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


To check whether a vessel is operating within the limits imposed by stability criteria, GHS looks at certain properties of the righting-arm curve. Depending on the particulars of the criterion, it may evaluate things like range of stability, energy in that range, angle to downflooding, etc. The command that establishes numerical min/max limits on these properties is the LIMIT command.

A standard question everyone wants to know the answer to is how high the center of gravity can be and still meet stability requirements. Say at a given displacement, what is the highest VCG that passes all the limits?

There are cases with certain ships and certain criteria where surprising things happen as the VCG is raised. For example, the angle of trim might increase and immerse a weathertight point even at zero heel. The highest VCG in that case could pass all the limits in the criterion by a wide margin but fail when it is raised just a bit more.

John Bonn ran into one of these, and he found a clever way to fix it by adding LIMIT FLOODHT to his other limits. Click here to get his explanation which he was glad to pass on (and we hope he likes his new GHS baseball cap).

Questions, comments, or requests?
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