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—INTERNATIONAL—

Sound and Light Signals

RULE 34

Maneuvering and Warning Signals

(a) When vessels are in sight of one another, a power-driven ves-

sel underway, when maneuvering as authorized or required by these
Rules, shall indicate that maneuver 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,
while the maneuver 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.