Stability script for a basic stability software

Discussion in 'Boat Design' started by Surfer Naval Architect, Sep 1, 2019.

  1. Surfer Naval Architect
    Joined: Feb 2018
    Posts: 46
    Likes: 1, Points: 8
    Location: Amsterdam, The Netherlands

    Surfer Naval Architect Naval Architect

    Hello everyone,

    I would like to create a stability code in Excel or even better in Phyton/Matlab, I still have to decide which is the better tool to use in my case, I was wondering if you have any stability script that you can share in this forum.

    I would like to be able to calculate the hydrostatics, cross curves, downflooding points, righting levers.

    In particular for the larger angles, how do you get the GM and the BM angle by angle?


    Thank you in advance!
  2. Dolfiman
    Joined: Aug 2017
    Posts: 1,461
    Likes: 638, Points: 113
    Location: France

    Dolfiman Senior Member

    Within Gene-Hull, the GZ can be computed for the hull with heel, by introducing an angle and by manual iteration on the elevation and the trim up to the equilibrium (displacement = weight and Xc = Xg). It is a spreadsheet application developed under open office, and is open source : you can go in the administrator space ( from line 684) and modify what you want. The application are for sailing yachts, and presently the computation with heel can be done up to the immersion of the sheer line , so about 30°-35° (future extension is in mind to deal with all angles). That can help you to develop your own spreadsheet focused on that issue specifically, keep in mind that an accurate computation need to have a connection with the hull volume definition. Here are the spreadsheet and the user guide with full details
    Gene-Hull upgrade 2,3
  3. Ad Hoc
    Joined: Oct 2008
    Posts: 7,323
    Likes: 1,216, Points: 113, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    For large angle stability there is enough of a change in the WPA and volumes that render the small angle stability assumption no longer valid. Since the values of KM etc are no longer constant. There are several ways in which to achieve your objective.
    By simple cross curves of stability:

    or, by constructing a curve of metacentres:

    This gives you to data points you need.
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