Hull and Stability

Pt B, Ch 3, Sec 1
3 Examination procedure
3.1 Documents to be submitted
3.1.1 List of documents (1/10/2005)
For the purpose of the examination of the stability, the documentation
listed in Ch 1, Sec 3, [1.1.2] is to be submitted
for information.
The stability documentation to be submitted for approval, as
indicated in Ch 1, Sec 3, [1.2.1], is as follows:
a) Inclining test report for the ship, as required in [3.2] or:
where the stability data is based on a sister ship, the
inclining test report of that sister ship along with the
lightship measurement report for the ship in question;
or
where lightship particulars are determined by methods
other than inclining of the ship or its sister, the
lightship measurement report of the ship along with
a summary of the method used to determine those
particulars as indicated in [3.2.4].
b) trim and stability booklet, as required in Sec 2, [1.1.1]
c) and, as applicable:
grain loading manual, as required in Pt E, Ch 4,
Sec 3, [2.2.2]
loading computer documentation, as required in
Sec 2, [1.1.2] and in Pt F, Ch 13, Sec 11, [2.1.2].
A copy of the trim and stability booklet and, if applicable,
the grain stability booklet or the loading computer documentation
is to be available on board for the attention of the
Master.
3.1.2 Provisional documentation
The Society reserves the right to accept or demand the submission
of provisional stability documentation for examination.
Provisional stability documentation includes loading conditions
based on estimated lightship values.
3.1.3 Final documentation
Final stability documentation based on the results of the
inclining test or the lightweight check is to be submitted for
examination.
When provisional stability documentation has already been
submitted and the difference between the estimated values
of the lightship and those obtained after completion of the
test is less than:
2% for the displacement, and,
1% of the length between perpendiculars for the longitudinal
position of the centre of gravity,
and the determined vertical position of the centre of gravity
is not greater than the estimated vertical position of the centre
of gravity, the provisional stability documentation may
be accepted as the final stability documentation.
3.2 Inclining test/lightweight check
3.2.1 Definitions
a) Lightship
The lightship is a ship complete in all respects, but without
consumables, stores, cargo, and crew and effects,
and without any liquids on board except for machinery
and piping fluids, such as lubricants and hydraulics,
which are at operating levels.
b) Inclining test
The inclining test is a procedure which involves moving
a series of known weights, normally in the transverse
direction, and then measuring the resulting change in
the equilibrium heel angle of the ship. By using this
information and applying basic naval architecture principles,
the ship's vertical centre of gravity (VCG or KG)
is determined.
c) Lightweight check
The lightweight check is a procedure which involves
auditing all items which are to be added, deducted or
relocated on the ship at the time of the inclining test so
that the observed condition of the ship can be adjusted
to the lightship condition. The weight and longitudinal,
transverse and vertical location of each item are to be
accurately determined and recorded. The lightship displacement
and longitudinal centre of gravity (LCG) can
be obtained using this information, as well as the static
waterline of the ship at the time of the inclining test as
determined by measuring the freeboard or verified
draught marks of the ship, the ship's hydrostatic data
and the sea water density.
3.2.2 General (1/1/2009)
Any ship for which a stability investigation is requested in
order to comply with class requirements is to be initially
subject to an inclining test permitting the evaluation of the
position of the lightship centre of gravity so that the stability
data can be determined.
The inclining test or lightweight check (see [3.2.4]) is to be
attended by a Surveyor of the Society. The Society may
accept inclining tests or lightweight checks attended by a
member of the flag Administration.
For cargo ships having length less than 24 metres, irrespective
of their navigation, at the discretion of the Society,
instead of the inclining test one or more practical stability
test(s) relevant to the most severe conditions foreseen in real
service may be carried out.
In such cases a report is to be prepared relevant to the
tested loading conditions containing restrictions in the loading
conditions and/or in ballasting, if any, which, duly
approved by the Society, is to replace the prescribed stability
booklet.
44 RINA Rules 2012