General HydroStatics
Ship Stability Software
Command of the Week
(New or interesting aspects of GHS that you may not know about)


The real-world generally does not offer do-overs when we make mistakes. But in the world of bytes, software permits certain types of do-overs with little to no penalty. For example, there's spell check or the undo function in Section Editor (Control-U).

FIXUP in GHS is an elegantly simple and effective command that performs corrective modifications on a geometry file automatically, thus allowing the user to get back to work immediately.

The solution to a great many problems, FIXUP quickly handles one of the most common geometry errors, "Section spacing too great ..." Even though the error message tells us the location, shape and component where the error occurs, why delve into the nitty-gritty details of the geometry realm when a single word FIXes the problem?

In its basic form, simply typing FIXUP at the command prompt is like waving a magic wand at the erroneous geometry file. While there are several useful parameters associated with FIXUP, by default, it automatically performs the following operations on all components in the file:

  • Clockwise loops are detected and corrected.
  • Redundant points and intermediate points on straight lines are removed.
  • Component and part records are ordered correctly in the Geometry File.
  • Component names are capitalized (except when a single character is followed by a number)
  • Duplicate parts are deleted.
  • Components with zero effectiveness are deleted and noted.
  • HULL\HULL.C is FILLed if necessary, solving our dreaded section spacing error.

Next time you get an error when reading a Geometry File, wave away the pesky problem with FIXUP. You might find that it even helps with station interpolation. It does this by reordering points on closed loop centerline shapes such that the starting points are in a uniform location, usually closest to centerline. If you have any doubt about the changes FIXUP made to your hull after reading the output screen, a quick look in Section Editor is good assurance.

P.S. - Don't worry, a backup copy of the original GF file is created in case luddite tendencies emerge and you prefer to fix your own mistakes.

Questions, comments, or requests?
Contact Creative Systems, Inc.

USA phone: 360-385-6212 Fax: 360-385-6213
Office hours: 7:00 am - 4:00 pm Pacific Time, Monday - Friday

Mailing address:
PO Box 1910
Port Townsend, WA 98368 USA

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