(a) 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 manoeuvre is being carried out:
-
(i) these light signals shall have the following
significance:
- one flash to mean “I am altering my course to starboard”;
- two flashes to mean “I am altering my course to port”;
- three flashes to mean “I am operating astern propulsion”;
-
(ii) the duration of each flash shall be about
one second, the interval between flashes shall be about one second,
and the interval between successive signals shall be not less than
ten seconds;
-
(iii) the light used for this signal shall, if
fitted, be an all-round white light, visible at a minimum range of
5 miles, and shall comply with the provisions of Annex I to these Regulations.
(c) When in sight of one another in a narrow channel
or fairway:
-
(i) a vessel intending to overtake another shall
in compliance with Rule 9(e)(i) indicate
her intention by the following signals on her whistle:
- two prolonged blasts followed by one short blast to mean “I
intend to overtake you on your starboard side”;
- two prolonged blasts followed by two short blasts to mean “I
intend to overtake you on your port side”.
-
(ii) the vessel about to be overtaken when acting
in accordance with Rule 9(e)(i) shall
indicate her agreement by the following signal on her whistle:
- one prolonged, one short, one prolonged and one short blast, in
that order.
(d) When vessels in sight of one another are approaching
each other and from any cause either vessel fails to understand the
intentions or actions of the other, or is in doubt whether sufficient
action is being taken by the other to avoid collision, the vessel
in doubt shall immediately indicate such doubt by giving at least
five short and rapid blasts on the whistle. Such signal may be supplemented
by a light signal of at least five short and rapid flashes.
(e) A vessel nearing a bend or an area of a channel
or fairway where other vessels may be obscured by an intervening obstruction
shall sound one prolonged blast. Such signal shall be answered with
a prolonged blast by any approaching vessel that may be within hearing
around the bend or behind the intervening obstruction.
(f) If whistles are fitted on a vessel at a distance
apart of more than 100 metres, one whistle only shall be used for
giving manoeuvring and warning signals.