3.7.12 Load lines should be assigned to self-elevating
units as calculated under the terms of the 1988 LL Protocol. When
floating, or when in transit from one operational area to another,
units should be subject to all the conditions of assignment of that
Protocol unless specifically excepted. However, these units should
not be subject to the terms of that Protocol while they are supported
by the seabed or are in the process of lowering or raising their legs.
3.7.13 The minimum freeboard of units which due
to their configuration cannot be computed by the normal methods laid
down by the 1988 LL Protocol should be determined on the basis of
meeting applicable provisions regarding intact stability, damage stability
and structure in the afloat condition.
3.7.14 Where it is necessary to assign a greater
than minimum freeboard to meet intact or damage stability provisions
or on account of any other restriction imposed by the Administration,
regulation 6(6) of the 1988 LL Protocol should apply. When such a
freeboard is assigned, seasonal marks above the centre of the ring
should not be marked and any seasonal marks below the centre of the
ring should be marked. If a unit is assigned a greater than minimum
freeboard at the request of the owner, regulation 6(6) need not apply.
3.7.15 Where moonpools are arranged within the
hull in open communication with the sea, the volume of the moonpool
should not be included in the calculation of any hydrostatic properties.
If the moonpool has a larger cross-sectional area above the waterline
at 85% of the depth for freeboard than below, an addition should be
made to the geometric freeboard corresponding to the lost buoyancy.
This addition for the excess portion above the waterline at 85% of
the depth for freeboard should be made as prescribed below for wells
or recesses. If an enclosed superstructure contains part of the moonpool,
deduction should be made for the effective length of the superstructure.
Where open wells or recesses are arranged in the freeboard deck, a
correction equal to the volume of the well or recess to the freeboard
deck divided by the waterplane area at 85% of the depth for freeboard
should be made to the freeboard obtained after all other corrections,
except bow height correction, have been made. Free surface effects
of the flooded well or recess should be taken into account in stability
calculations.
3.7.16 The procedure described in paragraph 3.7.15
should apply in cases of small notches or relatively narrow cut-outs
at the stern of the unit.
3.7.17 Narrow wing extensions at the stern of
the unit should be considered as appendages and excluded for the determination
of length (L) and for the calculation of freeboards.
The Administration should determine the effect of such wing extensions
with regard to the requirements of the 1988 LL Protocol for the strength
of unit based upon length (L).
3.7.18 Self-elevating units may be manned when
under tow. In such cases a unit would be subject to the bow height
and reserve buoyancy requirements which may not always be possible
to achieve. In such circumstances, the Administration should consider
the extent of application of regulations 39(1), 39(2) and 39(5) of
the 1988 LL Protocol, as amended, and give special consideration to
such units, having regard to the occasional nature of such voyages
on predetermined routes and to prevailing weather conditions.
3.7.19 Some self-elevating units utilize a large
mat or similar supporting structure which contributes to the buoyancy
when the unit is floating. In such cases the mat or similar supporting
structure should be ignored in the calculation of freeboard. The mat
or similar supporting structure should, however, always be taken into
account in the evaluation of the stability of the unit when floating
since its vertical position relative to the upper hull may be critical.