUhG…
end
msg 8/12:
XZnnal5WisCgEBCY8f5N3/ynbdrZRzsGQBJg3UHKwkflF6XUi5Ahuq…
end
msg 9/12:
pfEnbtXAqwK8jZfALhLSzFyCmmdKTxp/TkSF2RCdKDFRuNw5GCf+hA…
end
msg 10/12:
6ILI8gJhead6/wJ9kFZJSqgmRB9H+iMb+lk777PZnK8Cl6J5ixaaJL…
end
msg 11/12:
ShuQjOud/+yDUA+5zmS1swoPqApryPZBlgvIyxJu2jGjNGkTfi3oYv…
end
msg 12/12:
2DzaKG05Rk+GQV81rkmghzem9yPVUJa/c5q52RYfLWrLoevhZC0x0a…
end
How it works
Send a request. Get a GRIB back.
Three steps, a few minutes. Only short text messages travel by satellite; everything else happens on your phone, offline.
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Draw your area
In the free reChain Grib app, draw a rectangle on the map and pick GFS or ECMWF, the forecast range and the data. The app writes the request for you:
GFS:48.00N,28.00N,45.00W,15.00W|1.0,1.0|6,12,18,24|WIND -
Send it from your inReach
Paste the request into a message to jcskipper.rechain@gmail.com and send it, like any other inReach message. No pairing, no account.
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Get the GRIB back
Within minutes, the forecast arrives as a few short messages. Paste them into the app: it rebuilds the GRIB file and shows wind, pressure and waves on an offline map.
Already use Saildocs? Any request starting with gfs: or ecmwf: works; the app simply builds it for you.
What you get
Real GRIB files, from the models routers use.
Not a line of text for a single point: a full forecast grid over your area, hour by hour.
Wind
Speed and direction from GFS or ECMWF, to choose your route and time your departure.
Pressure & isobars
Sea-level pressure to spot lows, fronts and calms before they reach you.
Waves
Significant wave height, to know what sea is waiting for you offshore.
Up to 7 days ahead
Forecast steps from 6 hours to 7 days, at the resolution you choose.
Offline wind map
Animated wind, isobars and wind speed with a tap, with no internet on board.
Your routing software
Export as GRIB1 or GRIB2 and open it in qtVlm, OpenCPN, Expedition or Adrena.
Built for inReach
Works with the inReach you already carry.
reChain sends real GRIB weather files to a Garmin inReach. An inReach can't download files: each message is limited to 160 characters. reChain fetches your forecast from Saildocs on shore, compresses it and sends it back as ordinary satellite messages that your inReach receives natively.
- No new hardware, no device mod: just add an email contact.
- No pairing and no account to start: 3 requests are free every month.
- Works anywhere your inReach has satellite coverage: mid-ocean, off-grid, no Wi‑Fi.
- Also works with ZOLEO.
- Works with
- Garmin inReach devices that can message an email address (inReach Mini 3 Plus, inReach Mini 2, inReach Messenger Plus, inReach Messenger, GPSMAP 67i, Montana 700i…) and ZOLEO.
- Weather models
- GFS (NOAA) and ECMWF, via Saildocs
- Data
- Wind, sea-level pressure (isobars) and waves, up to 7 days ahead
- Delivery time
- Usually a few minutes
- Satellite messages
- About 7 to 20 per GRIB; the app shows the estimate before you send
- Price
- 3 free requests per month, then €9/month for unlimited use
The reChain Grib app
GRIB weather, from request to wind map.
Real screenshots of the free app, on iPhone. Same flow on Android.
The free app
reChain Grib turns the messages back into a weather chart.
Free on iOS and Android. It covers the whole workflow, from the request to the wind map, and works fully offline once installed.
- Request builderDraw your area on the map, choose model, resolution, forecast range and data. Your area and settings are remembered.
- Message estimateSee how many satellite messages a request will use before you send it.
- Reliable decoderPaste messages one by one or several at once. A progress bar shows which ones are missing, and received messages are kept until the file is complete.
- Offline wind mapCoastlines, countries and labels without network. Animated wind, color scale, isobars every 2 hPa, waves, and wind speed and direction with a tap.
- GRIB1 & GRIB2 exportOpen the file in qtVlm, OpenCPN, Expedition or any GRIB viewer.
- English & FrenchThe whole app is available in English and in French.
Reviews
Used offshore.
5 reviews posted on the App Store and Google Play, all 5 stars.
“Used for an Atlantic crossing, the app works very well and its developer is responsive when there's an issue.”
“Very good app! At last you can receive GRIB files on a Garmin inReach with no connection. An extraordinary alternative to the very expensive Iridium GO.”
“A complete app for receiving weather files off-grid through a Garmin inReach. And the developer responds quickly if there's a problem.”
“It really works, and it's surprisingly simple.”
See the app on the App Store and Google Play.
Pricing
Free to start. Unlimited for €9/month.
No waitlist and no credit card to try it.
Free
€0 / month
Enough to try reChain before your next passage.
- 3 requests per month (weather or assistant)
- No account, no credit card
- Works with your current inReach plan
⭐ Premium
€9 / month
Unlimited weather files and assistant answers, for every passage.
- Unlimited weather and assistant requests
- Cancel anytime
- One subscription per inReach address
- Fair-use policy to protect the service
Payments on this site are processed securely by Stripe. Premium is also available as an in-app subscription in reChain Grib (App Store and Google Play). Manage my subscription
Good to know: replies arrive as satellite messages on your own Garmin plan and count toward it like any other message. A weather file uses about 7 to 20 messages. If you use reChain often, a plan with unlimited messages is the most economical.
FAQ
inReach GRIB weather, answered.
Can a Garmin inReach receive GRIB files?
Not on its own: an inReach only exchanges short text messages of up to 160 characters. reChain works around that: the GRIB file is compressed and sent as ordinary satellite messages, and the free reChain Grib app rebuilds the original file on your phone.
How do I get a weather forecast on my inReach?
Install the free reChain Grib app, draw your area and copy the request it generates. Send it from your inReach to jcskipper.rechain@gmail.com. Within minutes the GRIB arrives as a few messages; paste them into the app to see the forecast.
How many satellite messages does a GRIB file use?
It depends on the size of the area, the resolution, the forecast range and the data you choose. A typical request uses about 7 to 20 messages. The app shows an estimate before you send, so you can adjust the request.
Which inReach models work with reChain?
Any Garmin inReach device that can send a message to an email address: inReach Mini 3 Plus, inReach Mini 2, inReach Messenger Plus, inReach Messenger, GPSMAP 66i and 67i, Montana 700i and 750i, and similar models. ZOLEO communicators are supported for weather too. You need an active satellite subscription.
What weather data can I get?
GRIB files from the GFS and ECMWF models via Saildocs: wind, sea-level pressure and waves, for the area, resolution and forecast range you choose, up to 7 days ahead.
How long does it take to receive the file?
Usually a few minutes after your request is sent. With a poor view of the sky, messages can take longer; the app keeps the messages already received until the file is complete.
Can I open the GRIB in my routing software?
Yes. Export the file from the app as GRIB1 or GRIB2 and open it in qtVlm, OpenCPN, Expedition, Adrena or any GRIB-compatible software.
What is Saildocs?
Saildocs is a free email service run by SailMail that sends weather files on request. reChain forwards your request to it, then makes the file small enough to travel through your inReach.
Set sail with reChain.
Three minutes is all it takes. Do it before you leave the dock.
- Install the free appreChain Grib, on iOS or Android, to prepare weather requests and read the files offline.
- Add the contactjcskipper.rechain
@gmail.com to your inReach contacts. No pairing, no account. - Create your tracking pageFree, so family and friends can follow your route and write to you. Create my page
Already convinced? Go unlimited: ⭐ Go Premium · €9/month