11.1 A ventilator shall be of efficient construction
and be provided with a permanently attached means of weathertight
closure.
11.2 A ventilator shall be kept as far inboard
as practicable and the height above the deck of the ventilator opening
shall be sufficient to prevent the admission of water when the vessel
is heeled.
11.3 The Administration may permit the fitting
of 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, provided
that it is demonstrated with reference II/11.2 that downflooding
will not occur via the ventilator in any foreseeable situation.