Section 34(a) in Prevention Of Collision On National Waterways Regulations, 2002
(a)Single vessel when vessels are in sight of one another a mechanically propelled vessel underway, when manoeuvring as authorised or required by these regulations, shall indicate her intentions by the following signals on her whistle(i)One short blast to mean "I am altering my course to starboard".(ii)Two short blasts to mean, "I am altering my course to port".(iii)Three short blast to mean "I am operating stern propulsion".
