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2023 Atlantic Crossing Weather Tools Webinar (Part 2)
2023 Atlantic Crossing Weather Tools Webinar (Part 2)

The 2023 Atlantic Crossing Weather Tools Webinar (Part 2/2) was recorded on 19th October 2023

Keryn McMaster avatar
Written by Keryn McMaster
Updated over a week ago

The Atlantic Crossing Weather Tools Webinar (Part 2) was recorded on 19th October 2023

Here is the link to the video on YouTube:

This advanced webinar details how to use the equipment and PredictWind Weather Tools for an Atlantic crossing. Topics include:

  • Using the Offshore App while on Passage

  • Connecting to your Satellite device

  • Offshore App Settings for Satellite Downloads

  • Tools in the Offshore App

  • How to use new features, Wave Routing, GMDSS maps, and AIS during Offshore

Below, we answer the 11 most commonly asked questions:

1. Why should I get a professional subscription to PredictWind?

The professional package gives you access to the best data that PredictWind has to offer. The Professional level allows access to the following:

  • High-resolution forecast GRIB files (1km and 8km PWG/PWE, 9km ECMWF, 27km GFS, 14km SPIRE & 10km UKMO)

  • Ocean current GRIBs (Mercator, Hycom and RTOFS)

  • Sea Surface Temperature (SST).

  • High-resolution tidal currents

  • Wave modelling of your boat (including Roll, Vertical accelerations and Slamming Incidence). Please learn more with this 1min video.

  • AIS data in the Offshore App, accessible via satellite when offshore. Please learn more with this 1min video.

Any weather route or departure plan calculation using either the Standard or Professional subscriptions will consider your choice of ocean current data and wave polars when calculating a route. However, only the Professional subscription will show you these details when viewing the results in the tables and along the routes.

2. What are boat polars, and how do I set them up?

Polars describe your boat speed and wind angle in any given weather situation. Setting the polars in your PredictWind account is essential for an accurate weather route. It is vital you set the polars in your account before using the weather routing and departure planning tool on any of the PredictWind platforms.

See the help at for detailed instructions on setting up boat polars.

3. What is the difference between the PredictWind App/ website and the Offshore App?

There are multiple ways you can view a PredictWind forecast:

  • The PredictWind website is used on your PC/ Mac using a web browser like Chrome or Safari. You need complete internet services to use this. It is location-based, i.e. you add your location, and we generate a forecast for that spot. This is our primary platform for subscription management, billing, and setting boat polars.

  • The PredictWind App is installed on your mobile device and is an online tool. It needs Wi-Fi or a cellular connection to view the forecast. It is location-based, i.e. you add your location, and we generate a forecast for that spot.

  • You can use the PredictWind Offshore App on PC, Mac, Apple or Android devices. It is an offline tool for downloading compressed GRIB file weather data and weather routing via an internet or cellular connection, at sea via satellite like the Iridium GO or email request. It stores files locally on the device to review offline.

4. Can I find out more about GPS Tracking?

PredictWind can provide a customized GPS tracking web page for your boat. Your friends and family can access this web page and do not require them to have a PredictWind account. The web page can be viewed in a web browser or embedded in your blog or website.

You can utilize our GPS tracking and blog post features with an Iridium GO, YB3i, YB Tracker, inReach, or manually update your position report via the Offshore App.

Check out our Help Centre Section on GPS tracking at for more information.

5. What is a Datahub, and why do I need one?

The DataHub is your all-in-one GPS tracking, data management, and communication solution. Whether you're offshore or inshore, it seamlessly handles your GPS tracking, data sharing, and communications. It can switch from satellite to cellular when needed, ensuring your tracking page stays current. Plus, it offers features like firewall protection, PredictMail, generating AI boat polars, accessing N2K data, and broadcasting GPS and AIS. There are no ongoing fees or contracts with the DataHub, just the requirement of a standard or professional PredictWind forecast subscription for GPS tracking services.

6. Can I get more information on the new AIS and GMDSS/ Extreme Weather Warnings features?

7. What satellite devices are compatible with the Offshore App so I can download PredictWind weather files while at sea?

There are multiple ways to download PredictWind weather data while offshore. Our Offshore App is compatible with the Iridium GO!, Iridium GO! exec (recommended), Iridium phone with Optimizer*, GlobalStar, high-speed satellite devices including Starlink, email requests, and SSB with a pactor model, Iridium handset, Aurora, Glow, MCG101, SatStation, Sattrans, Thuraya, Isatphone, Iridium Pilot.

*If you have an Optimizer connected to the following devices, you can directly download GRIB files and routing.

8. What is the recommended file size for weather downloads?

Iridium GO: We recommend keeping the file size below 200kb. The rule of thumb is that 100kb takes 10 minutes via the Iridium GO, with a data speed is 10-12KB/ minute.

Iridium GO! Exec: We suggest keeping the download file size to 500KB, but you can get larger files and ocean data, wave data and AIS offshore with the Professional level PredictWind forecast subscription.

9. What is CAPE, and how can I predict severe weather?

CAPE stands for Convective Available Potential Energy and is the amount of fuel available to a developing thunderstorm. More specifically, it describes the atmosphere's instability and approximates updraft strength within a thunderstorm. So, CAPE is used by weather officials to understand what the potential might be for thunderstorms and how powerful those storms might become if they do materialize.

The standard measurement of energy is represented as Joules Per Kilogram. Weather experts might also express A high CAPE value using the term “high instability”. When we talk about a highly unstable atmosphere, CAPE values are usually more than 2500 J/kg, which would supply ample energy for strong updrafts and violent thunderstorms, should they develop.

You can learn more about CAPE and other indicators for predicting severe weather at

10. How do I set up wave polars?

With PredictWind Weather Routing, you can set your Wave Polar not only to define the performance of your boat in various wave conditions but also to view the Roll, Vertical accelerations and Slamming Incidence that your boat will experience through the route. See more information at

11. Can I get the link to the Part 1 webinar?

The first webinar in this series can be viewed here. It covered our recommended weather and communications set-up, including the Iridium GO!, Iridium Go! Exec, Starlink, a brief overview of the PredictWind Offshore App and GPS tracking.

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