Most Common Mistakes

Here is a brief list of common mistakes with running MOSES:

  • Plotting to the Screen While Running a cif File:

    It you do this MOSES may "loose his mind". Screen actions are deferred until database I/O is performed. Now a screen picture alters the computational state and when the picture finishes, MOSES is lost. This can manifest itself in many strange ways.

  • Reading the model twice:

    Once with root.dat, and once with &device -auxin filename. This causes many problems, such as bad segment lengths on class definitions, and redefining points.

  • Using the wrong dimensions:

    Everyone remember the Mars lander that crashed due to a mixup between meters and feet? One technique that helps is to always use &dimen -save -dimen blength bforce and &dimen -remember as pairs at the beginning and end of every file that MOSES uses. This way the dimensions being used are documented and self contained within each file.

  • Forgetting to look for errors in your log and out files:

    Errors that occurred during the reading of the model are captured in the out file. You will need to use &device -oecho yes to see the actual input line where the error occurred. Other error messages are shown in the the .log file.

  • Forgetting to use -diftyp none for modeling appendages:

    such as skegs or rudders, will cause problems. Otherwise, the added mass and damping will be incorrect.

  • Neglecting to turn off load attributes for interior beams:

    For instance, if you have beams to model the structural properties of a barge model, you do not want these beams to attract buoyancy, wind or current load, since you will have a panel description for this.