signal or signals?
Answer. By IM (the signals sign).
Question. Of what does the office reference number and date
Answer. Of a four (or five) figure group, the first tw r o (or
three) figures of which designate an office or officer, the last two
the day of the month.
Question. What is the first group of the text?
Answer. The office reference number and date group is the
first group of the text and, when used, counts as one group in
counting the total number of groups or words.
Question. Is the office reference number and date group to be
Answer. They are not, unless they appear in the body of the
Question. What does the text comprise?
Answer. The communication itself, whether in plain language,
code, or groups from a signal book.
Question. Of what does the time of origin number consist?
INSTRUCTIONS FOE COAST GUARD STATIONS. 219
Answer. It consists of a four-figure group, the first two repre-
senting hours from midnight, the last two the minutes past the
Question. Is the time of origin number to be coded?
Answer. It is not, unless it appears in the body of the text.
Question. Where does the time of origin number appear in a
message and how is it counted?
Answer. It is the last group of the text and is counted as one
group in counting the total number of groups or words.
Question. What is the time of receipt number?
Answer. The time of receipt is a four-figure group, the first
two figures representing the hours past midnight, the last two
the minutes past the hour.
Question. What does the time of receipt indicate and of what
importance is it?
Answer. It indicates the time a dispatch was received; it is
of importance only in relayed dispatches and in locating delays
Question. When the number of words or groups is stated in
the prefix, does this number include the time of receipt sign or
time of receipt group?
Answer. It does not.
Question. How is the end of tr admission indicated?
Answer. By the "finale" signAR, or the "finish" sign VA.
Question. With what should dispatches ordinarily terminate?
Answer. With a " finale " sign AR, and not with a " finish "
Question. What does the " finish " sign mean and when is it
to be used?
Answer. It means " communication finished " and should be
used only when there is nothing more to follow.
Question. Give an example to illustrate the various parts of a
dispatch (flashing light).
Answer. The Wyoming (B 32) has a code dispatch : " 1721
ABCD EFGH 2013 " received from the Texas (B 35) to transmit
to the New York (B 34) addressed to or for further transmis-
sion to the New Mexico (B 40).
The proper position of the various procedure signs in a dis-
patch, when their use is required, is indicated in the right-hand
220 INSTRUCTIONS FOR COAST GUARD STATIONS.
Example of a dispatch.
Parts of the dispatch.
Position of prescribed
procedure signs when
their use is required.
New York receiving .
Preamble . ...
Pass follo'ving to
Procedure signs T
Z, and L.
Procedure sign V
Oifice reference No
Number of groups, 4. . .
Text is in code
Originated by Office
assigned number 17
on 21st day of cur-
Code group .
Procedure signs G, Y,
GR, and UN. __
Procedure signs BT,
II, and fST
Time of origin No
Dispatch written 8.13
GR 4 ...
T^' 4- 4 1
(Being in code )
II . .
Time of receipt
Time of receipt
Received on the New
End of dispatch
York at 8.42 p. m.
Procedure signs B, Q,
INSTRUCTIONS FOR COAST GUARD STATIONS. 221
Question. What system is to be used in answering or repeat-
ing a dispatch?
Answer. The unit replying to or repeating a dispatch shall
use the same system in which it is sent, unless it is clearly im- ^
practicable to do so.
Question. What conditions should govern the selection of the
system in sending dispatches?
Answer. The system selected will depend upon the importance
of the signal or dispatch, the number of units addressed, the
distance the signal or dispatch must be transmitted, and condi-
tions affecting visibility. The system selected should be the one
which would interfere least with other signaling, if there be
any, yet sufficient to insure attracting attention promptly.
Question. What means is employed to attract attention?
Answer. Any means of attracting attention may be used
which does not interfere with the purport of the signal or dis-
Question. Should it become necessary at any time to annul a
signal during its transmission, or even while the signal " execu-
tion " is being displayed, what is to be done?
Answer. It is merely necessary to send N (negative) as a
general signal, using a different system of transmission (or sec-
ond blinker tube), following the prescribed procedure.
Question. "In calling out the letters and signs for the recorder,
how is accuracy obtained?
Answer. They are to be called out by their names, as " Boy,"
not " B " ; " Roger," not " R " ; " Received sign," not " R."
Question. From whom are signals considered to emanate and
to whom to be addressed on board ship?
Answer. They are considered to emanate from the senior
officer of the unit of origin and to be addressed to the senior
officer of the unit to which they are addressed.
Question. What are the principal methods of transmitting
Answer. Flag hoist, flashing light, and radio.
Question. What secondary methods are available?
Answer. Semaphore, wigwag, sound, pyrotechnic, etc.
Question. In order to meet the requirements of each of the
three principal methods of transmitting signals, what equivalent
has each letter, numeral, and special sign?
222 INSTRUCTIONS FOR COAST GUARD STATIONS.
Answer. Each letter, numeral, and special sign has a name, a
flag or pennant equivalent, and a dot and dash equivalent.
Question. In transmitting signals by flashing; light (or by other
means employing the dot and dash characters), what is neces-
sary in order that the receiving unit may read a signal cor-
Answer. A decided pause should be made between repetitions
of signals in order to avoid running the repetitions together, and
thus causing the receiving unit to read a signal other than the
.Question. How would you illustrate this?
Answer. In sending the signal BCD, it should be sent BCD
(decided pause), BCD (decided pause), BCD (decided pause),
etc., and not BCDBCDBCD, etc., for in the latter case the receiv-
ing unit might possibly read the signal CDB or DBC (particu-
larly if the first letter or first two letters were missed), thus
reading a signal entirely different in meaning from the one
Question. What is the character of all dispatches transmitted
by visual methods considered to be and from whom are they
considered to emanate and to whom to be addressed?
Answer. Unless otherwise indicated they are considered to be
official and to emanate from the senior officer on board the ship
of origin and to be addressed to the senior officer on board the
Question. Is each dispatch required to have a specific address
Answer. No ; except that dispatches intended for the com-
manding officer of a ship, which is a flagship, shall be prefaced
" To shipsig," and dispatches from the commanding officer of a
ship which is a flagship shall be prefaced " From shipsig."
Question. How are unofficial dispatches prefaced?
Answer. By the letters UN followed immediately by the name
of the addressee and the name of the originator ; thus, " UN for
Captain Smith from Captain Jones." No unofficial dispatch
shall be sent unless signed by and addressed to an officer, except
by special permission in each case.
Question. How are dispatches identified?
Answer. By their " office reference number and date group "
and the " time of origin number."
INSTRUCTIONS FOR COAST GUARD STATIONS. 223
Question. In acknowledging a dispatch, how is it referred to?
Answer. By "office reference number and date group" (if
used) and "time of origin number," as Y 0327 II 1751.
Question. What is necessary in dispatches which it is desired
to have acknowledged?
Answer. They should contain the procedure sign Y in the'
Question. How often is any dispatch in code to be transmit-
Answer. It is to be sent twice, i. e., immediately upon com-
pletion of the first transmission the repeat sign, IMI, is to be
made, and the complete dispatch again transmitted. When the
letter C or the letter G- is used for the purpose of checking or
repeating back a code dispatch, the dispatch is to be transmitted
only once in such cases.
FLASHING-LIGHT METHODS OF TRANSMISSION.
Question. In systems using the flashing-light method of trans-
mission, what are used?
Answer. The International Morse alphabet and numerals and
special Morse signs are used.
Question. How are the characters made?
Answer. By alternately exposing and obscuring the light, a
short flash representing the " dot " and a long flash the " dash."
The characters should be made deliberately and distinctly.
Question. What ratio must the dots and dashes, and the
spaces between them, bear? *
Answer. A dot is taken as a unit.
A dash is equivalent to three units.
An acknowledging flash is equivalent to six units.
A space between two elements of a letter or sign is equal to
one unit. Thus, the letter D ( ) has three units for the
dash, one unit space, one unit " dot," one unit space, one unit
A space between two complete letters or signs is equal to a
dash, or three units.
A space between words, or groups, is equal to two dashes, or
Question. Should this ratio be carefully adhered to?
Answer. Yes ; whatever be the rate of transmission. In slow
transmission, with heavy searchlight apparatus or with sluggish
224 INSTRUCTIONS FOE COAST GUARD STATIONS.
lights, it is difficult to appreciate the relative length of dots and
dashes, and experience has shown it best to accentuate the dots
by making them shorter in proportion to the dashes.
Question. When transmitting at night, what is it necessary
Answer. Care must be taken to select a position not in the
immediate vicinity of or in line with other lights. All unneces-
sary lights in the vicinity of the sending station should be
Question. When are signals by flashing light to be executed?
Answer. (1) On the termination of the 10-second flash of the
(2) At the time designated in the signal.
(3) On arrival at the position designated in the signal.
(4) In the case of certain signals, as soon as made and
Question. What means may be employed in signaling by
Answer. (1) Searchlight.
(2) Yardarm blinker.
(3) Blinker tube.
(4) Any other effective method of displaying or projecting
Question. How should the searchlight be used?
Answer. At night the beam should be projected where it will
be most clearly distinguished by the receiving unit(s), but not
directly on the receiver. During daylight the searchlight must
be accurately trained on the receiving unit.
Question. To insure this being accomplished; what should be
Answer. Signal searchlights should be fitted with a sighting
Question. What is the most efficient method of transmitting
visual signals long distances?
Answer. The searchlight.
Question. What is the yardarm blinker?
Answer. It is an " all-around " light located at the yardarms
and operated by a key on the signal bridge.
Question. When should the blinker tube be used?
Answer. When circumstances render it advisable that a signal
light shall not be seen, except in the direction of the receiver.
The tube must be pointed directly at the receiver. When less
INSTRUCTIONS FOE COAST GUARD STATIONS.
brilliancy is required, as on clear, dark nights, the light may
be dimmed by veiling it with one or more thicknesses of bunt-
ing; this veil should be inserted well down the tube, in order
that radiance from it shall not be visible laterally.
Question. What procedure is prescribed for dispatches trans-
mitted by flashing light when transmitting to one unit?
(1) Repeats call as made by
(2) Repeats call as made by
transmitting unit (transmitting
(3) Answers with a flash.
(4) Answers with a flash.
(5) Answers with a flash.
(6) Answers each word
group with a flash.
(7) If dispatch has been re-
ceived makes R II VA.
(8) Receiving unit answers B
with R II X or R II Q, as circum-
(1) Makes call of unit for whom
dispatch- is intended several times
or until repeated.
(2) Makes own call until re-
(3) Makes break (II).
(4) Makes G-R followed by the
number of words or groups.
(5) Makes II if text is in plain
language ; BT if text is in code.
(6) Transmits text of dispatch
(including office and date number
and time of origin number).
(7) Makes "finale" sign
(8) If there are further dis-
patches to transmit to the same
receiving^ unit, transmitting unit
makes AR II B.
Question. Where is the proper location of prescribed procedure
signs indicated when their use is required?
Answer. In the example illustrating the various parts of a
dispatch (flashing light method, p. 220).
Question. When transmitting to one unit what does the omis-
sion of the answering flash indicate?
Answer. It indicates that the word or sign just made was
not received and that repetition is desired. The transmitting
unit should repeat the last word or sign immediately.
Question. W'hat is the semaphore system?
Answer. It is the standard system of transmitting dispatches
'uring daylight for short and medium distances.
226 INSTRUCTIONS FOR COAST GUARD STATIONS.
Question. Under ordinary circumstances would it be used for
the transmission of signals?
Answer. It would not; but it may be used either as the
primary method of transmission or as a secondary method to
supplement flag signals then displayed.
Question. Describe the flags used in transmitting messages
Answer. It employs two hand flags, from 15 to 18 inches
square, and either blue and white similar to the International
flag P or red and yellow similar to the International flag O,
the color to be used which affords the better contrast to the
background. Each flag should be attached to a light staff about
2 feet long.
Question. What attention should be paid to the background
when using semaphore ?
Answer. The sender should select a background giving the
greatest contrast. Except under special conditions of light and
when the sun is in line with and back of the sender, the sky
affords the best background.
Question. What care must be exercised in sending semaphore
Answer. The arms must be placed at the exact, positions indi-
cating the letters, a distinct pause being made at each position
and the arms moved from position to position by the shortest
Question. How is the semaphore alphabet printed?
Answer. As the characters appear with the sender facing the
receiver. Thus, the character B is with the right arm extended
Question. How are numbers sent by semaphore?
Answer. Numbers should always be spelled out.
Question. What is the "break" sign in semaphore?
Answer. The flags crossed in front of the center of the body,
as shown in the plate.
Question. What is the answering sign in semaphore?
Answer. The right-hand flag extended vertically upward and
the left-hand flag extended upward at an angle of about 45
as shown in the plate.
Question. What procedure signs ordinarily are used in sema
INSTRUCTIONS FOR COAST GUARD STATIONS. 227
Error E jgitated.
Interrogatory . ?!?
Code follows BT.
Signals follow IM7
Number of words or groups- GR (followed by number spelled out).
End of word Break.
End of sentence (full stop)__AAA" (thrte A's).
End of dispatch .AR.
Repeat all before word -IMI break AB break (word).
Repeat all after word -IMI break AA break (word).
Repeat word after word IMI break WA break (word).
Received (and communica- R break VA used only when call flags
tion finished). are not used. When call flags are used
fj? the hauling down of the call signifies
" dispatch received ") .
Move to your right MR. 7
Move to your left ML, 7
Move up MIT. 7
Move down MD. 7
Question. How would you call a ship or unit by flag hoist for
a semaphore signal or dispatch?
Answer. Hoist the call of the ship or unit for whom the
signal or dispatch is intended, "two-blocked" (unless it is
necessary to make such a call while flag signals are displayed
at the same yardarm, in which case the call may be hoisted at
Question. How does a unit so addressed answer?
Answer. By hoisting the call of the calling ship or unit over
the answering pennant (1) at the "dip," as soon as seen, and
until ready to receive; (2) two-blocked when ready to receive.
Question. What should be done to enable the receiver to
locate the signalman?
Answer. The " attention " sign should always be made by
the transmitting unit when several signalmen are sending to
a large number of units, to give the receiver an opportunity
to locate the sending signalman.
Question. How would you call a ship or unit without flag
hoist for a semaphore signal or dispatch?
Answer. There is no equivalent for the call pennants in sema-
phore. When it is not practicable to call by flag hoist, and the
r May be used in wigwag also.
INSTRUCTIONS FOR COAST GUARD STATIONS.
" attention " sign is not sufficiently definite, three or four letters
abbreviating the unit's name will be used as a call.
Question. How will the unit addressed answer?
Answer. It makes the "answering" sign, and if that be not
sufficiently definite, the three or four letters abbreviating the
name of the unit answered.
Question. How may you be assured that a semaphore mes-
sage has been received?
Answer. Any desired degree of assurance that the signal has
been received may be attained by the use of prescribed pro-
cedure signs. Thus, if the call is followed by
(1) G, the receiving unit will repeat back.
(2) Y, the receiving unit will acknowledge.
(3) G and Y, the receiving unit will repeat back and
Question. What procedure signs are used in semaphore?
Answer. The procedure signs prescribed for Morse are to be
used when required. When used, their position in the dispatch
corresponds to their position when used in systems employing
Question. What procedure is prescribed for the transmission
of dispatches by semaphore?
Answer. The procedure is as follows :
TRANSMITTING UNIT. RECEIVING UNIT.
(1) Makes call, either by flag (1) If the call be by flag hoist
hoist and attention, by " atten- answers call by hoisting answer-
tion " alone, or by attention fol- ing pennant under the call of the
lowed by letter or letters abbre- transmitting unit at the dip, as
viating the name of the unit for soon as seen, and two blocked
whom the dispatch is intended. when ready to receive and record.
If the call be other than flag
hoist, makes the " answering "
sign, followed, if necessary, by
three of four letters abbreviating
the name of the transmitting unit.
(2) When confusion might arise (2)
as to which unit the dispatch is
being transmitted, makes the let-
ters abbreviating the name of the
receiving unit. When there is no
possibility of confusion this may
Makes break. (3)
(4) Makes G-R followed by num- (4)
ber of group or words.
(5) Makes break. (5)
INSTRUCTIONS FOR COAST GUARD STATIONS. 229
(6) Makes 1&T followed by
" break," If text is in code.
(7) Proceeds with text of dis-
patch, all numbers being spelled
(8) Makes break.
(0) Makes AR, and hauls down
the flag call if used.
(7) When the call and answer
is by flag hoist, the answering
pennant is to be dipped immedi-
ately a word or sign is missed.
If the call be other jthan by flag
hoist, makes repeat (IMf).
(9) Acknowledges the receipt of
the dispatch (a), if the call and
the answer be by flag hoist, by
hauling down the answering pen-
nant when the transmitting unit
hauls down the call; (&) if the
call and answer be other than by
flag hoist, makes " R break vT."
Question. How is the failure to receive a word or sign indi-
Answer. (1) If the call and answer be by flag hoist, by the
receiving unit dipping the answering pennant.
(2) If the call and answer be other than by flag hoist, t>y the
receiving unit making the repeat sign IM!.
Question. On receipt of a dispatch, if the call and answer be
by flag hoist, what does the receiving unit do?
Answer. It hauls down the answering hoist.
Question. If during 1 the sending of the dispatch the receiving
unit fails to receive any part of it for any reason, such as sen-
der becoming obscured by smoke, etc., what should the receiv-
ing unit do?
Answer. It should dip the answering pennant. The sending
unit should then dip the call. When the receiving unit is again
ready to receive, she should two-block the answering pennant.
The sending unit should then two-block the call and proceed
with the dispatch, starting with and repeating the last two or
three words transmitted before the answering pennant was
Question. If the receiving unit requires more than the last
word or sign to be repeated, what should it do?
Answer. It should make the appropriate procedure sign for
repeating the required portion.
Question. What alphabet, etc., is employed in wigwag?
Answer. The International Morse alphabet, numerals, and
special. Morse signs.
230 INSTRUCTIONS FOR COAST GUARD STATIONS.
Question. How is a dot and a dash represented?
Answer. A motion through an arc of 90 degrees to the sen-
der's right represents a " dot," and a similar motion to the left
a '* dash."
Question. What signs are peculiar to wigwag?
Answer. The only signs peculiar to wiwag are :
(1) The "attention" sign, i. e., the flag waved back and
(2) The " break " sign, i. e., a motion to the front.
Question. What may be used in signaling by wigwag?
Answer. A hand flag, a hand light, or a searchlight beam.
Question. What should the sender do in sending a message?
Answer. He should face the receiver squarely. The motions
for the dot and dash should be made at right angles to the line
of transmission, and for the " break " from the vertical position
through an arc of 135 in the direction of the line of transmis-
Question. What should be done to keep the flag fully ex-
Answer. The point of the staff should be made to describe
an elongated figure 8.
Question. What is desirable in case a hand light is used?
Answer. It is desirable to have a reference light at the send-
Question. How may an oil lantern be used?
Answer. It may more conveniently be swung outward and
Question. What is it important to do in sending by wigwag?
Answer. It is important to obtain a good background and to
select a flag the colors of which present the most marked con-
trast with the background.
Question. How may the prescribed calls be supplemented?
Answer. The prescribed calls may be supplemented by flag-
hoist calls, as in semaphore. The procedure prescribed for
semaphore shall be followed.
Question. Can wigwag be seen as far as semaphore?
Answer. A large wigwag flag against a good background may
be read at a greater distance than semaphore.
Question. For what is sound signaling prescribed?
Answer. For use in thick weather under circumstances where
the use of radio is inadvisable and when such signals \yill not
INSTRUCTIONS FOR COAST GUARD STATIONS.
be confusing to strangers in connection with the " rules of the
road," or confusing to our own ships in connection with the