Feature request for stability calculations

  • Nobody/Anonymous

    Martijn, this new stability calculation module is great! Freeship is almost perfect now it includes stability calculations.

    it would however be helpfull to have somthing like multisurf to automaticaly close te model (ad a deck and transom)or to have a wizzard for this just like keel and rudder.
    It would also be very helpfull to have a option to calculate "critical points" or downflooding points. Modern stability standards such as STIX etc have requirements for this.

    is there any way the comunity can contribute with the development of this program?



    • Nobody/Anonymous

      This downflooding angle calculation would be very much appriciated as it enables stabiliticalculations according ISO 12217 amongst others.

      Could you please add this freature to one of the future versions of this already amazing program Martijn??

      thanks and regards,

      • Marven

        Marven - 2006-05-08

        I'll try to add this in the next release, but I'm not sure it will be finished by then. In fact are the "leak points" also an implementation of this. There's no need to specify a margin line anymore since the program can determine by itself when the sheerline is being submerged and water enters the hull. But I agree that additioal downflloding points (and markers that indicate when other parts of the model become submerged) are a useful asset.

    • Nobody/Anonymous

      Thak you very much for all your effort. It is greatly appreciated. Freeship is almost the most perfect hull design and hydrostatic claculation   program now.

      thanks again

    • antoine

      antoine - 2006-05-09

      Hi everybody,
      It's fun, but I just asqued me last minut where I could find the ISO 12217 - 3 norm in order to declare my boat ( canot540 in drawings database) at the french institutions.  Could someone help me to find this norms ? thanks a lot, Antoine


    • Nobody/Anonymous

      these standards are copyrighted by ISO. Therfore you can not find them on the internet. Normaly you should buy these standards at the national standarization institute.

      • Nobody/Anonymous

        these rules make the law, and so the law is based on ISO... but ISO is private and u must pay to know it !
        at least in France, probably in all European countries, this law is not free :(

    • Nobody/Anonymous

      ISO is not law. it is the prefered way of proving the provisions of the law are complied to. Other means may also be acceptable but this is not recommended and this may be subject to further evaluation by a notified body.

      www.ecb.nl or www.rsg.be contain usefull info

    • Nobody/Anonymous

      Really great software!!! Stability calculations in FreeSHIP was a really big leap...

      However, I'm more used to reading GZ-curves than cross-curves... any possibility that you could add GZ-curves as an option when calculating/presenting stability? (I guess one would be prompted to input VCG... )

      thanks and regards, Kim

      • Marven

        Marven - 2006-05-31

        That's correct. It will be in release 2.7

    • antoine

      antoine - 2006-05-31

      Great, I enjoy to see it ! Antine

    • Nobody/Anonymous

      I guess you guys are refering the the intact stability. How about the dymanic stability, with all the weight, liquids, cargo, and different voyage condition? Any way to implement this in the next version? thanks for your reply

      • Marven

        Marven - 2006-10-04

        The professional version of FREE!ship that comes out later this month includes tank modeling and loadcases (including shift of COG of liquids, free surface moments, dyn. stability etc.). This functionality is not for free however.

    • dansherman

      dansherman - 2006-10-04


      Do you have a projected cost for Freeship pro?

    • Nobody/Anonymous

      Preliminary stability calculation.
      Free!ship provides means to give weights to surface panels, and calculates the center of gravity for these panels.

      For a sailing boat design there are substantial weights like the keel, engine and
      mast. If one could assign weights and center of effort to these, it could be easy to tabulate them together with the panels and calculate the (static)trim and righting moment.

      I know you are working with a full model with variable cargo weights and liquid surfaces.
      This kind of preliminary tool might help already in development of output display.

      Lauri Levanto


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