Rule 34 : Manoeuvring and warning signalsa. When vessels are in sight of one another, a power-driven vessel underway, when manoeuvring as authorized or required by these Rules, shall indicate that manoeuvre by the following signals on her whistle:one short blast to mean “I am altering my course to starboard”;two short blasts to mean “I am altering my course to port”;three short blasts to mean “I am operating astern propulsion”.b. Any vessel may supplement the whistle signals prescribed in paragraph (a) of this Rule by light signals, repeated as appropriate, whilst the … [Read more...]