_____      _             _       _     
 |_   _|   _| |_ ___  _ __(_) __ _| |___ 
   | || | | | __/ _ \| '__| |/ _` | / __|
   | || |_| | || (_) | |  | | (_| | \__ \
   |_| \__,_|\__\___/|_|  |_|\__,_|_|___/

                                ___  ____  
          _ __ ___   __ _  ___ / _ \/ ___| 
         | '_ ` _ \ / _` |/ __| | | \___ \ 
         | | | | | | (_| | (__| |_| |___) |
         |_| |_| |_|\__,_|\___|\___/|____/ 

Step 1. Starting your free trial

The first step in getting started using the Offshore Data product is to start your free trial. This is done by selecting the menu item:

You will then see the following window:


When you press the large blue button on the left, you will be guided through a standard Apple in-app purchase process. During this process, the price (free) will be confirmed. Accept the “purchase” of the free trial to get started.

I suggest that before starting this free trial that you have access to the hardware you intend to use for your downloads, as well as access to your offshore email account.

Also, if you are new to the application, it may be worthwhile using it for a little while before starting this free trial.

Step 2. Choose the download method: email or ‘low speed internet’

This is done in the application Preferences, accessed via the menu item:


When you choose the email or low speed internet options you have the option to set the maximum file size. When the server is creating your Offshore file, if the resulting file becomes larger than this limit, then only the portion of the file that fits into the space allowed will be sent.

If you are using the email option, then both the approximate file and email size are provided. (When binary data is sent via email it must be encoded in ASCII, and this process causes the file to become larger.)

Step 3. Select the region


When downloading files via the Offshore Data service, you will want to carefully control the amount of data you are asking for. An important part of this will be specifying the region for the data you want to download. The normal method of downloading the region covered by the visible area of the screen is still available or course, but you will probably want finer control over this.

To specify the region, first select the Region tool, the rectangle tool in the toolbar which is highlit in the image above. Then, click and drag a region surrounding your area of interest. There will be opportunities to adjust this region later, if you wish.

If you are sailing, I suggest that you use the Routing feature in the macOS product. Before creating a region, create a fresh position report for your vessel so that you can have a visual indication of where it is. This will make it easier to adjust your region.

Step 4. Create your GRIB request


If this is the first request for this area, you will need to create a GRIB request for it. If you already have a request, you can simply adjust its region to correspond to your current needs.

You have a selection of a large number of GRIB models to choose from, including ocean wave and ocean current models.

Choose the parameters you want to download. You will probably want to limit the number of parameters to a select few, to keep your files small.

In the image shown above, you have the ability to change the resolution of the file download. On the open ocean, often even a 1° resolution is sufficient. Adjust the resolution, forecast hours, forecast duration and region until the estimated file size looks appropriate.

I prefer to give each request a filename, so that they are more easily identified in the file list (if you receive this data via email, this file name will appear in the subject line.)

Finally, click on the Download button to submit this request to the queue.

Step 5. …or edit an existing request

If you are on a moving vessel, you can often re-use the same request, as long as you modify its region to keep up with you. This can be done quite easily.


To modify the region for an existing request, open up the GRIB Request manager, and then open the information for the request you want. At this point, you can edit the region with several options, as shown.

When you are finished modifying this request, click on the Download button to submit it to the queue.

Step 6. Email or Low speed internet?

At this point, the interaction is slightly different, depending on how you are going to obtain your file:

Copyright © 2019 Craig McPheeters. All rights reserved.