General HydroStatics
Ship Stability Software |
Command of the Week
(New or interesting aspects of GHS that you may not know about) |
CRITPT /INSIDE (review)
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When the hull is damaged, generally a secondary barrier is exposed; but such bulkheads may have
openings in them through which "progressive flooding" may occur.
To conveniently model this without having to constantly activate and deactivate critical points,
GHS provides a way to indicate that a critical point is of no account unless a particular compartment
is flooded.
Here is a simplified example of heeling up to the point of downflooding: |
CRITPT "Engine room air intake" 35.0, 10.0, 14.0 /TANK: VENTDUCT.S CRITPT "Vent to engine room" 35.0, 6.5, 10.0 /INSIDE: VENTDUCT.S MACRO InclineToFlood HEEL 0 RA /STOP:FLD /HOLD /GRAPH:NONE DISPLAY (*) STATUS body@35.0 /YesEmpty / .InclineToFlood |
Now look what happens if we run the same thing with VENTDUCT.S flooded: |
TYPE (VENTDUCT.S) FLOOD .InclineToFlood |
If you want to
model actual flows through openings the /OPENING:size parameter will do that
in conjunction with LOAD FLOW—for the benefit of salvage engineers
at least.
Critical points can do other things too: they are not restricted to representing downflooding points. Another common application is to mark weathertight openings, which have closures preventing flooding when intermittently immersed. We call these "Tight" points for brevity. You can easily move a critical point up or down by a given amount relative to the current waterplane without having to calculate the new coordinates. Then if you would like to get access to those new coordinates, the /ACCESS parameter gives you a way to load those values into your own variables. And there is a /SYMM parameter that automatically generates the mirror image of your critical point on the opposite side of the ship. Oh, yes, if you arrange critical points along a coaming you can get your reference point for flooding or spilling to relocate automatically to the lowest one. We could go on raving about the CRITPT command till the cows come home. It's enough to make you wish for the days when they did damage stability with reduced permeability instead of runoff and called it good—and when salvors did their calcs on the back of an envelope. |
Questions, comments, or requests?
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