2.5 Intact stability calculation
The mass and centre of gravity of the whole system are input for the intact stability calculation. For this tutorial a very simplified stability calculation is used. The only input value that is required is the moment of area inertia of the waterline area.
- Create a new class in the Knowledge Browser alongside the others that you have made so far:
Intact stability calculation.
- Create the following parameters in the Knowledge Browser:
Parameter name | Dimension | Determined by | Reference | In Class |
BM | [m] | USR: User or system/equation | Distance between center of buoyancy and metacenter | Intact stability calculation |
GM | [m] | USR: User or system/equation | Metacentric height | Intact stability calculation |
KB | [m] | USR: User or system/equation | Distance between keel and center of buoyancy | Intact stability calculation |
KG | [m] | USR: User or system/equation | Distance between keel and center of gravity | Intact stability calculation |
Moment_of_Inertia | [m^4] | USR: User or system/equation | Moment of inertia of the water plane area in m^4, For this tutorial give a rough estimate | Intact stability calculation |
- Include the
...
- following parameters inentity
Intact stability calculation
...
- :
...
Loa
...
- ,
...
Boa
...
- ,
...
BM
...
- ,
...
COGX
...
- ,
...
COGY
...
- ,
...
COGZ
...
- ,
...
Displacement
...
- ,
...
GM
...
- ,
...
KB
...
- ,
...
KG
...
- ,
...
Moment_of_Inertia
...
- ,
...
Rho
...
- ,
...
- and
T_design
...
- .
- Create the following relations (either
...
- entity relations or normal relations,
...
- it does not matter here):
Loa = ENTITY#(xx).Loa
...
where “xx” is the
...
QEntityID value of
...
entity Main Dimensions
...
.
Boa = ENTITY#(xx).Boa
...
where “xx” is the
...
QEntityID value of
...
entity Main Dimensions
...
.
GM = KB + BM – KG
BM = Moment_of_Inertia / (Displacement/Rho)
KG = COGZ
KB = 0.7*T_design
T_design = ENTITY#(xx).T_
...
design where “xx” is the
...
QEntityID value of
...
entity Hydrostatics
...
.
Displacement = ENTITY#(xx).Mass
...
where “xx” is the
...
QEntityID value of
...
entity Mass calculation
...
.
COGX = ENTITY#(xx).COGX
...
where “xx” is the
...
QEntityID value of
...
entity Mass calculation
...
.
COGY = ENTITY#(xx).COGY
...
where “xx” is the
...
QEntityID value of
...
entity Mass calculation
...
.
COGZ = ENTITY#(xx).COGZ
...
where “xx” is the
...
QEntityID value of
...
entity Mass calculation
...
.
Rho = ENTITY#(xx).Rho
...
where “xx” is the
...
QEntityID value of
...
entity Hydrostatics
...
.
- To show computed values during a dialogue write “@SHOW” behind “QEntityData”set attribute @SHOW on
QEntityData.
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