Compulsory Information
SPECIAL NOTES
- Calculation of the wind heeling arms:
In the case of the wind pressure based formulation, the wind heeling arm is given by:
H w ( ) = a
PA(h − H ) n
cos ( )
g
where:
a is a constant, theoretically unity
A is the windage area at height h
 is the vessel mass
P is the wind pressure
H is the vertical centre of hydrodynamic resistance to the wind force
In the case of the wind velocity based formulation, the wind heeling arm is given by:
H w ( ) = a
v 2 A(h − H ) n
cos ( )
g
where:
a is now effectively an average drag coefficient for the windage area
v is the wind speed.
And the other parameters are described as above.
Option
Description
constant: a
Constant which may be used to modify the magnitude of the
heel arm, normally unity
wind model
Pressure or Velocity (type “P” or “V”)
wind pressure or velocity
Actual velocity of pressure - depends on wind model
Units
Pa or
length/
time
area centroid height: h
Height of user defined total or additional windage area
length
total area: A
User may specify either a total windage area
length2
additional area: A
Or, an area to be added to the windage area computed by
Hydromax based on the hull sections
length2
height of lateral resistance: H
There are four options for specifying H (all options are
calculated with the vessel upright at the load case
displacement and LCG):
length
User specified
H = mean draft / 2
H is taken as half the mean draft.
length
H = vert. centre of projected lat.
u'water area
H is taken as the vertical centre of underwater lateral projected
area.
length
H = waterline
H is taken as the waterline
length
cosine power: n
Cosine power for curve - defines shape
2