(1)Single vessel when vessels are in-sight of one another a mechanically propelled vessel underway, when maneuvering as authorized or required by these regulations, shall indicate her intentions by the following signals on her whistle.(a)One short blast (a blast of about 1 second duration) to indicate."I am altering my course to starboard"(b)Two short blasts to indicate " I am altering course to port"(c)Three short blasts to indicate "I am operating stern propulsion."
