In wartime and peacetime, communications are
necessary between U.S. Navy ships and merchantmen
sailing throughout the world. Vessels of many nations
come in contact with one another, exchanging
messages of varying degrees of importance.
This chapter discusses some of the facets of
international signaling, such as the manner of calling
and answering, message construction, and use of
procedure signals and signs. International signaling
procedures are in many respects similar to those used
by allied naval units. Every signalman must be aware,
however, there are significant differences.
When communicating with a merchantman, you
must remember to use international procedure.
Merchantmen do not have access to all of our
publications, nor are they required to know Navy
procedure. So take a little extra time and learn how to
communicate with merchantmen.
Much of the information you will need to know to
communicate with merchantmen is contained in the
International Code of Signals, Pub 102.
LEARNING OBJECTIVES: Explain the
procedure for signaling from the International
Code of Signals, using explanation and general
remarks, definitions, and general instructions.
Explain the procedures for signaling using
flags, flashing lights, sounds, radiotelephones,
and hand flags or arms to communicate with
The purpose of the International Code of Signals
is to provide ways and means of communication in
situations related essentially to safety of navigation
and persons, especially when language difficulties
arise. In the preparation of the Code, account was
taken of the fact that wide application of
radiotelephony and radiotelegraphy can provide
simple and effective means of communication in plain
language whenever language difficulties do not exist.
The Code consists of four chapters, an appendix, and
Chapter lSignaling Instructions
Chapter 2General Signal Code
Chapter 3Medical Signal Code
Chapter 4Distress and Lifesaving Signals and
AppendixU.S/Russia Supplementary Signals
for Naval Vessels
IndexesSignaling Instructions and General
Signal Code, and Medical Signal Code
When a man-of-war and a merchant ship desire to
communicate, it is extremely important for those
involved in the use of the Code to follow the
prescribed terminology. The following terms have the
1. Sound signaling: Any method passing Morse
signals by means of siren, whistle, foghorn, bell, or
other sound apparatus.
2. Identity Signal: The group of letters and figures
assigned to each station by its administration.
3. Station: A ship, aircraft, survival craft, or any
place at which communications can be effected by any
4. Station of origin: Station where the originator
submits a signal for transmission, regardless of the
method of communication used.
5. Station of destination: Station in which the
signal is finally received by the addressee.
6. Receiving station: The station by which a signal
is actually being read.
7. At the dip: A hoist or signal is said to be at the
dip when it is about half of the full extent of the halyards.
8. Group: Denotes more than one continuous letter
and/or numeral that together compose a signal.