This document discusses watertight integrity and weather tightness on ships. It covers requirements for openings in watertight bulkheads, doors to maintain watertight integrity, access doors and hatches, watertight doors or ramps to internally subdivide cargo spaces, and other closing appliances to ensure watertight integrity. Specific topics covered include requirements for sliding watertight doors, indicators to show if doors are open or closed, reinforcement around openings in bulkheads, and testing of watertight doors.

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Function 4:
Controlling the operation of
the ship and care for
persons onboard at the
management level.
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Watertight Integrity and
Weather tight

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1. The number of openings in watertight subdivisions is to
be kept to a minimum compatible with the design and
proper working of the ship. 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. The Administration may permit relaxation in
the watertightness of openings above the freeboard deck,
provided that it is demonstrated that any progressive
flooding can be easily controlled and that the safety of
the ship is not impaired.
Watertight Integrity
Part B-1 of SOLAS Chapter II-1 Regulation 25-9
Opening in watertight bulkheads and internal decks in cargo ships

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2. Doors provided to ensure the watertight integrity of
internal openings which are used while at sea are to be
sliding watertight doors capable of being remotely closed
from the bridge and are also to be operable locally from
each side of the bulkhead. Indicators are to be provided
at the control position showing whether the doors are
open or closed, and an audible alarm is to be provided at
the door closure. The power, control and indicators are to
be operable in the event of main power failure. Particular
attention is to be paid to minimizing the effect of control
system failure. Each power-operated sliding watertight
door shall be provided with an individual hand-operated
mechanism. It shall be possible to open and close the
door by hand at the door itself from both sides.

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3. Access doors and access hatch covers normally closed
at sea, intended to ensure the watertight integrity of
internal openings, shall be provided with means of
indication locally and on the bridge showing whether
these doors or hatch covers are open or closed. A
notice is to be affixed to each such door or hatch cover
to the effect that it is not to be left open. The use of
such doors and hatch covers shall be authorized by the
officer of the watch.

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4. Watertight doors or ramps of satisfactory construction
may be fitted to internally subdivide large cargo spaces,
provided that the Administration is satisfied that such
doors or ramps are essential. These doors or ramps may
be hinged, rolling or sliding doors or ramps, but shall not
be remotely controlled*. Such doors or ramps shall be
closed before the voyage commences and shall be kept
closed during navigation; the time of opening such doors
or ramps in port and of closing them before the ship
leaves port shall be entered in the logbook. Should any of
the doors or ramps be accessible during the voyage, they
shall be fitted with a device which prevents unauthorized
opening.

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5. Other closing appliances which are kept permanently
closed at sea to ensure the watertight integrity of internal
openings shall be provided with a notice which is to be
affixed to each closing appliance to the effect that it is to
be kept closed. Manholes fitted with closely bolted covers
need not be so marked.

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*refer MSC/Circ.651
MSC/Circular.651 - International Convention for the
Safety of Life at Sea, 1974, as amended - (adopted on 8
June 1994) - The Maritime Safety Committee
The need for the provision of position indicators to certain
doors which lead to main cargo spaces - (regulation 25-9,
paragraph 4)
. Those hinged, rolling and sliding watertight doors and
ramps which are fitted to subdivide large cargo spaces,
and are not required to be remotely controlled but are to
be secured closed whilst the ship is at sea and are
recorded as such in the ship’s log, should not be required
to be fitted with a position indicator display at the bridge
control position.

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In order to maintain the efficiency of a watertight
bulkhead it is desirable that it remains intact. However in
some instances it becomes necessary to provide access
between compartments on either side of a watertight
bulkhead and watertight doors are fitted for this purpose.
A particular example of this cargo ships is the direct
means of access required between the engine room and
the shaft tunnel. In passenger ships watertight doors are
more frequently found where they allow passengers to
pass between one point of the accommodation and
another.
Where a doorway is cut in the lower part of a watertight
bulkhead care must be taken to maintain the strength of
the bulkhead. The opening is to be framed and
Watertight Doors

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The opening is to be framed and reinforced, if the
vertical stiffeners are cut in way of the opening. If the
stiffener spacing is increased to accommodate the
opening, the scantlings of the stiffeners on either side of
the opening are increased to give an equivalent strength
to that of an unpierced bulkhead. The actual opening is
kept as small as possible, the access to the shaft tunnel
being about 1000 to 1250 mm high and about 700 mm
wide. In passenger accommodation the openings would
be somewhat larger.
Watertight doors shall be power-operated sliding doors
complying with the requirements capable of being closed
simultaneously from the central operating console at the
navigation bridge in not more than 60 s with the ship in
the upright position.

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The means of operation whether by power or by hand of
any power-operated sliding watertight door shall be
capable of closing the door with the ship listed to 15º
either way. Consideration shall also be given to the forces
which may act on either side of the door as may be
experienced when water is flowing through the opening
applying a static head equivalent to a water height of at
least 1 m above the sill on the centreline of the door.
Mild steel or cast steel watertight doors fitted below the
water line are either of the vertical or horizontal sliding
type. A swinging hinged type of door could prove
impossible to close in the event of flooding and is not
permitted. The sliding door must be capable of operation
when the ship is listed 15º, and be opened or closed from
the vicinity of the door as well as from a position above
the bulkhead deck.

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At this remote control position an indicator must be
provided to show whether the door is open or closed.
Vertical sliding doors may be closed by a vertical screw
thread which is turned by a shaft extending above the
bulkhead and fitted with a crank handle. This screw
thread turns in a gunmetal nut attached to the top of the
door, and a crank handle is also provided at the door to
allow it to be closed from this position. Often horizontal
sliding doors are fitted, and these may have a vertical
shaft extending above the bulkhead deck, which may be
operated by hand from above the deck or at the door.
This can also be power driven by an electric motor and
worn gear, the vertical shaft working through bevel
wheels, and horizontal screwed shafts turning in bronze
nuts on the door.

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The horizontal sliding door may also be opened and
closed by a hydraulic ram with a hydraulic hand pump
and with control at the door and above the bulkhead deck
with the larger number of watertight doors fitted in
passenger ships the doors may be closed by means of
hydraulic power actuated by remote control from a
central position above the bulkhead deck.
When in place all watertight doors are given a hose test,
but those in a passenger ship are required to be tested
under a head of water extending to the bulkhead deck.
This may be done before the door is fitted in the ship.
In approved positions in the upper tween decks well
above the waterline, hinged watertight doors are
permitted. These may be similar to the weathertight
doors fitted in superstructures, but are to have gunmetal
pins in the hinges.