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

Hull bending, or deflection as it is called, can have a significant effect on drafts
compared to ideal drafts with no bending. If the deflection is known, the
DEFLECT command is a convenient way to correct for this. After applying deflection,
the displacement derived from drafts will be more accurate.
It's no secret that GHS accounts for deflection by bending the waterplane, not the hull model. To illustrate this, here is a ridiculously large hogging deflection: 
DEFLECT 4.0 
Imagine what this would do to the coordinate system (which is tied to the ship)
if the geometry were somehow bent!
Since bending is usually small compared to the length of the vessel, an acceptable approximation of the deflection effect is obtained by a secondorder or parabolashaped curve applied to the waterplane. Here is a more reasonable amount of deflection: 
DEFLECT 0.25 
To correct displacement and LCG respecting the deflection: 
SOLVE WEIGHT, LCG
STATUS 
In practice, the DEFLECT command takes a back seat to the DRAFT command in which a series of drafts can be given from which deflection is calculated. 
DRAFT 7.0 @ 45F, 6.75 @ 0. 7.0 @ 45A
SOLVE WEIGHT, LCG STATUS 
Here is the screen output comparing the result of the DEFLECT command with the result of the 3point DRAFT command. 
Deflection can also be calculated using
the Longitudinal Strength feature in GHS.
The system variable DEFLECT can be used to capture whatever deflection has been calculated into another variable so it may be restored later by the DEFLECT command. It is important to know the length over which deflection is referred. The full syntax of the DEFLECT command allows for specifying a length. To keep this COW simple we will leave deflection lengths to the GHS manual and the GHS training class. 
Questions, comments, or requests?
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