According to the International Convention on Load Lines, 1966, ventilators in position 1 shall have coamings of a height of at least 900 milimetres above the deck; in position 2 the coamings shall be of a height at least 760 milimetres above the deck. In both cases, ventilators shall be provided with efficient weathertight closing appliances. Ventilators in position 1the coamings of which extend to more than 4.5 metres above the deck, and in position 2, the coamings of which extend to more than 2.3 metres above the deck, need not be fitted with closing arrangements.
Note: Ventilator openings for the machinery space shall be fitted in a position where weathertight closing appliances are not required.