5.4.1 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.
5.4.2 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.
5.4.3 Portlights fitted in the hull of the vessel
below the level of the weather deck should be either non-opening or
of a non-readily opening type, have a glazed diameter of not more
than 250mm, or equivalent area, and be in accordance with a standard
recognised by the Administration. Portlights of the non-readily opening
type must be secured closed when the vessel is in navigation. Proposals
to accept portlights, to a recognised standard, greater than 250mm
diameter, up to a maximum of 400mm or equivalent area, maybe considered,
with due regard to their fore and aft, and vertical positioning, to
the satisfaction of the Certifying Authority. Proposals for larger
portlights may be considered by the Administration.
5.4.4 Portlights, windows and their frames should
meet the appropriate Marine Standards defined in equivalent British,
European, National or International Standards or Classification Rules.
5.4.5 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 5.4.2.
5.4.6 A window fitted in the main hull below the
weather deck should meet the requirements of Section 5.4.2, or be
provided with a blank meeting the requirements of Section 5.4.7.
5.4.7 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.
Such a "blank" is not required for a window which satisfies
Section 5.4.2.
5.4.8
For the wheelhouse:-
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.1 windows and their frames should meet the requirements
of Section 5.4.4, having due regard to the increased thickness of
windows comprising one or more laminations in order to achieve equivalent
strength;
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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); and