Sound signals 2

A vessel at anchor may in addition to the bell and/or gong, sound one short, one prolonged and one short blast to give warning of her position, and of the possibility of collision, to an approaching vessel.
A vessel aground must ring the bell, and if required, sound the gong, and in addition, must ring three separate and distinct strokes on the bell immediately before and after the rapid ringing of the bell.
A vessel of less than 12 meters in length is not obliged to give the
previously described signals, but if she does not, shall make some other efficient sound signal at intervals of not more than 2 minutes.
A pilot vessel when engaged on pilotage duty shall, in addition to the
signals prescribed for power-driven vessels, sound an identity signal consisting of four short blasts.