4.1 Depending on the type and scope of programmes,
the acceptable tolerances should be determined differently, according
to 4.5 or 4.6. Excess from these tolerances should not be accepted
unless the Administration considers that there is a satisfactory explanation
for the difference and that there will be no adverse effect on the
safety of the ship.
4.2 Examples of pre-programmed input data include
the following:
-
.1 Hydrostatic data: displacement, LCB, LCF, VCB,
KMt and MCT versus draught.
-
.2 Stability data: KN or MS values at appropriate
heel/trim angles versus displacement, stability limits.
-
.3 Compartment data: volume, LCG, VCG, TCG and
FSM/grain heeling moments versus level of the compartment's contents.
4.3 Examples of output data include the following:
-
.1 Hydrostatic data: displacement, LCB, LCF, VCB,
KMt and MCT versus draught as well as actual draughts,
trim.
-
.2 Stability data: FSC (free surface correction),
GZ-values, VCG, GM, VCG/GM limits, allowable grain heeling moments,
derived stability criteria, e.g. areas under the GZ curve, weather
criteria.
-
.3 Compartment data: calculated volume, LCG, VCG,
TCG and FSM/grain heeling moments versus level of the compartment's
contents.
4.4 The computational accuracy of the calculation
program results should be within the acceptable tolerances specified
in 4.5 or 4.6, of the results using an independent program or the
approved stability information with identical input.
4.5 Programmes which use only pre-programmed data
from the approved stability information as the basis for stability
calculations should have zero tolerances for the printouts of input
data. Output data tolerances should be close to zero, however, small
differences associated with calculation rounding or abridged input
data are acceptable. Additionally differences associated with the
use of hydrostatic and stability data for trims that differ from those
in the approved stability information are acceptable subject to review
by the Administration.
4.6 Programmes which use hull form models as their
basis for stability calculations may have tolerances for the printouts
of basic calculated data established against either data from the
approved stability information or data obtained using the authority's
approval model. Acceptable tolerances should be in accordance with
the table below.
|
Hull Form Dependent
|
|
| Displacement
|
2%
|
| Longitudinal center of buoyancy, from
AP
|
1% / 50 cm max
|
| Vertical center of buoyancy
|
1% / 5 cm max
|
| Transverse center of buoyancy
|
0.5% of B / 5 cm
max
|
| Longitudinal center of flotation,
from AP
|
1% / 50 cm max
|
| Moment to trim 1 cm
|
2%
|
| Transverse metacentric height
|
1% / 5 cm max
|
| Longitudinal metacentric
height
|
1% / 50 cm max
|
| Cross curves of stability
|
50 mm
|
|
Compartment dependent
|
|
| Volume or deadweight
|
2%
|
| Longitudinal
center of gravity, from AP
|
1% / 50 cm max
|
| Vertical
center of gravity
|
1% / 5 cm max
|
| Transverse
center of gravity
|
0.5% of B / 5 cm
max
|
| Free surface moment
|
2%
|
| Shifting moment
|
5%
|
| Level of contents
|
2%
|
|
Trim and stability
|
|
| Draughts (forward, aft, mean)
|
1% / 5 cm max
|
| GMt
|
1% / 5 cm max
|
| GZ values
|
5% / 5 cm max
|
| FS correction
|
2%
|
| Downflooding angle
|
2°
|
| Equilibrium angles
|
1°
|
| Distance to unprotected openings or
margin line from WL, if applicable
|
± 5% / 50 mm
|
| Areas under righting arm curve
|
5% or
0,0012mrad
|
Deviation in % = {(base value - applicant's value)/base
value} ×100
The “base value” may be taken from the approved
stability information.