3.1.1 Plans and calculations are to be submitted, as necessary, to amplify and
verify the specifications, to LR’s satisfaction. The plans and calculations will
depend on the design and purpose of the submersible or chamber but will generally
include the following where applicable:
- Chamber or hull strength.
- Accelerations and dynamic loads.
- Resistance and propulsion loads, powers and reactions.
- Main and auxiliary power requirements.
- External loads due to external pipings, external attachment and
loading resulting from acceleration referred to in Pt 3, Ch 1, 2.4 Sea transport design requirements 2.4.1, including loads e.g. trunking
load, expansion, wind.
- Deck deflections as applicable.
- Fatigue assessment due to pressure cycles / external (acceleration) cyclic
loads based on wave scatter data of the region. Wave scatter data from a
recognised source should be used.
- Cradle or support design and arrangement.
3.1.2 The calculation procedure proposed for determining the scantlings of the
pressure chamber or hull, or its equivalent, is to be submitted for consideration at
an early stage and the derived calculations, and conclusions drawn there from, are,
where practicable, to be submitted for scrutiny before construction Of the
submersible is commenced.
3.1.3 Where computers are used for calculations, LR is to be satisfied as to
the capability, accuracy and reliability of the software programs used and of the
arrangements used to verify input data before processing.
3.1.4 Calculations of pressure chamber or hull stresses are, where practicable,
to take into account the interaction of the pressure chamber or hull with attached
hatches, windows, rigid fixtures, mechanical components and hull penetrations, etc.,
with particular reference to the possibility and effect of stress flow distortions
due to constructional details and techniques and to pressure at various depths of
submergence.
3.1.5 The drawings of a pressure chamber or hull are to show clearly all
relevant dimensional tolerances including permissible out-of-roundness and local
departures from shape. The design calculations should take account of the
combination of the most unfavourable tolerances.
3.1.6 In calculating the scantlings of isobaric chambers, including the
attachments and fastenings of access hatches, windows and viewing ports,
consideration is to be given to the possibility of accidental pressurization of the
chamber in the reverse sense to that used for the basic design. The differential
pressure used in the design calculations for this eventuality should not be less
than two atmospheres unless especially agreed otherwise by LR.
3.1.7 When dynamic loads are being calculated, and use is being made of
statistical methods, LR may require an increased load factor if the available
statistical data is considered to be insufficient or unreliable.
3.1.8 The type and sophistication of the calculations will depend on the
design, materials and purpose of the components under consideration, and it is
anticipated that for many items computers will be used for stress analysis.
Designers are free to submit, for consideration calculations based on design
philosophies other than those given in Pt 3, Ch 1, 3.1 General 3.1.1 and Pt 3, Ch 1, 3.1 General 3.1.3.
3.1.9 Where applicable, for habitats on the sea bed, the design of sea bed
mounting is to be carefully considered and all external parts shall be faired to
prevent snagging.
3.1.10 The whole concept is to be designed with a view to access and
maintenance.