Thursday, December 20, 2012


Application: iPhone, iPad, iPod Touch 3rd gen, requires iOS 5.0
Function: Calculate polar diagrams for sailing performance
Rating: ***
Cost: $9.99

Your average boater is not going to have a clue what a polar is. Let me first say it is not where Santa Claus lives and it has nothing to do with an Express train either. Sorry for the Christmas references but it is the season. Sorry, it was a very lame attempt at a joke to get you to read the rest of the post. Now that I have your attention, the cute bear picture is compliments of!

If you are a sailboat enthusiast you may be interested in the app called iPolar.  The very smart people at KND-Sailing Performance from Valencia Spain have built this Velocity Prediction Program (VPP) app to help you quickly create polar diagrams and data with a few inputs of the boats vital statistics.  Polar diagrams are a very complicated subject and I will not go into a complete explanation here. You can Wiki or Google it to find out more. Basically, a polar diagram is the graphical diagram, consisting of the theoretical maximum boat speeds at various true wind speeds and headings, along with the associated upwind and downwind VMGs (velocities made good).  Knowing your boats optimum points of sail with respect to the wind can give you an edge in a race or get your across oceans is a shorter amount of time.

  • Calculate polars for cruising yachts 8-20 meters
  • No multi hull support
  • Length Overall input
  • Displacement input
  • Mainsail area input
  • Jib area input
  • Unit in metric or imperial
  • Length Waterline input
  • Symmetrical Spinnaker area
  • Asymmetrical spinnaker area
  • Resulting polars can be visualized as a graph or table of numbers
  • Polars can be sent directly to the weather/routing application such as Weather4D Pro
The app will calculate a polar for each sail configuration in the input data.  iPolar will compute a polar diagram describing the yacht's performance in kts for wind strength ranging from 4 to 30kts and true wind angles ranging from 0° to 180°.

The app has three soft keys at the bottom of the screen. These include Parameters, Polars and Values.

The Parameters page is where you enter your boats name and mandatory data of Length, Displacement, Main Sail area and Jib sail area. Several different boats and configurations can be added to the app.

Optional parameters include Length at waterline, symmetrical spinnaker area and asymmetrical spinnaker are.

The Polars page shows you the diagram of your yachts. Note the two buttons at the top for selecting the Main-Jib configurations and the Main-Spinnaker option.

The app is designed to develop polars for cruising and racer/cruising types of sailboats.

The accuracy of the polar data decreases for yachts that have measurements or displacement to length ratios outside the range of production cruising yachts.

The Wind speed can be adjusted with the slide bar at the bottom of the screen. Note the different diagrams drawn on the chart.

The tabular Polar data is displayed under the third tab called Values. Wind speed is across the x axis and direction is on the y axis.

The polar data can also be exported to the Weather 4D Pro app. Select the arrow icon at the top to export the data.  The Weather 4D Pro app has a weather routing module that will calculate the optimum route for the current wind and boat polar parameters.

The custom polar diagram can be selected within the Routing module of the Weather 4D Pro app.

This is all pretty technical stuff and your average boater may never need to consider this level of detail.  If your a true ocean racer and want to get the best performance out of your yacht, iPolar will give you some data to improve your performance and cross oceans in the most efficient manner.  The Weather 4D PRO app is another great app to use when planning passages.

Christmas is coming soon and I hope all of you have your shopping done. If you know some Geeky sailor who might want to calculate Polars, I have just the stocking stuffer for him, iPolar.

~~~Sail On~~~ /)  

 ****Happy Holidays****

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