【余紹安】評論
Rule 34Manoeuvring and warning signals(a). When vessels are in sight of one another, a power-driven vessel underway, when manoeuvring as authorized orrequired 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”.