Saildocs Information and News

About this page

This page contains copies of an information documents supplied by sending a blank emails to Saildocs addresses;

First is a general info document

Appendix 2 is a copy of, the Saildocs email describing the acquisition of GRIB files

At Appendix 3 is a copy of the latest an occasional Saildocs GRIB Newsletter

Saildocs provide a number of other useful services aimed at those using Marine HF or HAM radio. These are listed at Appendix 1 to this page. \\

General Saildocs Info File Apr 11, 2002)

Thank you for your interest in Saildocs, an Internet service for the bandwidth impaired. Saildocs offers text-based document retrieval and subscription services for offshore sailors, adventurers, missionaries and others who somehow live their lives without DSL lines. There are currently two services offered, a document retrieval service which will return documents from the Internet or our own files, and a subscription service which will send Internet documents (for example weather reports) at scheduled intervals. Saildocs is supported in part by Sailmail ( but is an independent service which can be used by anyone who agrees to the terms and conditions (below).


Saildocs can either retrieve documents from its own library, internet documents which are in its home (primarily text weather information), web pages, or grib data (specialized weather data files).

Documents are requested by sending an email to: The subject line can be anything, and the body of the message contains requests of the form "send xxx" where "xxx" is the name of the document. The word "home" has a special meaning and sends the current library home, and a document called "info" (this document) is always available. For example, to request the home and help documents, send the following message:

Subject: (anything)

send info
send home

You can follow this with the command command "quit" or just end the message.

Requesting weather bulletins:

Once the home is received, request one or more weather catalogs (for example "send peace" for the available Eastern Pacific bulletins). Then request the bulletin by using the code from the catalog:

send FZPN02.KWBC

Requesting web pages:

Saildocs can also fetch documents from the web and convert them to plain text. Send a message to, with "Send" followed by the URL (web address) as follows:

Subject: (anything)


This will fetch the Sailmail home page.

For information on requesting grib files, send an email to


Saildocs will send requested documents on a periodic basis. To enter a subscription you need the same code that is used for a request, above. Any request can be turned into a subscription by changing the "send" command to "sub" (or "subscribe"). Once you determine which forecast(s) you want to subscribe to, send a subscription :

Subject: (anything)


This enters a subscription for the Boston and Chesapeake Coastal forecasts (see the "nws-atl" home). By default these are fetched once per day. The period and time can be overridden by adding commands as follows:

FZNT23.KWNM time=00:00 interval=6

This will fetch the document every 6 hours beginning at 00:00z. Subscriptions are normally entered for 14 days, a different period can be specified as follows:

FZNT23.KWNM days=7

A confirmation will be sent for any changes to a subscription. In addition, a full status listing can be requested by including the command "status", e.g.

FZNT23.KWNM days=10 time=12:00


To cancel a subscription, again send a message to with the "cancel" (or "unsub" or "unsubscribe") command and the document codes as above. For example:

Subject: (anything)

cancel FZNT23.KWNM

Some things to remember:

By requesting a document or subscription from Saildocs, you are acknowledging that you have read and agree to the following terms and conditions: The Saildocs is an automated service which is offered without charge on an as-is basis, without any warranty or assurances that it will work, be useful, or that the information delivered will be correct. Saildocs is an automated computer system which is subject to a variety of hardware problems and software errors, and also depends on internet communications with other computers which themselves may or may not work. Saildocs has no control over the content of the information from other sources, and in particular, weather forecasts may be missing, incorrect or out of date.

Known limitations:

Re-directed sites (i.e. web pages which are simply pointers to another address) do not work.

Long URL's require properly formatted Mime-encoded messages and may not work with all email systems;

Web pages translate to text with varying degrees of success. The fancier the page, the worse the results. There are also other web-to-text services that may produce a more useful output for some pages.

For more information or to report a problem, please send email to
Enjoy the system, and be careful not to overload your email channel!

Thanks for using Saildocs, an Internet document retrieval service for the bandwidth impaired.

Saildocs is provided without charge thanks to the support of Sailmail, a membership-owned radio email service for cruising sailors which
operates a seamless network of 13 stations world-wide (including five covering the Caribbean and Atlantic). For more information on
SailMail see the web page at or send a query to the office at

More information on Saildocs is available by sending an email to, this will return the how-to document (about 5K).

Appendix 1

The following information files are available by sending an email to "", (subject anything) and enter the command "Send XXXX" (without quotes) as the message,

where "XXXX" is the document code from the list below. Multiple "send" commands can be included in the same request (each with the word "send" and each on a new line). The list is US dominated and aimed at long distance cruising yachts but some items will be of general interest.

Document code nam







Requesting grib files from Saildocs




Grib news (28 Dec 2002)




Grib news Vol-2 (28 Mar 2003)




Grib news vol. 3 (June 30 2003)




Grib news vol. 4 (June 15 2004)




Saildocs Info File




Talk-power mod for Icom m802




Index- GMDSS MetArea forecasts




Fiji Meteorological Service




Index- Polar Orbiter Satellite Predc

nwpac                 ;



North West Pacific weather bulletins




NWS FORECASTS - ALASKA (revised 3 Ju...




NWS Atlantic weather codes


















Scuttlebutt 1626




Index- South Pacific weather bulletins

Appendix 2

Copy of

Subject: Requesting grib files from Saildocs (2006-07-25)

Custom grib data-files are available from Saildocs. These are extracted on a per-request basis from global computer models and can cover any requested area. The resulting file can be anywhere from 1K bytes to megabytes depending on the amount of data requested. Reasonable-sized files can be sent via low-speed data links such as radio email.

Important note: Grib files are computer-generated forecast files from a NCEP/NOAA computer, which are sent without review, and are offered on an as-is basis. There is no assurance that the data is available, accurate or correct. Both Saildocs and the computer model itself are automated systems, subject to a variety of failures and errors. By using the data, you acknowledge and agree to these limitations.

Viewing grib files:

A simple grib-viewer is available as part of Viewfax, Airmail's fax and image viewer. More info is available from the "gribnews" document (send a blank email to You can also view gribs with many charting programs, see below.

Requesting a grib file:
Saildocs is an automated system and the format for a grib request must be followed exactly.

The format for a basic grib-file request is:

"lat0,lat1,lon0,lon1" are the lat-lon limits (whole degrees followed by N/S or E/W)- this field is required, there is no default.
"dlat,dlon" is the grid-spacing in degrees (e.g. "1,1" for a 1-deg by 1-deg grid), if omitted the default is "2,2". The minimum grid depends on the model, see "available models" below. This parameter has a large effect on file-size, see below.
"VTs" is a comma-separated list of valid-times (forecast-times, e.g. "24,48,72"), if omitted the default is "24,48,72". Available valid-times depend on the model, see below. Note that forecasts beyond 4 or 5 days should be viewed with increasing skepticism.
"Params" is a comma-separated list of parameters, default is pressure and wind if omitted.

The "|" separator-character is the same vertical-bar character used with grib-requests, and is upper-case "\" (above the "Enter" key) on US-format keboards, or AltGr and "-" on most international keyboards. Alternately the "/" or "¦" characters can be used.

If the entire request does not fit on a single line then insert a "=" character and continue on the next line-see example below. Do not include any extra spaces before the "=".

To request a grib file which covers 20N-60N and 120W to 160W, on a 2-degree grid for valid times of 24 to 72 hours, containing surface pressure and wind, send the following email:
Subject: anything

send gfs:40N,60N,140W,120W

Note that this is identical to:
send gfs:40N,60N,140W,120W|2,2|24,48,72|PRESS,WIND

IMPORTANT: Do not insert any extra spaces, Saildocs uses spaces to delimit parameters.

This example is around 2K bytes. The size is proportional to the number of data-points: i.e. the size and resolution of the grid, the number of valid times, and the number or parameters, figure 1.5 bytes per point. The biggest effect on file-size is the grid spacing, a 1,1-deg file is 4x larger than a 2,2-deg file.

These are uncompressed binary files which get compressed when sent via Sailmail or Winlink radio links, so there is no advantage to pre-compressed files.

The request must fit on a single line. However a long request-line can be broken with a "=" character as follows:
send gfs:20N,60N,160W,120W|2,2|6,12,18,=
24,36,48,72,96|PRESS,WIND time=12:00

A shortcut is also available for a long list of forecast-times, for example:
send gfs:20N,60N,160W,120W|2,2|6,12..96|PRESS,WIND
This means 6, 12 hours and then repeat the same 6-hour interval out to 96 hours.


To subscribe to this sample grib, use the same format and change the "send" to "sub" (or "subscribe"), for example:

Subject: anything

sub gfs:40N,60N,140W,120W

This will enter a subscription which will be sent shortly after 06z (utc).
The default subscription is 14 days, to change this add a space and "days=30" for a 30-day subscription, (or "days=0" for an indefinite subscription). Other times can also be requested. For example:

sub gfs:20N,60N,160W,120W days=30 time=18:00

Available models
The primary source for grib files is NOAA/NCEP's "GFS" global model (request-code "gfs:" or "grib:"). Available forecast-times are 0,3..180 hours on a 0.5-deg grid and 192,204..384 hours on a 2.5-deg grid. (Note that 0.5-deg data is not always available, in that case Saildocs will default to 1-deg). Available parameters are PRMSL for mean sea-level pressure, WIND for the gradient surface ((10-meter) wind, HGT for 500mb height, SEATMP for sea-surface temp, AIRTMP for air temperature (2M altitude), and WAVES for wave-height (from the WW3 model). The model data is updated shortly before 06:00z for the 00z model-run and every 6 hours.

Data from other NOAA and US Navy models is available, send a (blank) email to: for details.

Canceling a subscription

To cancel a subscription, send the same message except change "sub" to "cancel". The grib-code must match exactly, even if it is incorrect. Cancelation instructions are also included with each subscription message.


Grib files generated by Saildocs are standard WMO-format grib file which can be viewed with Airmail's Viewfax viewer or most charting programs including Coastal Explorer, Deckman for Windows, Expedition, Maxsea, or Raytech, or any other program that uses standard grib files. (Oddly, Nobeltec does NOT support standard grib formats).

Gribs are sent as Mime-coded file attachments and can be sent via radio email via Sailmail ( or the Winlink ham-radio system ( When using any low-speed connection attention must be paid to the file-size. Sailmail will handle grib-files up to 30K (10K for Pactor-2) but that may be too large depending on distance, conditions and connection speed. Winklink allows attachments after the use has set an attachment limit, this is done by sending a Winlink-2000 Options message (Airmail's Windows menu).

Support addresses:
To get general info about Saildocs send a (blank) email to: (auto-responder)
For problems/questions relating to Saildocs, send an email to
For problems using any of the charting programs see the respective manufacturer website.

Saildocs was started in 1999 to provide internet weather data to Sailmail members. It was created and is supported by Jim Corenman, who co-founded Sailmail with Stan Honey and wrote the Airmail software. The grib project started in 2002 as a "science project" and has recently moved to a new server with high-bandwidth connections to NOAA's servers. Saildocs continues to be available without charge thanks to the support from Sailmail (

Thanks for using Saildocs and Good Sailing!

Thanks for using Saildocs, an Internet document retrieval
service for the bandwidth-imaired.

Saildocs is provided without charge thanks to the support of Sailmail,
a membership-owned radio email service for cruising sailors which
operates a seamless network of 13 stations world-wide (including
five covering the Caribean and Atlantic). For more information on
SailMail see the web page at or send a query to
the office at

More information on Saildocs is available by sending an email to, this will return the how-to document (about 5K).


Appendix 3

Copy of Grib News letter June 15 2004 -

This is an irregular newsletter about grib weather data from Saildocs. If you wish, you can enter a subscription and a copy will be sent whenever there is an update, see below for info. Previous copies are available via Saildocs by requesting "gribnews-1" for vol-1 (Dec-2002), "gribnews-2" for vol-2 (Mar 2003), gribnews-3 (June 2003). The most-recent version will always be available as "gribnews".

The GFS model data continues to be downloaded every 6 hours. Other than very occasional problems with the NOAA/NCEP server it continues to run smoothly. As discussed in Gribnews vol-2, the requested times are referenced back to 00:00 UTC, this "valid-time fudging" ensures consistency irrespective of when the grib is requested but can add confusion. See the last newsletter for complete details ("gribnews-2"). If you want to avoid the time-fudging see below for the "gfs:" prefix.

Recent developments include some additional error-checking on grib suscriptions, and availablility of "Coamps" high-resolution data for the Carib and the west-Atlantic (see below).

The primary grib data from Saildocs continues to be from the GFS model. Data is currently available at 6-hour increments out to 96 hours, and at 12-hour increments out to 180 hours. Additionally, for the 00z and 12z model-run (available at 06:00 and 18:00z) data is available out to 360 hours (15 days) on a 2.5x2.5 grid. (Remember that forecasting beyond 4 or 5 days becomes increasingly speculative). The primmary supported dataset continues to be the original 12-hour increment out to 96 and 24 out to 240. What that means is that those times have priority and get downloaded first, and then (assuming that things are working OK) the "odd" times (6,18,30 etc) are downloaded.

Valid-times: The "fudging" of valid-times to reference everything to 00:00z is intended to provide consistency for folks who do not necessarily request a grib file at the same time each day. But for those who want the most-recent data and don't care about consistency from their previous request, an alternative "gfs:" prefix can be used instead of "grib:". The syntax is identical, the only differences are that the valid-times will not be altered from the request, and data is available out to 360 hours for each model-run.

Regional models: Current global models do a very good job over open water, but suffer near land. An alternative is to take the data from the global model, and use it as input to a regional (mesoscale) model on a finer mesh with more detailed modeling of land effects. One such effort is the US NAvy's COAMPS ("Coupled Ocean/Atmospheric Mesoscale Prediction System") model, which is available for the eastern Pacific, Central Americal and western Atlantic with a resolution of 0.2 x 0.2 degree. This data is now available on the internet, and is available from Saildocs on an experimental basis. This data comes from a server which is not an official "production" server, and is on an "as-available" basis.

The Eastern Pacific region has been available for the last year, and three additional regions are now available: West-Atlantic, Carib/Central-America, and Contintal-US (including the water along the edges which are the interesting bits). The syntax is the same as for a basic grib, except the prefix "coamps:" is used in place of "grib:", and the grid can be specified as small as "0.2,0.2". For best results, stick with 0.2 or multiples of that, to avoid interpolation.

The areas for the available coamps areas are:
East-Pacific: 29n,60n,160w,114w
West-Altantic: 20n,55n,093w,055w
Cent-Am and Carib: 00n,32n,120w,060w
Continental US: 24n,50n,126w,066w

(The same "coamps" prefix is used for all regions, Saildocs sorts out which file to use).

The availability of regional models is an exciting area particularly for coastal sailors, as it has the promise of providing better predictions of near-coastal weather. (The definition of "near-coastal" varies, but generally the effects of a large landmass will be felt out to around 200 miles). Many weather services run global or regional models but unfortunately most governments have not followed the US lead in making data produced with public funds available to the public. We are fortunate and grateful, and hope that citizens of other countries will take the message home that making this information available benefits everyone.

Note that Airmail's grib-request window does include these the "gfs" and "coamps" codes, create the request and then modify it before sending.

To subscribe to this: send an email to: with the following message:
sub gribnews days=0
That will enter an indefinite subscription to the "gribnews" newsletter. General information about grib files is available by requesting "gribinfo" (or mail to:, and general info about Saildocs from


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