If you have to relocate the origin of the coordinate system, the biggest part of the task might be shifting a complex weight distribution. Part Maker makes it easy to shift the origin of the geometry using the SHIFT command, but there remains that multi-line WEIGHT command for the light ship distribution that has to be dealt with.

In case you haven't discovered this on your own,

SOLVE LCG

does not reduce light ship to a point at the new LCG; rather it shifts all the elements of your light ship distribution (not including ADD + items).

Here is how it works:

At a known attitude (heel, trim) as loaded, issue the command,

SOLVE DEPTH, LCG

Then to view the light ship distribution graph (in your active report):

WEIGHT REPORT /PROFILE

Before doing that, fixed-weight items must be relocated, which requires editing the ADD commands.

Here is an idea to make that task easier: Write a macro named ADD that issues the ADD command in the special form that shifts the L value. For example,

 MACRO ADD
  ADD "%1", *, *+{LSHIFT} /NOWARN
 /

Then place a dot before each ADD command to turn it into a macro call.

Since GHS version 15.52C this special form of the ADD command properly shifts weight distributions. (Formerly the distribution became a point.)

Any other commands that reference the longitudinal axis of the coordinate system must be edited independently (GROUND, PULL, THRUST, REF, CRTPT, LWL, LBP).

What follows is an example.

The status before the origin shift:

Click here to see the run file that produced the output shown above. It automates the conversion of the ADD commands to macro calls, so the whole thing runs without user intervention.

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