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General HydroStatics
Ship Stability Software |
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Command of the Week
(New or interesting aspects of GHS that you may not know about) |
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Easy Light Ship
(Requires GHS version 17.00 or later) |
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"Light Ship" (meaning the weight and CG of the vessel unloaded) is a wide-ranging subject.
The only "Easy Light Ship" is one derived from drafts with a questionable VCG.
For hull bending calculations we need a longitudinal distribution too, which can be easy
if it is a rough approximation.
While the WEIGHT and ADD commands are not difficult to master, they are best used in Run Files. In order to avoid using a Run File to enter Light Ship, consider the DB EditLSWt command, which brings up a dialog: |
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| Click "Add new weight item" and the second layer appears: |
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Note that the Light Ship weight you would normally enter with the WEIGHT command
is denoted by /WEIGHT/ in the Data Base.
Enter the weight and CG numbers if you know them, or click the Calculate button to derive them from draft and trim as shown below. |
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| Showing the weight and LCG computed for the given draft and trim: |
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| To distribute this weight over the hull length, click "Segments." |
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| And then "Distribute". |
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| If a uniform linear distribution will suffice, use the "Distribute over length" button. Simply enter the overall length of the distribution to be centered at the LCG. |
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| Then Click Display for a quick graphical representation of the distribution range. |
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| Dropping back to the main dialog of the DB EditLsWt command, the /WEIGHT/ item appears with its numbers filled in. |
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Of course /WEIGHT/ is automatically stored in the Data Base associated with the
current Geometry File. Subsequently, whenever you want to get this light ship into the GHS calculation environment,
the command is DB GetLSWt which can be placed in your calculation Run File.
If you want to get into managing light ship variations, Data Base commands and dialogs are provided for that as well. But for this COW we are in the "Easy" mood. |
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Questions, comments, or requests?
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