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 |
| [m] | USR: User or system/equation | Distance between center of buoyancy and metacenter | Intact stability calculation |
| [m] | USR: User or system/equation | Metacentric height | Intact stability calculation |
| [m] | USR: User or system/equation | Distance between keel and center of buoyancy | Intact stability calculation |
| [m] | USR: User or system/equation | Distance between keel and center of gravity | Intact stability calculation |
| [m^4] | USR: User or system/equation | Moment of inertia of the water plane area, For this tutorial give a rough estimate | Intact stability calculation |
- Include the following parameters in entity
Intact stability calculation
:Loa
,Boa
,BM
,COGX
,COGY
,COGZ
,Displacement
,GM
,KB
,KG
,Moment_of_Inertia
,Rho
, andT_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 set attribute @SHOW on
QEntityData
.