Section 12(9)(a) in The Merchant Shipping (Cargo Ship Construction And Survey) Rules, 1974
(a)the skylights to spaces containing main propulsion machinery or oil fired boilers or auxiliary internal combustion type machinery of a total horse power of 1000 or over shall be capable of being closed and, where, practicable, opened, from outside the spaces in the event of fire and where they contain glass panels, such panels shall be of fire resisting construction fitted with wire reinforced glass and shall have external permanently attached shutters of steel or other equivalent material;