"SA-VPP Sailboat", a free application for speed prediction

Discussion in 'Software' started by Dolfiman, Oct 12, 2020.

  1. Dolfiman
    Joined: Aug 2017
    Posts: 1,165
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    Location: France

    Dolfiman Senior Member

    « SA-VPP Sailboat » is a spreadsheet application about the prediction of the sailboat speed and heel angle for 3 typical sailing conditions, by wind 4 to 20 Knots :

    1. - Upwind on calm water
      - Beam reaching, twa 90°
      - Downwind with spi, twa 135°
    The main goal is to provide a help tool to optimise a project at its early stage about the performance objectives, able to show and to quantify in terms of boat speed the influence of such or such parameter and so to guide the project towards an optimum. The input consists of a relatively short list of data (33 exactly) representative of the hull, the appendages (keel, bulb, rudder), the displacement, the sailplan, the righting moment, the wetted surface. The ouput are the speed curves with wind force for these 3 sailing conditions, as also the heel angles and the drag curves. The Reef parameter is an input, so you can use it to fastly test various sailplan area option.

    The residuary drag component is based on the Delft series and derived empirical formulations. These series are dated from the 70's and 80's , so probably that the planing ability and corresponding speed of recent light beamy sailboats, when beam reaching or downwind with sufficient wind, are underrated by SA-VPP. I can improve on that point as long as I can catch reliable data on publications.

    It is a free and open source speadsheet application, developed on a support itself free and widespread (Open Office Calc 4.0.1) : to open and use an ods file, you have to download Open Office or Libre office according to : ODS File Extension - What is an ods file and how do I open an ods file? | OpenTheFile http://www.openthefile.net/extension/ods

    This application can be used stand alone, in complement to any other software used for the project development and providing the necessary data. For the User of « Gene-Hull Sailboat » application, an adapted version 3.1 (also attached) was developed which helps prepare the set of input data for « SA-VPP » : once fulfilled, you have then just to copy/paste the set towards the VPP application.

    In the User Guide attached, you will find all information necessary to prepare this set of data, whatever their upstream source. In complement, a technical annex is proposed with all the formulations and algorithms involved for those interested to know the basis of this prediction program.

    Also attached an Examples document of input/output data for 4 different sailboats.

    By hoping this can be helpful for your project.

    Attached Files:

    petit bateau likes this.
  2. petit bateau
    Joined: Nov 2012
    Posts: 8
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    Location: Dorset

    petit bateau Junior Member

    Thank you very much Jean-Francois / Dolfiman. These are the formulations you developed when working on the Corbin 39 project (= Blue Water 39) which has several different sailplans. As you know we were able to relate them quite well to reported performance of the different sailplans. They are now presented in a more generally accessible format for wider use. What you have put together here are a set of very effective and powerful software analysis tools that would be a credit to many professional for-profit software design houses, and which you are most generously sharing with the community for free. I hope that they are taken up by the community and I think you have done an absolutely fantastic job for us all. In short I highly recommend these tools of yours.

    Many thanks, both for your assistance on the Corbin 39 / Blue Water 39 project, and for so generously sharing all this with everyone.

    regards, ds/pb
  3. Dolfiman
    Joined: Aug 2017
    Posts: 1,165
    Likes: 502, Points: 113
    Location: France

    Dolfiman Senior Member

    Many thanks David / petit bateau for your kind words, I do appreciated to work with you on this issue for the Corbin 39 and I think we have made progress together.
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