25.2.3.1 Doorways in superstructures, deckhouses
and exposed machinery casings situated on the weather deck and which
enclose accesses to spaces below deck should be provided with efficient
weathertight doors. Weathertight doors should be secured in the closed
position when the vessel is towing and the doors should be marked
clearly to this effect.
25.2.3.2 Machinery air intakes and machinery space
ventilators which must be kept open during towing operations should
be served by means of high coaming ventilators as protection from
downflooding.
25.2.3.3 Generally, airpipes and ventilators should
be kept as far inboard as possible and be fitted with automatic means
of closure when downflooding to the compartments served would endanger
the safety of the vessel.