Competence 8: Transmit and receive information by visual signalling KUP 31: Ability to use the International Code of Signals

KUP 31: Ability to use the International Code of Signals

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Learning objective:

The learning objective of this lesson is to develop the ability to use the signals of the International Code of Signals (INTERCO), including flag signaling, flashing light and sound signaling, voice over a loud hailer, radiotelegraphy and radiotelephony.

Learning Content:

1. Flag signaling

A set of signal flags consists of twenty-six alphabetical flags, ten numeral pennants, three substitutes, and the answering pennant ¹.

How wo call

The identity signal of the station(s) addressed is to be hoisted with the signal. If no identity signal is hoisted it will be understood that the signal is addressed to all stations within visual signaling distance. If it is not possible to determine the identity signal of the station to which it is desired to signal, the group “VF” = “You should hoist your identity signal” or “CS” = “What is the name or identity signal of your vessel (or station)?” should be hoisted first; at the same time the station will hoist its own identity signal. The group “YQ” = “I wish to communicate by . . . with vessel bearing . . . from me” can also be used.

How to answer signals

All stations to which signals are addressed or which are indicated in signals are to hoist the answering pennant at the dip as soon as they see each hoist and close up immediately, when they understand it; it is to be lowered to the dip as soon as the hoist is hauled down at the transmitting station, being hoisted close up again as soon as the next hoist is understood.

How to complete a signal

The transmitting station is to hoist the answering pennant singly after the last hoist of the signal to indicate that the signal is completed. The receiving station is to answer this in a similar manner to all other hoists.

How to act when signals are not understood

If the receiving station cannot clearly distinguish the signal made to it, it is to keep the answering pennant at the dip. If it can distinguish the signal but cannot understand the meaning of it, it can hoist the following signals: “ZQ” = “Your signal appears incorrectly coded. You should check and repeat the whole”, or “ZL” = “Your signal has been received but not understood”.

2. Flashing light and sound signaling

The Morse symbols representing letters, numerals, etc., are expressed by dots and dashes which are signaled either singly or in combination. The dots and dashes and spaces between them should be made to bear the following ratio, one to another, as regards their duration ¹:
(a) A dot is taken as the unit;
(b) A dash is equivalent to three units;
(c) The space of time between any two elements of a symbol is equivalent to one unit; between two complete symbols it is equivalent to three units; and between two words or groups it is equivalent to seven units.

In flashing light and sound signaling, it is best to err on the side of making the dots rather shorter in their proportion to the dashes as it then makes the distinction between the elements plainer. The standard rate of signaling by flashing light is to be regarded as forty letters per minute. Detailed instructions for signaling by flashing light and sound are given in Chapter 1, Sections 6 and 7, Pages 10 through 12 in International Code of Signals.

3. Voice over a loud hailer

Whenever possible plain language should be used but where a language difficulty exists groups from the International Code of Signals could be transmitted using the phonetic spelling tables ¹.

4. Radiotelegraphy and radiotelephony

When radiotelegraphy or radiotelephony is used for the transmission of signals, operators should comply with the Radio Regulations of the International Telecommunication Union then in force. Details refer to Chapter 1, Section 8 of International Code of signals ¹.

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