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 and Speed 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 on your device.
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 start generating AI polars, you will 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.
Choose either 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, otherwise the AI will see the data being captured as an outlier at 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 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 copy your Predefined polars across to Advanced. Now selecting Advanced you are able to edit the boats dimensions.
Using Advanced Polars
Set the Boat Dimensions. From the dropdown box, select either Sail Monohull, Sail Catamaran, etc 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
It will take a few minutes for the server 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 later decide that you have set the wrong Base Polar, you can change 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. Please note it is important that the Base Polar is a close match to your boats 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'll be able to 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 sailboats 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 leaving this automatic polar generation feature on 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 14km 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 using a GO exec: The DataHub will average 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, and so if you are only sending GPS tracking positions and polar data, there is no extra cost to uploading the polar data.