| The CRTPT Command
GHS maintains a list of "Critical
Points" which are not associated with any particular part of
the vessel model, but are used as points of downflooding and other
purposes relating to the vessel as a whole. Critical points may
be specified through Part Maker in the model-building stage. They
may also be specified and changed with the main program.
A Critical Point consists of a name and a location (longitudinal,
transverse and vertical coordinates). It also has two additional
attributes: Symmetry status and Flooding status.
The Symmetry status of a Critical Point indicates whether the point
is to be regarded as the single point represented by its coordinates
(asymmetrical) or as actually two points, one symmetrically opposite
the other (by negation of the transverse coordinate). By default
the Symmetry status is asymmetrical. To make it symmetrical the
following form of the
CRTPT command is used (in the Main Program, not Part Maker):
CRTPT ... /SYMMETRICAL
Any use of a critical point which implies only one point (eg. the
HEIGHT command) uses only the point as given and ignores the Symmetry
status.
The Flooding status has three states: Flooding, Tight and Noflooding.
Flooding means that the point will be regarded as a downflooding
point as referenced by the FLD keyword in the LIMIT command and
the DAMSTAB command.
Tight is similar to flooding but it applies only when the vessel
is at the initial equilibrium angle. At other heel angles the Tight
critical points are considered to be nonflooding.
Noflooding means that the critical point is ignored as a flooding
point.
The Flooding status can be set in the main program by appending
one of the parameters
/FLOOD, /TIGHT
or
/NOFLOOD
to the CRTPT command. The default is Flooding.
The FLDPT Command
The FLDPT command works in conjunction with the CRTPT command.
It allows the Flooding status of any or all Critical Points to be
conveniently changed. It has the following form:
FLDPT [(n)] ON | OFF [/TIGHT]
n refers to one of the Critical Points.
If it is absent, all Critical Points are implied.
ON turns on the Flooding status (Flooding or Tight, depending
whether the /TIGHT parameter appears).
OFF sets the Flooding status to Nonflooding.
Effects of Flooding and Tight Critical Points
RA, MAXVCG and SOLVE MAX
commands
The procedure invoked by these commands in turn refers to the stability
criterion defined by LIMIT commands. When the FLD keyword is referenced
by a LIMIT, it implies the downflooding points represented by Critical
Points with Flooding status either Flooding or Tight. However, any
Tight Critical Points are only considered when the vessel is in
equilibrium.
The CC Command
This command considers only Critical Points having Flooding
status.
The DAMSTAB Command
Like the RA command, DAMSTAB considers Critical Points having
both Flooding and Tight status, but the Tight points are ignored
except at the initial equilibrium.
The DIVISION Command
The DIVISION command can
reference a Critical Point when the /FLD parameter is used.
For example, DIVISION ... /FLD:
2 associates Critical Point 2 with the division when it is being
defined. It also sets the Critical Point to Flooding status in case
it was not so designated before. When a Critical Point is associated
with a division in this manner it prevents that point from being
considered when that division is flooded during the DAMSTAB command
process.
NOTE: MAXVCG, SOLVEMAX, DAMSTAB and DIVISION are not available in
BHS or BHS/Yacht.
CC is not available in BHS/Yacht. |
