5.1 General
5.1.1 A vessel should be designed and constructed in a manner which will prevent the
ingress of sea water and in particular comply with the following requirements. For
strength and watertightness of closing appliances only, the requirements of ISO 12216
are considered acceptable. See Appendix 13.
5.2 Hatchways and Hatches
5.2.1 General Requirements
5.2.1.1 A hatchway which gives access to spaces below the weather deck should be of
efficient construction and be provided with efficient means of weathertight closure. For
cargo hatchways, reference should be made to section 25.3.
5.2.1.2 A cover to a hatchway should be hinged, sliding, or permanently secured by other
equivalent means to the structure of the vessel and be provided with sufficient locking
devices to enable it to be positively secured in the closed position.
5.2.1.3 A hatchway with a hinged cover which is located in the forward half of the
vessel should have the hinges fitted to the forward side of the hatch, as protection of
the opening from boarding seas, except where it is not possible to do so, due to the
shape of the hatch or the moulding it is in. A hatch with the hinges on the after side
of the hatch should be secured closed at sea, and be provided with a suitable blank.
This is not intended to apply to small technical spaces drained directly overboard, e.g.
anchor lockers.
5.2.1.4 Hatches which are used for escape purposes should be capable of being opened
from both sides.
5.2.1.5 Hatches in recessed or stepped decks of vessels described in 4.3.1.2, that
provide access to sea inlet valves, should have access openings at least 300 millimetres
(mm) above the minimum freeboard to deck (see 12.2.2), or the sea inlet valves fitted
with remote closing devices.
5.2.2 Hatchways which are Open at Sea
In general, hatches should be kept secured closed at sea. However, a hatch which is to
be open at sea for lengthy periods should be:
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.1 kept as small as practicable, but never more than 1 square metre (m˛) in plane
area at the top of the coaming;
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.2 located on the centre line of the vessel or as close thereto as practicable;
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.3 fitted such that the access opening is at least 300mm above the top of the
adjacent weather deck at side.
5.3 Doorways and Companionways
5.3.1 Doorways Located Above the Weather Deck
5.3.1.1 A doorway located above the weather deck which gives access to spaces below
should be provided with a weathertight door. The door should be of efficient
construction, permanently attached to the bulkhead, not open inwards, and sized such
that the door overlaps the clear opening on all sides, and has efficient means of
closure which can be operated from either side.
5.3.1.2 A doorway should be located as close as practicable to the centre line of the
vessel. However, if hinged and located in the side of a house, the door should be hinged
on the forward edge.
5.3.1.3 A doorway which is either forward or side facing should be provided with a
coaming, the top of which is at least 300mm above the weather deck. A coaming may be
portable provided it can be permanently secured to the structure of the vessel and can
be locked in position whilst at sea.
5.3.2 Companion Hatch Openings
5.3.2.1 A companion hatch opening from a cockpit or recess which gives access to spaces
below the weather deck should be fitted with a coaming or washboard, the top of which is
at least 300mm above the sole of the cockpit or recess.
5.3.2.2 When washboards are used to close a vertical opening they should be so arranged
and fitted that they will not become dislodged.
5.3.2.3 The maximum breadth of the opening of a companion hatch should not exceed 1
metre.
5.4 Skylights
5.4.1 A skylight should be of efficient weathertight construction and should be located
on the centre line of the vessel, or as near thereto as practicable, unless it is
required to provide a means of escape from a compartment below deck.
5.4.2 When a skylight is an opening type it should be provided with efficient means
whereby it can be secured in the closed position.
5.4.3 A skylight which is provided as a means of escape should be capable of being
opened from both sides.
5.4.4 Unless the glazing material and its method of fixing in the frame is equivalent in
strength to that required for the structure in which it is fitted, a portable “blank”
should be provided which can be efficiently secured in place in event of breakage of the
glazing. The blank should be of suitable material and strength to the satisfaction of
the Certifying Authority.
5.5 Portlights and Windows
5.5.1 A portlight or window to a space below the weather deck or in a step, recess,
raised deck structure, deckhouse or superstructure protecting openings leading below the
weather deck should be of efficient construction which provides weathertight integrity
(and be of strength compatible with size) for the intended area of operation of the
vessel.
5.5.2 A portlight or window should not be fitted in the main hull below the weather
deck, unless the glazing material and its method of fixing in the frame are equivalent
in strength, with regard to design pressure, to that required for the structure in which
it is fitted.
5.5.3 An opening portlight should not be provided to a space situated below the weather
deck.
5.5.4 Portlights, windows and their frames should meet the appropriate Marine Standards
defined in equivalent British, European, National or International Standards or
standards of a recognised Classification Society (see MSN 1672(M+F)(Amendment 3), as
amended).
5.5.5 A portlight fitted below the weather deck and not provided with an
attached deadlight should be provided with a "blank" (the number of blanks should be
sufficient for at least half of the number of such portlights of each different size in
the vessel), which can be efficiently secured in place in the event of breakage of the
portlight. The blank should be of suitable material and strength to the satisfaction of
the Certifying Authority. Such a "blank" is not required for a non-opening portlight
which satisfies section 5.5.2.
5.5.6 An opening portlight should not exceed 250mm in diameter or equivalent area.
5.5.7 A window fitted in the main hull below the weather deck should meet the
requirements of section 5.5.2, or be provided with a blank meeting the requirements of
section 5.5.8.
5.5.8 In a vessel which operates more than 60 miles from a safe haven, portable "blanks"
for windows should be provided (the number of blanks should be sufficient for at least
half of the number of such windows of each different size in the vessel) which can be
efficiently secured in place in the event of breakage of a window.
5.5.9 For the wheelhouse:
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.1 windows and their frames should meet the requirements of section 5.5.4, having
due regard to the increased thickness of windows comprising one or more
laminations in order to achieve equivalent strength; and
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.2 polarised or tinted glass should not be used in windows provided for
navigational visibility (although portable tinted screens may be provided for
nominated windows).
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.3 wheelhouse visibility – see sect 9.1.2 and 19.6
5.6 Ventilators and Exhausts
5.6.1 A ventilator should be of efficient construction and, where situated on the
weather deck and not complying with section 5.6.3, should be provided with a readily
available means of weathertight closure, consideration should be given to requirements
of Fire Protection (section 14).
5.6.2 A ventilator should be kept as far inboard as practicable and the height above the
deck of the ventilator opening should be sufficient to prevent the ready admission of
water when the vessel is heeled (see sections 11.3, 11.4, 11.6 and 11.8).
5.6.3 A ventilator which must be kept open, e.g. for the supply of air to machinery or
for the discharge of noxious or flammable gases, should be specially considered with
respect to its location and height above deck having regard to section 5.6.2 and the
downflooding angle (see sections 11.3, 11.4, 11.6 and 11.7).
5.6.4 Vessels which are fitted with engine air intakes in the hull side, which do not
satisfy the requirements of 5.6.1, 5.6.2 and 5.6.3, may be accepted by a Certifying
Authority, but the risk of fire in the machinery space or downflooding should be taken
into consideration and restrictions on operations will be necessary.
Such an air intake must be capable of being remotely closed before the activation of a
fixed fire extinguishing system for the machinery space, as required by 15.6.3.
5.6.5 An engine exhaust outlet which penetrates the hull below the weather deck should
be provided with means to prevent backflooding into the hull through the exhaust system.
The means may be provided by system design and/or arrangement, built-in valve or a
portable fitting which can be applied readily in an emergency.
5.7 Air Pipes
5.7.1 When located on the weather deck, an air pipe should be kept as far inboard as
possible and have a height above deck sufficient to prevent inadvertent downflooding
when the vessel is heeled (see sections 11.3, 11.4, 11.6 and 11.7).
5.7.2 An air pipe, of greater than 10mm inside diameter, serving a fuel or other tank
should be provided with a permanently attached means of weathertight closure. Means of
closure may be omitted if it can be shown that the open end of the air pipe is afforded
adequate protection by other means, which will prevent the ingress of water.
5.7.3 An air pipe serving a fuel tank (also see section 7.4.) or other tank, where
provided with a closing appliance, should be of a type which will prevent excessive
pressure on the tank boundaries. Provision should be made for relieving a vacuum when
tanks are being drawn from or emptied.
5.8 Sea Inlets and Discharges
5.8.1 An opening below the weather deck should be provided with a positive means of
closure. The number of inlets and discharges should be kept to an operational minimum.
5.8.2 When an opening is for the purpose of an inlet or discharge below the waterline it
should be fitted with a seacock, valve or other effective means of closure which is
either remotely operated or readily accessible in an emergency. Discharge lines should
also have an automatic non-return valve.
5.8.3 When an opening is for a log or other sensor, which is capable of being withdrawn,
it should be fitted in an efficient watertight manner and provided with an effective
means of closure when such a fitting is removed. A non-metallic, or non-flush metallic
fitting, log or sensor should not be fitted in machinery spaces or in any spaces in
vessels that operate at high speed unless located in small cofferdams designed for the
purpose and with any access panels and service transits made watertight. If access is
designed to be opened at sea, a test cock should be provided.
5.8.4 Inlet and discharge pipes from marine toilets should be provided with shell
fittings as required by section 5.8.2. When the rim of a marine toilet is less than
300mm above the deepest waterline of the vessel, unless otherwise indicated by
manufacturer’s recommendations, anti - syphon measures should be provided.
5.8.5 Observation glasses fitted in sea water systems below the deepest anticipated
waterline, including any trim or heel, shall be so protected as to minimise the risk of
mechanical damage, failure and consequential flooding.
5.9 Materials for Valves and Associated Piping
5.9.1 A valve or similar fitting attached to the side of the vessel below the waterline,
within a machinery space or other high fire risk area, and essential system piping
should be normally of steel, bronze, copper, or other non-brittle fire resistant
material or equivalent.
5.9.2 When plasticfootnote piping or flexiblefootnote pipe is used it should not contribute any additional risks
or spread of fire, be of good quality and of a type suitable for the intended purpose.
Plastic / non-metallic piping should only be allowed where consideration has been given
to the usage of the pipe, e.g. with respect to system type (open or closed loop), system
pressure, system temperature, system pipe internal fluid, location etc., using class
requirements and IMO A.753(18) as amended for guidance. Plastic pipes should not be used for cargo
pipes carrying flammable liquids, described in 7.9.
5.9.3 Materials readily rendered ineffective by heat must not be used for fire main,
hydrants, valves or cocks. Materials with a melting point above 1000 °C may normally be
accepted as meeting the above. Fittings which incorporate low melting point components
may be accepted, provided they have passed a fire test in accordance with ISO 10497. It
should be taken into account in the test that it cannot be guaranteed that the fire main
will be flooded at all times.
5.9.4 Any Flexible or non-metallic piping, and engine room bulkhead and deck
penetrations, where failure would present a risk of flooding, which contribute any
additional risk of spread of fire, fitted in a machinery space or fire risk area should
be of fire resistant material in accordance with ISO Standard 15540 or IMO A.753(18)footnote as amended, and the pipes are used in accordance with the
fire endurance requirements matrix in Appendix 4 of the Res A.753(18), or exhaust quality rubber hosing for exhaust systems where
applicable (see Appendix 13), and a means should be provided to stop the ingress of
water in the event of the pipe being damaged, operable from outside the space. (See
section 5.9.1 for valve requirements).
5.9.5 Where a vessel is a multihull (i.e. comes under section 7.1.5 or a
complex workboat described in 14.10.1), and where bilge pumping and fire main are
provided in excess of the code requirements this may be taken into consideration by the
Certifying Authority in any risk assessment of the suitability of use of non-metallic
pipes in these systems, subject to 5.9.2 above.