Section 10 in The Merchant Shipping (Prevention of Collisions at Sea) Regulations, 1975
10. Vertical Sectors.
(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.(b)In the case of sailing vessels the vertical sectors of electric lights 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 50 per cent of the required minimum intensity is maintained from 25 degrees above to 25 degrees below the horizontal.(c)In the case of lights other than electric these specifications shall be met as closely as possible.
