4.9.2.1 The area under the righting lever curve
(GZ curve) should not be less than 0.009/C metre-radians up to θ
= 30° angle of heel, and not less than 0.016/C metre-radians up
to θ = 40° or the angle of flooding θ f (as
defined in 3.1.2) if this angle is less than 40°.
4.9.2.2 Additionally, the area under the righting
lever curve (GZ curve) between the angles of heel of 30° and 40°
or between 30° and θf, if this angle is less
than 40°, should not be less than 0.006/C metre-radians.
4.9.2.3 The right lever GZ should be at least
0.033/C m at an angle of heel equal or greater than 30°.
4.9.2.4 The maximum righting lever GZ should be
at least 0.042/C m.
4.9.2.5 The total area under the righting lever
curve (GZ curve) up to the angle of flooding θf should
not be less than 0.029/C metre-radians.
4.9.2.6 In the above criteria the form factor
C should be calculated using the formula and figure 4.9-1:.
|
C |
= |
|
|
D' |
= |
moulded depth
of the ship, corrected for defined parts of volumes within the hatch
coamings according to the formula: |
|
D |
= |
moulded depth
of the ship in m; |
|
BD
|
= |
moulded
breadth of the ship in m; |
|
KG |
= |
height of the
centre of mass above base, corrected for free surface effect, not
be taken as less than d, in m |
|
Cw |
= |
waterplane coefficient. |
|
l
H
|
= |
length of each hatch coaming within L/4 forward and aft from
amidships, in m (see figure 4.9-1);
|
|
b |
= |
mean width of
hatch coamings within L/4 forward and aft from amidships, in m (see figure 4.9-1);
|
|
h |
= |
mean height of
hatch coamings within L/4 forward and aft from amidships, in m (see figure 4.9-1);
|
|
L |
= |
length of the
ship, in m; |
|
B |
= |
breadth of the
ship on the waterline, in m; |
|
Bm
|
= |
= breadth of the ship
on the waterline at half mean draught, in m. |
The shaded areas in figure 4.9-1 represent partial volumes within the hatch coamings considered
contributing to resistance against capsizing at large heeling angles
when the ship is on a wave crest.
Figure 4.9.1