3.2.1 SOLAS Ch. II-1 Reg. 9 contains a number of clauses the majority of which are explicit
in their requirements. However, there are also clauses which would benefit from
further consideration. These are discussed in the following paragraphs.
3.2.2 SOLAS Ch. II-1 Reg. 9.1 mandates that a double bottom will be fitted
throughout the full length of the vessel (collision BHD to afterpeak BHD), or as far
as is reasonably practicable. The key aspect here is the definition of ‘reasonably
practicable’. In essence, if the form or arrangement of the vessel, its equipment or
components or its operational profile precludes the ability to fit a suitable double
bottom of the extent required, then a written exemption should be provided by the
Flag State. Should an alternative arrangement be agreed between the designer or
builder and the Flag State, then details of that agreement should be passed to LR
for consideration at the plan approval stage.
3.2.3 SOLAS Ch. II-1 Reg. 9.3 is explicit. However, it allows variation for ‘other wells’.
In such cases, the proposed arrangements are to be assessed for an equivalent level
of safety by the Flag State. Where an exemption is agreed between the designer or
builder and the Flag State, then details of that exemption should be passed to LR
for consideration at the Plan Approval stage.
3.2.4 SOLAS Ch. II-1 Reg. 9.5 presents an option for exemption to the requirement to fit a
double bottom to passenger ships traveling within the limits of ‘short international
voyages’ and that are employed in the carriage of ‘special trade passengers’. This
regulation is similar to that in SOLAS Ch. II-1 Reg. 9.1 in that it allows the
administration to accept alternative double bottom arrangements where those
stipulated in SOLAS are impractical to apply. However, if this exception is to be
applied, the vessel must comply fully with the provisions of both:
- the rules annexed to the Special Trade Passenger Ships Agreement, 1971;
and
- the rules annexed to the Protocol on Space Requirements for Special Trade
Passenger Ships, 1973.
Where an exemption is agreed between the designer or builder and the Flag State, then
details of that agreement should be passed to LR for consideration at the Plan
Approval stage.
3.2.5 SOLAS Ch. II-1 Reg. 9.7 is particularly applicable to SSC vessels as it requires that
vessels with ‘unusual bottom arrangements’ are required to demonstrate compliance
with the damage stability criteria when subjected to bottom damages. If one
considers that in the context of SOLAS, usual bottom arrangements are those seen on
typical tankers, i.e. Long parallel mid bodies and substantial flat of side and flat
of bottom tapering in, for the bow and stern. This is not the typical arrangement
seen in SSC vessels. As such, SSC vessels will generally be required to comply with
the damage stability criteria contained in SOLAS Ch. II-1 Reg. 9.8. However, it does
permit a significant level of flexibility in the design, negating the preceding
prescriptive regulations relating to double bottom extent.
3.2.6 It is worth noting that SOLAS Ch. II-1 Reg. 9.6 stipulates that where an exemption is
given under SOLAS Ch. II-1 Reg. 9.1, 9.4, or 9.5, it is required that the absence of
strakes of double bottom does not affect the damage stability compliance of the
vessel, i.e. does not reduce si to less than 1 for bottom damages
(calculation of si is detailed in SOLAS Ch. II-1 Reg. 7.2).
Therefore, in the absence of Flag State specific requirements, where SOLAS is to be
applied, even where exemptions for the extent of a double bottom are granted, damage
stability compliance is to be demonstrated.