Boat polars describe your boat speed and true wind angle in any given weather situation. Setting the polars up in your PredictWind account is important for an accurate weather route. You must set the polars up in your account before using the weather routing and departure planning tool on any of the PredictWind platforms.
Setting up your Polars in your PredictWind account must be completed on the PredictWind forecast website or within the PredictWind App. Once you set these up, they remain in your account for use on all platforms, including the Offshore App.
See below the wind angles we use to define upwind/reaching/downwind.
% time upwind = True Wind Angle is 55 degrees or less.
% time reaching = True Wind Angle is between 55 and 135 degrees.
% time downwind = True Wind Angle is 135 degrees or more.
PredictWind App
Under Weather Routing, click on Sail Routing or Power Routing.
Tap on the Settings cog, then Boat Polars.
Under Boat type, select from Predefined, Power / Sail, Advanced or AI Polars. Advanced and AI Polars require initial setup on the PredictWind Forecast website.
Make your selection.
Tap back to go to the weather routing map.
Tap on Calculate to validate your polars in your account; you must run a weather route after selecting.
Forecast Website
On the forecast website https://forecast.predictwind.com/ go to Weather Routing, select Sail Routing or Power Routing, then the Routing preferences tab.
In the Routing preferences, there are four options for setting up your Polars: Predefined, Power/Sail, Advanced and AI Polars.
Predefined
We have a large selection of boat designs with their own complete set of polars; you can select your type of boat or one that you know has a similar performance to your boat.
Sail polars
Sail Polars are very simple to set up and are suitable for cruising boats, where you cannot select a predefined polar. Enter your boat speed at 50. 90. And 160 degrees true in average 15-knot wind speed conditions. We assume this is the max speed for the vessel, and the boat speed decreases as the wind drops.
Advanced Polars
Advanced polars are great if you have a performance yacht and wish to define your polars for all points of sailing with different sail combinations. The format for Advanced polars can be seen here. You can add more columns and rows. (Do not copy in the TWS, TWA and Boat Speed labels). The first TWA column is your upwind target; the last TWA column will be your deepest downwind angle.
We now have a Polar Import Feature. On the Advanced Polar section of the Weather Routing Preferences, you can import a '.txt' file (PredictWind format) and a '.pol' format polar. The imported polar will automatically fill the Advanced Polar Text Box. '.pol' polar files will be converted to the PredictWind format before being pasted into the Text Box. You can then calculate a route as usual using the imported advanced polar.
AI Polars
To use AI Polars, you must have a DataHub and PredictWind Professional Forecast subscription. Select AI Polar on the Routing Preferences page, then select Use my latest AI Polar to run future routes from DataHub collected Polar Data. To get started, click Edit Base Polar, then set your boat's predefined settings as a base data set to be improved upon and click Save Base Polar.
For more information about AI Polars, please see this article.
Power Polars
If you are using the weather router for a Power vessel, then use the Power option.
The optimal route will deviate based on the weather and waves to minimise the total fuel used over the whole route. In the Summary Tables on the Wind and Summary tabs, you'll find a row detailing the fuel used for each route.
Other Notes
For all polar setups, Professional package users can also set up a Wave polar to adjust their boat's performance in different wave conditions. It is simply a % of your base polar and will be calculated using the wave conditions from the forecast.
All other routing preferences, which include Motoring settings, Comfort settings and tidal and Ocean currents, can be adjusted in each platform, but they do not transfer across platforms.
Once you have set up your Polar preferences, you must Calculate a route to save the polar in your account.
After calculating a route, you can see the weather routing results. Please take some time to analyse the results in the tables. The wind tab will give all the points on the route, comparing the wind speed to boat speed at various angles and speeds. It is important to check your routing results to your actual boat speed. You can go back to your preferences and adjust your polars if necessary.
Please click here to contact us if you need more help or information.