4.1.2 Overall subdivision of the hull should take full account of strength and
stability requirements and minimise the consequences of damage, pollution risk and
loss of the unit in the event of damage. Additional subdivision of the hull may be
required to account for ballast water needed to control hull stresses and for the
storage of process-related liquids.
4.1.3 The Marine Environment Protection Committee of the International
Maritime Organization (IMO) has decided that tankers which are used solely for
storage and production of oil, and are moored at a fixed location except in extreme
environmental or emergency conditions, are not required to comply with all the
provisions of the International Convention for the Prevention of Pollution from
Ships, 1973, as modified by the Protocol of 1978 relating thereto
(hereinafter referred to as MARPOL) unless specified in whole or in part by the
relevant National Authority. Therefore, double hulled construction would not be
necessary unless specified by the National Authority. When MARPOL is invoked for
ship units, normally also the interpretations for ship units defined in MEPC Circ.
311(73) are applicable, but this is subject to adoption of MEPC Circ.311(73) by the
National Authority.
4.1.4 Account should be taken of the interaction between structural strength
and stability. Particular consideration should be given to tank dimensions with
respect to tank inspection/ maintenance requirements and sloshing/free surface
effects for partially filled tanks. Intact and damage stability should comply with
applicable National Authority requirements.
4.1.5 Self-propelled floating units should meet the requirements of the
International Convention on Load Lines 1966 (hereinafter referred to as
ICLL). Units which do not engage in international voyages, except for transfers
between fabrication sites and the installation voyage to the designated site, should
have marks which indicate the maximum permissible draught as calculated under the
ICLL Requirements.
4.1.7 Deck-house superstructures may be located forward or aft of the cargo
storage tanks. Living quarters, lifeboats and other means of evacuation should be
located in non-hazardous areas and be protected and separated from production,
storage and turret areas. As a minimum, the arrangement and separation of living
quarters, storage tanks, machinery rooms, etc. should be in accordance with the
International Convention for the Safety of Life at Sea, 1974 and its
Protocol of 1978 (hereinafter referred to as SOLAS). Where the superstructure is
located forward of the cargo tank area, arrangements should provide a suitable level
of separation and protection.
4.1.8 The location of the topsides facilities deck and structural arrangements
should comply with Pt 3, Ch 3, 3.1 General 3.1.4, Pt 3, Ch 3,7 and Ch 3,8 and Pt 7 Safety Systems, Hazardous Areas and Fire as relevant, together with applicable National Authority
Codes and Standards regarding dangerous zones or divisions and provision of adequate
access. Areas and compartments of floating units are defined as hazardous zones
according to their proximity to equipment, pipes or tanks containing certain
flammable liquids and whether these fluids are at temperatures approaching or
exceeding their flashpoints, see
Pt 7, Ch 2 Hazardous Areas and Ventilation.
4.1.9 Alternative arrangements which are proposed as being equivalent to the
Rules will receive individual consideration, taking into account any relevant
National Authority requirements.
4.1.10 Reference should also be made to SOLAS and applicable amendments.
4.1.11 The number of openings in watertight bulkheads is to be kept to a
minimum. Where penetrations of watertight bulkheads and internal decks are necessary
for access, piping, ventilation, electrical cables, etc. arrangements are to be made
to maintain the watertight integrity.