Section 35 in Prevention Of Collision On National Waterways Regulations, 2002
35. Sound signals in restricted visibility.-
In or near an area of restricted visibility, where by day or night, signals prescribed in this regulation shall be used as follows:(a)A mechanically propelled vessel making way through the water shall sound at intervals of not more than 2 minutes one prolonged blast.(b)A mechanically propelled vessel underway but stopped and making no way through the water shall sound at intervals of not more than 2 minutes. Two prolonged blasts in succession with an interval of about 2 seconds between them.(c)A vessel not under command, a vessel restricted in her ability to manoeuvre, a vessel constrained by her draught, vessel engaged in towing, fishing or pushing another vessel , shall at intervals of not more than 2 minutes three blasts in succession namely one prolonged followed by two short blasts.(d)A vessel at anchor shall at intervals of not more than one minute ring the bell rapidly for about 5 seconds. A vessel at anchor may in addition sound three blasts in succession namely one short one prolonged and one short blast to give warning on her position, and possibility of collision to any approaching vessel. A vessel aground shall give three separate and distinct strokes on the bell immediately before and after the rapid ringing of the bell.(e)A vessel of less than 10 metres in length shall not be obliged to give the abovementioned signals but shall make some other effective sound signal at intervals of not more than 2 minutes.
