Section 10(a) in The Merchant Shipping (Prevention of Collisions at Sea) Regulations, 1975
(a)The vertical sectors of electric lights, with the exception of lights on sailing vessels shall ensure that;(i)at least the required minimum intensity is maintained at all angles from 5 degrees above to 5 degrees below the horizontal.(ii)at least 60 per cent of the required minimum intensity is maintained from 7.5 degrees above to 7.5. degrees below the horizontal.
