Boat polars describe your boat speed and wind angle in any given weather situation. Setting the polars up in your PredictWind account is important to getting an accurate weather route. It is essential you 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 have these set up they remain in your account for use in 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 degrees and 135 degrees.
% time downwind = True Wind Angle is 135 degrees or more.
In the PredictWind App go to tools then weather routing.
Tap on the settings wheel, then boat polars.
Under Boat type you can select from Predefined, Power & Sail and Advanced Polars. Advanced polars can only be set up in the PredictWind 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 making your selection.
On the forecast website https://forecast.predictwind.com/ go to Tools, then Weather Routing, then the Routing preferences tab.
In the Routing preferences there are 4 options for setting up your Polars, Predefined, Power, Sail and Advanced.
Predefined. We have a large selection of boat designs with their own full set of polars, you can select your type of boat or one that you know has a similar performance to your boat.
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 are great if you have a performance yacht and wish to define your polars for all points of sail, with different sail combinations. The format for Advanced polars can be seen here. You can add more columns and rows. It is essential to follow the format and have the two columns of 0 0 after the windspeed. (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 normal using the imported advanced polar.
If you are using the weather router for a Power vessel then use the Power option. We have 4 settings the first 3 are for in 15 knot wind conditions, upwind for when you are heading into the sea, 90 degrees for when you are heading with the sea on the beam and downwind for when you have the breeze from behind you. The next setting is your max cruising speed in perfect no wind conditions.
For all polar set ups, Professional package users can also set up a Wave polar to adjust your boats 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 will need to “Calculate" a route to save the polar in your account.
After calculating a route you will be able to 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 in relation to your actual boat speed. You can go back to preferences and adjust your polars if necessary.
Please click here for more information.