Section 30(3) in The Merchant Shipping (Prevention of Pollution by Oil from Ships) Rules, 2010
(3)In oil tankers of one hundred and fifty gross tonnage and above delivered after 31st December, 1979, as defined in sub-rule (45) of rule 1A. means shall be provided for stopping the discharge into the sea of ballast water or oil-contaminated water from cargo tank areas, other than those discharges below the waterline permitted under sub-rule (6), from a position on the upper deck or above located so that the manifold in use referred to in sub-rule (1) and the discharge to the sea from the pipelines referred to in sub-rule (2) may be visually observed:Provided that means for stopping the discharge need not be provided at the observation position if a positive communication system such as a telephone or radio system is provided between the observation position and the discharge control position.
