6.8.1
footnote
Where bulwarks
on the weather portion of freeboard or superstructure deck or, in
fishing vessels, the working deck form wells, freeing ports should
be arranged along the length of the bulwark as to ensure that the
deck is freed of water most rapidly and effectively. Lower edges of
freeing ports should be as near the deck as practicable.
6.8.2
footnote
In ships to which
the International Convention on Load Lines, 1966, applies freeing
ports should comply with regulation 24 of
this Convention, which is as follows:
-
.1 Except as provided in subparagraphs .2 and
.3, the minimum freeing port area (A) on each side of the ship for
each well on the freeboard deck should be that given by the following
formulae in cases where the sheer in way of the well is standard or
greater than standard. The minimum area for each well on superstructure
decks should be one-half of the area given by the formulae.
Where the length of bulwark (l) in the well is
20 m or less,
A = 0.7 + 0.035l square metres;
where l exceeds 20 metres,
A = 0.07 l square metres;
(in no case l should be taken greater than 0.7
L).
If the bulwark is more than 1.2 m in average height the required
area should be increased by 0.004 square metres per metre of length
of well for each 0.1 m difference in height. If the bulwark is less
than 0.9 m in average height, the required area may be decreased by
0.004 square metres per metre of length of well for each 0.1 m difference
in height.
-
.2 In ships with no sheer the calculated area
should be increased by 5%. Where the sheer is less than the standard,
the percentage should be obtained by interpolation.
-
.3 Where a ship is fitted with a trunk which does
not comply with the requirements of regulation
36(1)(e) of the International Convention on Load Lines, 1966,
or where continuous or substantially continuous hatchway side coamings
are fitted between detached superstructures the minimum area of the
freeing port openings should be calculated from the following table:
| Breadth of hatchway or trunk in relation to breadth of the
ship
|
Area
of freeing ports in relation to the total area of the bulwarks
|
| 40%
or less
|
20%
|
| 75%
or more
|
10%
|
The area of freeing ports at intermediate breadths
should be obtained by linear interpolation.
-
.4 In ships having superstructures which are open
at either or both ends, adequate provision for freeing the space within
such superstructures should be provided to the satisfaction of the
Administration.
-
.5 Two thirds of the freeing port area required
should be provided in the half of the well nearest the lowest point
of the sheer curve.
-
.6 All such openings in the bulwarks should be
protected by rails or bars spaced approximately 230 mm apart. If shutters
are fitted to freeing ports, ample clearance should be provided to
prevent jamming. Hinges should have pins or bearings of non-corrodible
material. If shutters are fitted with securing appliances, these appliances
should be of approved construction.
6.8.3
footnote
In decked fishing
vessels of 12 m in length and over, freeing ports should comply with
the following:
-
.1 The minimum freeing port area (A) in square
metres, on each side of the vessel for each well on the working deck
should be determined in relation to the length (l) and
height of bulwark in the well as follows:
-
.1.1 A = K × l
where:
K = 0.07 for vessels of 24 m in length and over;
K = 0.035 for vessels of 12 m in length;
for intermediate lengths the value of K should be obtained by
linear interpolation (l need not be taken as greater
than 70% of the vessel's length).
-
.1.2 Where the bulwark is more than 1.2 m in average
height the required area should be increased by 0.004 square metres
per metre of length of well for each 0.1 m difference in height.
-
.1.3 Where the bulwark is less than 0.9 m in average
height, the required area may be decreased by 0.004 square metres
per metre of length of well for each 0.1 m difference in height.
-
.2 The freeing port area calculated according
to .1 should be increased where the Administration or competent authority
considers that the vessel's sheer is not sufficient to ensure rapid
and effective freeing of the deck of water.
-
.3 Subject to approval of the Administration or
competent authority, the minimum freeing port area for each well on
the superstructure deck should be not less than one-half the area
(A) given in .1 except that where the superstructure deck forms a
working deck for fishing operations the minimum area each side should
be not less than 75% of the area (A).
-
.4 Freeing ports should be so arranged along the
length of bulwarks as to provide the most rapid and effective freeing
of the deck from water. Lower edges of freeing ports should be as
near the deck as practicable.
-
.5 Poundboards and means for stowage and working
the fishing gear should be arranged so that the effectiveness of the
freeing ports will not be impaired or water trapped on deck and prevented
from easily reaching the freeing ports. Poundboards should be so constructed
that they can be locked in position when in use and will not hamper
the discharge of shipped water.
-
.6 Freeing ports over 0.3 m in depth should be
fitted with bars spaced not more than 0.23 m nor less than 0.15 m
apart or provided with other suitable protective arrangements. Freeing
port covers, if fitted, should be of approved construction. If devices
are considered necessary for locking freeing port covers during fishing
operations they should be to the satisfaction of the competent authority
and easily operable from a readily accessible position.
-
.7 In vessels intended to operate in areas subject
to icing, covers and protective arrangements for freeing ports should
be capable of being easily removed to restrict ice accumulation. Size
of opening and means provided for removal of these protective arrangements
should be to the satisfaction of the competent authority.
-
.8 In addition, in fishing vessels of 12 m in
length and above but less than 24 m in length where wells or cockpits
are fitted in the working deck or superstructure deck with their bottoms
above the deepest operating waterline, efficient non-return means
of drainage overboard should be provided. Where bottoms of such wells
or cockpits are below the deepest operating waterline, drainage to
the bilges should be provided.
6.8.4 In offshore supply vessels the Administration
should give special attention to adequate drainage of pipe stowage
positions, having regard to the individual characteristics of the
vessel. However, the area provided for drainage of the pipe stowage
positions should be in excess of the required freeing port area in
the cargo deck bulwark and should not be fitted with shutters.