DataHub Automatic Polar Generation
To take advantage of this great feature, you will need the following:
A PredictWind Professional Forecast Subscription.
A DataHub connected to your NMEA 2000 instrumentation system outputting Apparent Wind Speed, Apparent Wind Angle, Speed over Ground and Course over Ground.
GPS Tracking must be enabled on your DataHub. AI Polar data is uploaded with GPS tracking position reports being sent.
There are two important steps:
1) Enable AI Polars in the DataHub
Connect your laptop (recommended) or mobile device to the DataHub Wi-Fi. It will look like PW-Hub-XXXX in the list of available Wi-Fi networks.
Open a Chrome or Safari browser and type 10.10.10.1 in the URL bar.
Log in with username admin and password admin.
From the left menu, select AI Polars, then click on the check box Automatic Mode, then click Save & Apply.
2) Set your Base polar on the PredictWind Website.
To generate AI polars you need to set a base polar on the PredictWind Website.
On a PC or Mac, log in to https://forecast.predictwind.com, then go to the Weather Routing > Sail Routing.
From the Routing Preferences tab, select AI Polar as your boat type.
Click Edit Base Polar and choose Predefined or Advanced from the dropdown list.
Only use Advanced if you have set up Advanced polars and have used them extensively in the past.
It is important to have the Base Polar set correctly to the known performance of your sail boat, otherwise the AI will see the data being captured as an outlier and it will take a lot longer to generate accurate polars.
Using Predefined Polars
Set the Predefined Polar using the dropdown box that appears to the right.
Once you've found your sail boat, everything is set, including the boat dimensions.Click Save Base Polar to start generating polars.
If you wish to change the boat dimensions, perhaps the displacement is a little light, then you will need to select your Predefined Polar and click Copy To Advanced Polar.
Now by selecting Boat Type: AI Polars > Edit Base Polar > Set AI Polar: Advanced, you can edit the boat dimensions.
Click Save Base Polar to set.
Using Advanced Polars
Set the Boat Dimensions by selecting Sail Monohull, Sail Catamaran, etc., from the dropdown box, depending on your boat type.
Next, fill out the Displacement, Water-Line-Length (LWL), Beam and Canoe Body Draught (Draught).
With everything set correctly, click Save Base Polar.
Notes
AI polars will work within 24 hours of your PredictWind Forecast account being subscribed to Professional and your DataHub uploading AI Polar data.
Once set up on the Forecast website, the server will take a few minutes to generate the first version of your AI polar. After a few minutes, refresh the page, then calculate your first route using the AI polar. Each time our servers receive new data from your DataHub, a new AI polar will be generated, further refining the accuracy.
If you run a route and the error Please see red field appears, please refresh the page.
If you realize you have set the wrong Base Polar, you can change it and save it to something else. The server will start from scratch using all data we've received in the last 3 months to accurately generate a new AI Polar based on the modified Base Polar.
It is important that the Base Polar is a close match to your boat's performance.
How do I know the AI Polars are being updated?
You will see a dialogue like the one below. While Use my latest AI polar is checked, the router will use your most recently generated DataHub polar. By deselecting the checkbox, you can see a list of all generated polars, date stamped from the dropdown.
How do PredictWind AI Polars actually work
The polar data uploaded to the PredictWind servers update your Base Polar in real-time. Using a filtering technique, the AI algorithm decides if the data represents the sailboat's performance in the given conditions and is useful in updating the polar.
For example, if polar data points are sent whilst you are at anchor, they will be discarded. Likewise, it will also be ignored if you are sailing but have the boat set up so that you are sailing much slower than normal. There is also a night adjustment to the auto-polar, so it is not required to set a Night Time Polar Speed Adjustment. As a rule, the more data collected, the better the accuracy of the AI polar, so we recommend enabling Automatic Mode on the DataHub permanently.
The polar generation process uses GPS speed over ground and course over ground, as it requires no instrument calibration of a boat speed sensor. It uses tidal current modelling from PredictWind's worldwide coastal model to make corrections for the effects of current. In addition, the polar generation considers the effect of waves by using the ECMWF 8km wave model. If you have speed through the water data available to the DataHub, it will use that in preference to the tidal current modelling.
The format of this AI Polar is quite different, considering Wind Speed, True Wind Angle and Significant Wave Height / Angle / Period from the ECMWF model. The inclusion of wave data is a technological breakthrough in polar generation to give a more real-life representation of the boat's performance in all conditions. This AI polar can be used in the PredictWind weather routing for greater accuracy and, hence, safety for the crew.
Important Note for GO exec MB plans subscribers: The DataHub averages the NMEA data required for polar generation every 1 minute. These 1-minute averages are uploaded to the PredictWind server when a GPS tracking position is sent.
Iridium has a minimum billing increment of 5KB, so if you only send GPS tracking positions and polar data there is no extra cost to upload polar data.
Troubleshooting AI Polars
A DataHub is required for AI Polars
If you have a DataHub and see the error message "A DataHub is Required for AI Polars" on the forecast website, please email support@predictwind.com with your DataHub serial number and your boat name so we can link your PredictWind account to your DataHub.
