iPolar generates speed polars for Weather4D PRO

iPolarYou dreamed of it since Weather4D Pro has featured its powerful routing module. He did !

Our Toulousian crazy developer, Olivier Bouyssou, just sent Apple a new app : iPolar.

Developed in collaboration with - and on behalf of - KND SailingPerformance, iPolar calculates polar performance of a yacht according to specific parameters, easy to identify :

  • LOA (Length Over All)
  • LWL (if unknown, iPolar use a default 95% LOA)
  • Displacement
  • Mainsail surface
  • Jib surface
  • Spinnaker surface (optional)
  • Asymmetrical spinnaker surface (optional)

Polars are calculated automatically when input is performed. They can then be displayed in iPolar graph and table format :



The polar can then be exported directly Weather4D PRO to feed the routing module (¹).

iPolar dans Weather4D PRO

Explanations :

iPolar is a VPP (²) that predicts speed polars from a small number of parameters : length, displacement and sail area. This simplicity creates a number of restrictions : iPolar is designed only to correctly predict cruising and racing monohull polars. At time, only monohulls with LOA between 8 meters. and 20 meters. are treated.

For sailboats whose parameters are outside the expected range for iPolar, the use of more advanced VPP is required. KND-SailingPerformance uses NorthSails VPP, developed through several cycles of America's Cup. In this case the VPP calculates polar matrices from full hydrodynamic coefficients (from CFD calculations) and aerodynamic coefficients. In case you are interested in such a VPP, contact directly SailingPerformance.

KND SailingPerformance :

This small company located in Valencia, Spain was founded by three senior engineers in the fields of mathematical modeling, naval architecture and performance analysis. They got a reputation for expertise applied to racing for over ten years, actively assisting famous boats in America's Cup, The Volvo Ocean Race, Vendée Globe, and many others.

For data boats, you can refer to specialized websites, France as excellent Select a boat the François Kammerer, a fellow of Loire-Atlantique.

iPolar should be available within a few days on the Apple AppStore for 9,99 €. We will not fail to talk about it again during the Nautic, on the stand of iTabNav.fr (Hall 2.1 – Stand D41).

(¹) See my post Routing comes up in Weather4D PRO 1.3
(²) Velocity Predicting Program


6 Replies to “iPolar génère des polaires pour Weather4D PRO

  1. I just made a comparative calculation of polar Ipoar my boat with what I had already noted in the estimated 3 derrnières years of sailing.
    The calculation seems to me very close. So I'd rather have a favorable opinion on this application. Anyway for people like me who use the routing security and not the race that's enough.
    Congratulations to Francis and Olivier continue to concoct powerful tools at low cost.
    Their work is greatly appreciated.

  2. Hello,
    Knowing my boat polars am interested. They allow me to use routing pro W4D.
    I have a particular boat. It is gunter rigged cutter. I have a gunter mainsail, forward a staysail and jib. I also have a gennaker.
    Is this rig can fit ipolar.
    Thanking you.

  3. Hello,
    Thank you for this information.
    It is not considered an app that builds polar speed in real time ? It would then boat specific data, sails state, the talent of the helmsman ! 🙂
    To build a polar, if I'm not mistaken, must : boat speed, wind speed and direction. All these information can be available as NMEA data, isn't it ?
    Further remark : often standard boats polars are given by the builder or architect.

    1. Hello,

      Good point. The ideal polar exist for a number of boats. However for each value they take into account configuration of the sails and a more efficient displacement configuration… (which also ? often run in practice).
      iPolar allows to vary these parameters as well as the user wishes and answer questions such: How can I lose to such a leg not using my spinnaker ?

      The second question is quite relevant. Performance analysis from data at sea to improve polars and various targets (heel, rudder, etc…) is one of our main activities. In this area we worked this year with teams that include Groupama, Camper, Macif, Poujoulat, Quantum Racing, WildOats… Once the connection established (we do understand that this does not have the most difficult) two obstacles to overcome :
      1) Calibration of electronic devices. If it is relatively easy to calibrate the speed, real wind is much more complex subject. It also faces a coupling phenomena such as heel and speed (this year 5% speed difference observed between 0 ° and 25 ° heel on a mini maxi…)
      2) Errors induced by the processing of instantaneous data : actually your boat will artificially excellent performance every time you leave a gust to enter into a calm. To handle this problem our professional tools for advanced data filtering to eliminate transitions.

      We are considering developing and delivering public iOS versions of these tools… work in progress as said !

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