little concern on Hydromax + looking for Span tutorials

Discussion in 'Software' started by Et', Mar 2, 2006.

  1. Et'
    Joined: Mar 2006
    Posts: 2
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    Location: uk

    Et' New Member

    Hello, I'm a french student in naval architecture (uk). I try to use the analysis of large angle stability on hydromax & after filling the loadcase I start the analysis but there is a window telling: 'try a less precise error values or more stations' :confused: => I've put 100 stations and the error values are at max..Is there some stages I've forgotten?:idea:
    Moreover is somebody have some tutorials for plotting polar diagram on Span?

    Thanks a lot. Regards. Bye
  2. Andrew Mason
    Joined: Mar 2003
    Posts: 397
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    Location: Perth, Western Australia

    Andrew Mason Senior Member

    The error message in Hydromax is saying that it is having trouble converging on an answer. This can be caused by discontinuities (e.g. appendages, chine flats, bow thrusters) in the hull shape affecting the programs prediction of step size when iterating to get equilibrium. This can be due to insufficient stations for the complexity of the hull, so I would try using 200 sections first.

    The problem can also be caused by very high trim angles (e.g. > 60 degrees) being used, check that your center of gravity is in the right location and that trim angles are reasonable.

    If you still have problems with it, please email it to me at

    Polar diagrams are created as standard output in SPAN, if you are not getting them when you perform analysis, make sure you have angles and speeds defined in the Wind Data dialog.
  3. fastfish666
    Joined: Feb 2006
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    Location: area 65

    fastfish666 New Member

    Another common thing that produces this dialog is that the displacement is too high and the vessel has sunk. Normally Hydromax will report such an error. I recommend you double check the vessel mass and CG as defined in the loadcase. You can do an upright hydrostatics or specified condition analysis at a draught which completely immerses the vessel to find out the maximum payload of the vessel. Also check the LCG you have specified (this is from the model zero point) the LCB results have the option of being reported from amidships or the zero point.

    Finally sometimes people forget to setup the positions of the fwd and aft perpendiculars in the _Maxsurf_ frame of reference dialog. This too can prevent Hydromax from converging on a result.
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