Chapter - 19

Signaling

Various forms of signal codes have been used by manners for many years, but these have not always been international in scope. The need for such a universal system by which ships of all nations could communicate with each other without misunderstanding was brought into sharp focus during the World War of 1914-1918. At that time the International Code of Signals proved inadequate. Revisions were therefore made and a new code drafted, which has now been in general use the world over for a number of years.

In the field of pleasure boating, flags of the International Code are most commonly seen as a decoration for yachts when they dress ship at regattas, on holidays, and so on—much less frequently in the use for which they were basically intended, that of conveying messages from one ship to another. Yet if boatmen were more generally aware of how valuable the ability to signal to other craft might be at times, it is likely that they would regard a knowledge of the fundamentals, at least, an indispensable part of their education in seamanship.

How important a more general knowledge of correct signaling technique among vessels of all kinds really is, is evidenced by the fact that ships of the Navy and Merchant Marine regularly communicate at sea with the express idea of gaining familiarity in the use of the code. Much could be accomplished if yachtsmen as a group would also seize every opportunity to familiarize themselves with its correct use.

As a matter of fact, the former Bureau of Marine Inspection and Navigation once reported that, due to cooperation of the Navy, the Maritime Commission, and the Coast Guard with the Bureau, there has been a definite improvement in signaling efficiency on the part of Merchant Marine personnel. For a time the Bureau in its monthly bulletin carried a list of the contacts made between merchant ships and vessels of the Navy and Coast Guard, but within a year they reached such volume that it was no longer practicable to publish it.

For a full, complete explanation of the fundamentals to be outlined in this chapter, yachtsmen are referred to H. O. No. 87, a publication of the Hydrographic Office of the Navy Department—entitled International Code of Signals (Volume I, Visual and Sound). It may be obtained from the Hydrographic Office at Washington, D. C, or any of its agencies in principal cities. A separate volume deals with radio communication. A copy of H. O. No. 87 and a good set of signal flags should be part of the equipment, not only of every seagoing yacht, but all pleasure boats from fair sized cruisers up. On yachts of the Coast Guard Auxiliary they would be particularly desirable.

Methods Of Flag Signaling

There are four common methods of communicating by means of visual signals. These include: (1) flag signaling, with the use of International flags and pennants; (2) flashing light signals; (3) sound signals and (4) the use of semaphore signals. For the second and third methods, the International Morse Code is used.

Flags of the International Code include 26 letter flags, 10 pennants for numerals, 3 substitute or repeater flags, and a code or answering pennant.

In the second and third methods, using flashing light or sound signals, combinations of dots and dashes constituting the International Morse Code express the various letters, numerals and signals. In determining the duration of dot and dash signals, the dot is taken as a unit, a dash equals three units, and the time between any two elements of a symbol is equal to one unit. Between two complete signals, the interval is three units; between two words or groups, five units. This spacing of the letters, words, etc., is an important element of successful signaling.

Flashing light signals are commonly made by exposing and obscuring a light. Sound signals can be made on a siren, whistle, fog horn or any other sound apparatus. Eight words per minute is taken as standard for flashing light signals.

Semaphore signals are made by a signalman holding a pair of hand flags in various positions to designate letters of the alphabet, etc. This is not to be confused with the wig-wag system of flag signaling. As in flashing light signaling, standard practice requires signaling by semaphore at the rate of eight words per minute.

If every message transmitted by means of visual signals had to be spelled out letter for letter, it is apparent that the procedure would become tedious; wasting much time and effort. For this reason, by the use of the code given in H. O. No. 87, words, phrases and even sentences are reduced to a few simple letters. Obviously then one of the first essentials in gaining proficiency in signaling is to be thoroughly conversant with the code book. With such knowledge one will naturally frame his messages so as to utilize phrasing for which code letters have been provided.

In the exchange of messages it is always assumed that the communication is between the masters of the two vessels, unless expressly stated to the contrary.

Signal letters assigned to ships consist of four letters, of which the first letter or two indicate nationality. These agree with their radio call signs. The same principle applies to aircraft except that the signal letters and radio call signs consist of a five-letter group. It should be noted that these letters are used in two ways. Where a ship, aircraft or signal station is spoken to or is called, the signal letters precede the communication or signal. But when a signalman wants to speak of a ship, that is to say, indicate or refer to a certain ship in his message, he uses her signal letters at the end of his signal.

Spelling Out Words

Not all messages are sent in code; they may be expressed in plain language, spelling out words in full. When ships are referred to in a coded message, their signal letters are used, but when the message is in plain language, then the ship's name is spelled out.

Sometimes, in plain language messages, numbers are written out in full as words in order to eliminate any possibility of error—for example, "one two three" in place of "123." Another safeguard against error, in plain language messages, is to repeat the number, indicating the fact by the word "repetition" directly preceding such repetition—for example, "one two three repetition one two three."

The manner of signaling numbers varies with the method used. In flag signaling, numeral pennants are provided, the shape of which distinguishes the numbers from the letters. In Morse signaling (flashing light or sound), numerals are provided for with distinctive signals, though they may be spelled out. In semaphore, numbers are spelled out. If a decimal point occurs between numerals in a flag signal, the answering pennant is inserted to express it. In Morse, the decimal point sign is the same as a period (. — . — . —). In semaphore it would be spelled out "decimal."

In some cases numbers must be added to a code group to complete its signification. Except when signaling time, bearings or positions, the numbers in such cases are sent as a separate group.

Time On Shipboard

In navigation, time is expressed in terms of hours up to 24, rather than 12 for A.M. and 12 more for P.M. In signaling the same principle applies, so that any time can be expressed in four figures. For example, 2:10 A.M. becomes 0210; 3:12 P.M. would be 1512. In signaling a coded message, the letter T would be joined with these four numerals to form a single group and indicate that the numerals express time—for example, T0210 or T1512. The T always precedes the numerals. In plain language messages (as differentiated from code) the context makes it clear when the message relates to time.

Sometimes the time is signaled from one vessel to another as a check on the chronometer time, in which case the exact instant becomes very important. This is handled by having the time relate to the instant when the signal is hauled down and, if this is done smartly, the time can be checked to a split second. If the message happened to be in Morse, the exact instant would be indicated by sending a long (5-second) dash after the time signal, the end of it synchronized with the exact time which the four-numeral signal expresses.

Courses and bearings are signaled by three figures, interpreted as true, unless expressly designated as magnetic. For example, a course of 45 degrees true would be simply 045; if it is to express a magnetic course of 45 degrees, then the signal would be 045 magnetic. When a course is signaled in code, a suitable code group to express the desired idea would be followed by the three numerals. In the case of a bearing, the letter X is joined to the numerals to form a single group, the X preceding the numerals. X045 would therefore signify "bearing 45 (true)."

Inasmuch as wind and current are often referred to in terms of points of the compass, three-letter code groups have been provided for each of the 32 points. The more or less long-winded Southwest By South is thus cut down, in code, to NTT; Northwest By West to JUV.

To Signal Position

To signal a position by giving the latitude and longitude, each would be expressed as a group of four figures, the first group indicating the latitude, the second the longitude. In each case the first two figures indicate degrees; the last two, minutes. When making a signal, each of the two groups of figures would be joined and preceded by the letter P. P4027, P7400 would thus indicate a position in latitude 40 degrees 27 minutes, longitude 74 degrees 00 minutes.

Commonly, it is unnecessary to indicate whether the latitude is north or south and the longitude east or west, since in most cases both are obvious. If required to avoid confusion or misunderstanding, then the N or S can be added directly after the latitude numerals and the E or W directly after the longitude figures. This is often desirable in cases where the position is in a latitude close to the equator or the longitude close to 0 or 180 degrees.

When the longitude runs into three figures, it is usually expedient to drop the first figure since a ship invariably knows her position to the nearest hundred degrees. By doing this, any longitude can be expressed by a four-figure group, though five may be used if necessary to prevent misunderstanding.

Another method of expressing position is by bearing and distance from a given point. In signaling a position by this method, a certain sequence must be observed as follows: first, the bearing from; second, the distance from; third, the point. Thus X021—15—Point Blank would be interpreted as a position 15 miles 21 degrees true from Point Blank. The letter X and three figures will be recalled as expressing the bearing; the 15 group is taken to mean miles unless otherwise stated. The geographical position of the point might be given as a four-letter group from the code book. If, instead of a geographical point, the point of reference happened to be a ship, its position being known, the final group would be the signal letters of the ship referred to.

The time of origin of a message is considered to be the time at which a message is ordered to be made. When it is necessary to insert this time in a signaled message, it is put at the conclusion. The time is expressed in four figures, to the nearest minute. Certain local codes are in use which do not conform to the International Code. Misunderstanding might arise if such local codes were used without explanation. Consequently provision is made for such signals by displaying first the International NMM. This will make it clear that the signals following are not to be interpreted from the International Code book.

Code Flags

When signaling by means of the flags and pennants of the International Code, it is advisable to show only a single hoist at a time. A hoist means one or more groups displayed from a single halyard. The signal is read from top to bottom. (However, in certain organizations, where secrecy is desired, the signal is read from the bottom up. This may explain some strange signal not found in the code book, if read top to bottom.) Each group of letters and/or numerals constitute a separate signal and when several groups are used on one hoist, they naturally must be separated to convey the right meaning. A tackline, consisting of a piece of halyard about 6 feet long, is used to separate such groups.

Signals should be kept flying until answered. There are occasions when more than one hoist may be displayed simultaneously and then an order of sequence must be followed in order to interpret the message correctly. In such cases the hoists are read in the following order: (1) masthead, (2) triatic stay, (3) starboard yardarm and (4) port yardarm. (The triatic stay runs from the main to the foremast head.)

In cases where more hoists than one are flown from a yardarm, the outboard hoist is read first; where more than one are displayed at the triatic stay, the one furthest forward is read first.

The terms superior and inferior are often used in relation to signals. A signal is superior to another if hoisted before the latter, either in point of time or hoist. If hoisted after, it is inferior.
 
Obviously a visual signal is going to fail of its purpose if it is not clearly visible. For that reason signals should always be flown where they can best be seen by the receiving vessel. This means that each flag must stand out clearly, not enveloped in smoke or fouled by sails, rigging, etc.

How To Call

When calling a particular vessel, her signal letters are hoisted superior to the message which is to follow; otherwise, in the absence of such signal letters, the message would be understood to be addressed to all vessels in sight of the signal. If the other vessel's signal letters are not known, she can be directed or requested to hoist them by displaying the code letter group VH and hoisting the transmitting ship's own signal letters at the same time. As a final alternative, display of the code group NMJ would convey the message: "I wish to signal to the vessel(s) on bearing indicated from me" and, of course, the bearing would be given to distinguish between several vessels which might be within signaling distance.

In order to understand the procedure followed in answering a signal there are several terms which should be defined. A signal is at the dip when hoisted only about half the extent of the halyard; it is said to be close up when hoisted to the full extent of the halyard.

In answering a signal then every vessel addressed should hoist the answering pennant at the dip as each hoist is seen, closing up to indicate that the signal is understood. Then when the transmitting ship hauls her hoist down, the answering pennant on the receiving ship is immediately lowered to the dip again so as to be ready to acknowledge the next hoist, in similar manner, when understood. This continues until the message is completed. (It is suggested that the triatic stay should not be used for the answering pennant because of the difficulty in distinguishing whether it is at the dip or close up.) When the transmitting ship has lowered the last hoist, she indicates that the message is complete by hoisting the answering pennant alone, which the receiving ship answers just the same as all previous hoists.

When a signal cannot be clearly distinguished, the receiving ship keeps the answering pennant at the dip and hoists a signal which will convey the reason for the difficulty. If, on the other hand, she can distinguish the signal but does not understand its meaning, she flies the code signal VB indicating: "Signal is not understood though flags are distinguished."

Repeaters Or Substitutes

With every set of code flags are included three pennant-shaped repeaters or substitutes. These permit the signalman to repeat the same signal flag in a group without carrying extra sets of flags. These substitutes repeat the same class of flag that precedes them; that is, following alphabetical flags they repeat them—but if used with numeral pennants they repeat such pennants.

Considering then only the class of flags directly preceding the substitute, the first substitute repeats the top flag; the second substitute, the second flag from the top; and the third substitute the third flag from the top. An answering pennant used as a decimal point is disregarded and a substitute is never used more than once in the same group. If, for example, the signal to be made is ABBA, the hoist reading from top to bottom would be: A, B, second substitute, first substitute. If the signal were 5222, the hoist would be 5, 2, second substitute, third substitute. Note that the second substitute has been used in place of the third numerical and cannot be used again. However, it represents the 2 of the third numeral, therefore the third substitute is used to repeat 2 in the last numeral. T1550 would be signaled T, 1, 5, second substitute, 0, since the substitute in this mixed group of a letter and numerals follows a numeral and therefore repeats the second numeral, which is 5.

When names occur in the text of a message they are spelled out, and alphabetical signals are provided having certain significations. The answering pennant over E (alphabetical signal number 1) indicates that until alphabetical signal number 3 is made, the letters which follow do not represent code signals but alphabetical letters spelling a word. Answering pennant over F (alphabetical signal number 2) signifies the end of a word being spelled or a dot between initials. Answering pennant over G (alphabetical signal number 3) means that the spelling is complete and the signals which follow should be interpreted from the code book.

When naval vessels communicate with merchant ships, they hoist the code pennant and keep it flying while the signal is made. When signal exercises are engaged in between such vessels, or between mer-chantment, the code group NMI is used to express: "I wish to exercise signals with you." NML indicates that the "signal exercise is finished."

Morse Code

At this point it would be well to refer to the illustration of the Morse symbols used for both visual and sound signaling. Included in this illustration are some of the more important procedure signals.

These procedure signals and signs are in the nature of abbreviated messages, that is, they enable ships to exchange short, concise messages used frequently in connection with signaling.

Learning The Code

It is important that the Morse Code be learned by every sailor so that messages by blinker-light (and sound) may be sent and received.

The Coast Guard and the Merchant Marine teach the alphabet by letter from A to Z. It has been found that many learn faster by having the alphabet divided into groups of similar combinations as suggested below:

E (ECHO).                                           A (ALFA) . —
I (INDIA) . .                                        U (UNIFORM) .. —
S (SIERRA) ...                                     V (VICTOR) . . . —
H (HOTEL) ....
T (TANGO) —                                    N (NOVEMBER) — .
M (MIKE)――                                   D (DELTA) — . .
O (OSCAR) ―――                           B (BRAVO) — ...
A (ALFA) .—                                      N (NOVEMBER) — .
W (WHISKEY). ――                                     G (GOLF) ――.
J (JULIETT) . ―――                                      Z (ZULU) ――..

The balance of the alphabet is:

C (CHARLIE)—. — .                         Q (QUEBEC) ――. —
F (FOXTROT).. — .                           R (ROMEO). —.
K (KILO) — . —                                X (X RAY) — . . —
L (LIMA) . — . .                                  Y (YANKEE) — . ――
P (PAPA) . ――.

Of these R, L and P might be grouped; K, C and Y; leaving only F, Q and X not well related.

Procedure Signals

Some of the important procedure signals are as follows:

The letter C (—. — .) means "You are correct."

De (—.. .) in the identity means "From ." For example, De GXDE means "From ship whose signal letters are GXDE."

G (――.) means "Repeat back." This may be used as a separate signal at the beginning of a plain language message and then signifies that everything which follows should be repeated back, word by word, as received.

R (. — .) means "Message received."

T (—) signifies the receipt of each word in the text of a plain language message.

W (.――) means "I am unable to read your message owing to light not being properly trained or light burning badly." The receiving ship may make this W signal at any time, in which case the transmitting ship should show a steady light until the receiving ship indicates that she is satisfied with the light by stopping the W signal.

AA AA, etc. (. —. — . — . — etc.) is the call for an unknown ship and general call, used to attract attention before signaling a ship the name of which is unknown. It is discontinued when the ship called answers.

TTTTT, etc. (― ― ― ― —etc.) is the signal used to answer the above call, discontinued when the transmitting ship stops calling.

Note: A bar over letters composing a sign means the letters are to be made as one symbol.

UD (..― ―..) is the repeat sign, used to request repetition of all or part of a message. When it is made singly it means "Repeat the last message." In sound signaling the repeat sign made singly means "I missed the last word (or group); please go back a few words (or groups) and continue the message."

Using The Repeat Sign

The repeat sign UD may be used in conjunction with the signs AA, AB, WA, or WB and an identifying word or group, the last two separated by the space sign. The space sign is II (....) and is used not only in conjunction with the repeat sign but also to separate whole numbers from fractions.

The letters AA, AB, WA, and WB have the following significance: AA (. — .—) all after.
AB (.――...) all before.
WA (.――.—) word or group after.
WB (.―――...) word or group before.
Thus,
UD (alone) means "Repeat the last message."
UD AA II VESSEL means "Repeat all after the word VESSEL."
UD AB II JEM means "Repeat all before the group JEM."
UD WA II KIC means "Repeat the group after KIC."
UD WB II FLAGS means "Repeat the word before FLAGS."
 
Repeat signs are not to be used when a message is not understood or when a message as decoded is unintelligible. In such cases, suitable signals taken from the code should be made.

Other Signs

The break sign BT (— ... —) is used to precede text. It is repeated back but its repetition by the receiving ship is not acknowledged with C by the transmitting ship. (This is amplified under Flashing Light Signaling.)

EEEEE, etc. (   etc.) is the erase sign, signifying that the last word or group was signaled incorrectly. It is answered with the erase sign. When answered, the transmitting ship repeats the last word or group correctly signaled and then goes ahead with the rest of the message. In the event that the error is not discovered till the message is complete, then the entire message must be signaled over again correctly.

AR (. —. —.) is the ending sign used to end all messages. If a whole message is to be cancelled while it is in process of transmission, the correct procedure is to make the erase sign and follow it with the ending sign, thus: EEEEE AR.

PRB is the international code group indicator, used in messages transmitted by Morse code as the first group of coded text and signifies that the message which follows consists of code groups, not plain language.

Flashing Light

When signaling by flashing light, messages are divided into five component parts: (1) call (2) identity (3) break sign (4) text, and (5) ending. However, it does not follow that all these components will be found in every message,

The call, which begins a message, consists either of the general call (AA AA etc.) or the signal letters of the ship being called. When the receiving ship is ready to take the message, she answers by making the answering sign.

When it is necessary for the two ships to establish their identity, it is done as follows: After the call is answered the transmitting ship makes "de (from)" followed by her signal letters. This is repeated back. Then the receiving ship makes her own signal letters and the transmitting ship repeats back. In the event that either does not repeat back, or does so incorrectly, tl en the other makes her signal letters again until they are correctly repeated back.
 
The break sign, as previously indicated, is BT and is signaled next, preceding the text which follows. It is repeated back, but the transmitting ship does not acknowledge its repetition by the receiving ship by making the C signal (You are correct) because this is not part of the text of the message. Should the receiving ship fail to repeat back the BT (break) signal, the transmitting ship must make it again, until properly acknowledged. When the message requests a repetition, the break sign is not used before the text.

The fourth component is the text. This may be in plain language words or in groups of code, each word or group being signaled separately. As each plain language word is received, the receiving ship acknowledges it by making T. In the case of code groups, numbers (in figures, not spelled out), procedure signals, and signs (except C and punctuation signs) she repeats back as each is made and if such repetition is correct, the transmitting ship makes C. If the repetition is incorrect, then the transmitting ship must make the group again. Similarly, if the receiving ship does not acknowledge receipt of the signal or repeat back, then the transmitting ship must make the last word or group again.

As mentioned in the summary of procedure signals and signs, the ending sign is AR. This is the fifth and last component of the message, made at the end of the text and answered by the receiving ship by R (Message received).

Naturally when ships are exchanging a series of messages, there would be nothing gained by including the call and identity (the first two components) each time. Consequently they would be used at the beginning of the first message but omitted from subsequent messages.

The International Code Book gives many examples of how various types of messages would be exchanged by flashing light, for example: plain language, a coded message, a message with identity omitted, a message with both call and identity omitted, a repetition of a whole message, repetition of "all after" a certain group, repetition of "all before" a certain word, repetition of the "group after" a certain group, and repetition of the "word before" a certain group. The signals made by both transmitting and receiving ships are given, in the proper sequence. The following are given as examples of (1) a simple plain language message and (2) a coded message:

(1) The master of S.S. Malolo (signal letters WMCE) wishes to transmit the message "What weather have you had ?" to the master of a passing ship, which is S.S. Accra (signal letters GMON). The signaling is conducted as follows:
 
Component         S.S. Malolo               S.S. Accra             References
                           Makes                       Makes                    And Remarks

 (2) The Italian warship Solferino (signal letters IASJ) wishes to transmit the message "Have you sighted S.S. Fausto?" to the American merchant vessel Michigan (signal letters KFLN). The message is coded and the signaling is conducted as follows:

Note: The references in the last column of these tabulations relate to article numbers in H. O. No. 87.

Sound Signaling

Sound signaling should be used only with the greatest of caution, due to the confusion it might create with passing or fog signals. A good rule for yachtsmen would be to become thoroughly familiar with its principles and procedure but never to use it except in emergencies or in cases where there is certainty that no misunderstandings could possibly arise as a result of its use.

A sound signal should be as brief as possible and, except in emergency, communications should be limited to the single-letter signals. In fog or in inland waters where traffic is heavy, sound signals must be kept to an absolute minimum.

When necessary to signal by sound—on whistle, siren, fog horn, or other appliance—the call is made the same as by flashing light (AA AA ÀA, etc.). However, no call or answer is used with single-letter signals.

The receiving ship answers a call with the answering sign TTTTT, etc., after which the transmitting ship signals her complete message, with no acknowledgement, repetition or interruption from the receiving ship unless the latter happens to miss a word or group. In that case the receiving ship may break in immediately with the repeat sign (UD), whereupon the transmitting ship would make the last few words or groups over again and continue. When the transmitting ship has completed the message she makes the ending sign (AR), acknowledged by the receiving ship with the final R (Message received).

The code book gives the following example of a communication carried out in Morse signaling by sound. Although the general call is used, the ships do not exchange identities.

S. S. Beechwood, hearing the sound of another steamer's siren, wishes to transmit the message: "Have just passed floating mines." The other ship is S. S. Sirius.

Component                     S.S. Beechwood          S.S. Sirius Makes
                                       Makes

Call                                  AA AA AA, etc.         TTTTTTT, etc.
Break Sign                       BT
                                       Have                            1 No answer unless a word
                                       just                               is missed, in which case
Text                                passed                         
                                       floating                         makes repeat sign UD.
                                       mines                            See article 121.
Ending                             AR                               R

Semaphore

When a ship wishes to communicate by semaphore (hand flags) she hoists the International Code flag J, a single-letter signal, which means: "I am going to send a message by semaphore." This may be hoisted singly or inferior to a group of signal letters. When the ship addressed sees this, she first hoists the answering pennant at the dip, then close up when ready to take the message.

To designate which one of several vessels is to answer the signal, the semaphore flag is hoisted with a tackline inferior to the signal letters of that ship. A naval vessel wishing to signal by semaphore to a merchantman would hoist the code pennant where it could best be seen, and the merchant ship's signal letters with a tackline superior to the semaphore (J) flag. The semaphore flag flies until the message is completed.

To signal by semaphore, a signalman takes two square hand flags and, using the semaphore alphabet, spells out a plain language message, numbers as well as words being spelled out in full.

First the sender makes the attention sign (waving both flags at arm's length), whereupon the receiving ship should hoist the answering pennant close up. If necessary, the sender then makes the name of the receiving ship, followed by "de (from)" and the name of the transmitting ship. Frequently vessels communicating by semaphore are relatively close to each other. Then, instead of hoisting the semaphore (J) flag and answering pennant, the attention sign and the answering sign (C) may be used.

In signaling, the signalman faces the ship addressed and as each word is completed drops his arms to the position designated for the break sign. The break sign is also used in spelling double letters; the first letter is made, arms dropped to the break position, and then immediately moved to the second letter. Each word is acknowledged aboard the receiving ship by making C (the answering sign), and if not so acknowledged the word is repeated. When an error is made, the sender makes a succession of E's (EEEEEEE, etc.) then signals the last word that was made correctly and continues his message. The message is completed with the ending sign AR.

The code book gives the following example of a message sent by semaphore:

The master of S. S. Lurline (signal letters KIEK) wishes to transmit by semaphore the message: "Can you loan me a kedge anchor?" to the master of S. S. Stora (signal letters GDVR).

Naming The Flags

To avoid any possibility of error when calling off flags or pennants, the Navy has a system of naming each flag. Thus one could not mistake a B for a V or an M for an N, etc. Their names are:

A—Alfa           H—Hotel               O—Oscar              V—Victor
B—Bravo        I—India                 P—Papa                W—Whiskey
C—Charlie       J—Juliett                Q—Quebec           X—X Ray
D—Delta         K—Kilo                 R—Romeo             Y—Yankee
E—Echo          L—Lima                S—Sierra               Z—Zulu
F—Foxtrot       M—Mike               T—Tango
G—Golf           N—November       U—Uniform

Signal Code

Much of Volume H. O. No. 87 is necessarily devoted to a listing of the various code letters and groups, with their significance. All signals consist of single, two, three or four letters. Single-letter signals are urgent messages or those in common use. Two-letter signals are next in importance, including distress and maneuvering signals and some general signals in common use. Three-letter signals are used for other words, phrases and sentences. Four-letter signals beginning with the letter A relate to geographical positions. Other four-letter signals are the signal letters of ships, signal stations, etc.

Call letters of ships may be identified from three publications: Signal Letters of the U. S. Merchant Marine, the Berne List, and Lloyd's Register of Shipping. The first of these is available from the Superintendent of Documents, Washington, D. C. (15c). The Berne List is primarily for radio and Lloyd's Register is a large volume generally found in shipping offices but not on shipboard.
 
The problem of compiling a code from which expressions in any one of seven foreign languages might be taken was a difficult one and certain principles must be followed in its use. These are outlined in the instructions which accompany the code and should be carefully read before attempting to use the code itself. Otherwise, because of the form used, erroneous interpretations might be placed on a message sent in code. Numerous examples help to make the practice of coding clear.

The following brief list of some of the one- and two-letter signals, taken at random from the complete code as given in H. O. No. 87 will serve to indicate how easily a yachtsman with only an elementary knowledge of signaling procedure could transmit important messages to other craft cruising in his company or to passing vessels.

Typical Code Signals

C         Yes (Affirmative).
D         Keep clear of me—I am maneuvering with difficulty.
F          I am disabled. Communicate with me.
G         I require a pilot.
N         No (Negative).
O         Man overboard.
P          In Harbor (Blue Peter)—All persons are to repair on
            board as the vessel is about to proceed to sea. (Note:
            To be hoisted at the foremast head.)
            At Sea—Your lights are out, or burning badly.
Q         My vessel is healthy and I request free pratique.
U         You are standing into danger.
V         I require assistance.
W        I require medical assistance.
AM      Accident has occurred. I require a doctor.
AP       I am aground.
CU       Anchorage is dangerous.
DO      I am drifting and require assistance.
DQ      I am on fire and require immediate assistance.
DV       I have sprung a leak and require immediate assistance.
DZ       I require immediate assistance.
EU       Bar is dangerous.
FV       It is impossible to land.
JT        You should follow me, or vessel indicated.
JZ        I have damaged my rudder. I can not steer.
LJ        I am disabled. Will you tow me in or into place indicated ?
LO       My engines are disabled.
LP        My steering gear is disabled.
LT        I am dragging. Can veer no more cable and have no more
            anchors to let go.
LV       I am in distress for want of fuel.
NC      I am in distress and require immediate assistance.
PT        I require a pilot.
QW     I have on board mail for you, or vessel indicated.
RG       I have telegram (s) for you.
RH       Message has been received.
RJ        Have you any message for me?
RS       Is all well with you?
RV       Where are you bound?
RW      Where are you from?
SD       I am short of lubricating oil. Can you supply?
SE        I am short of petrol. Can you supply?
TH       I have lost my propeller.
TK       I require provisions urgently.
UW      I can not distinguish your flags.
VB       Signal is not understood though flags are distinguished.
WU      What course should I steer to make nearest land?
XY       Can you take me in tow?
YJ        I require water immediately.

Yacht Club Signal Codes

Yacht clubs have adopted signal codes of their own, which are not in conformity with signals prescribed by the International Code Book. Furthermore, since the practice among the clubs may vary to a certain extent, the interpretation of such club signals depends largely on a knowledge of the local code as prescribed in the club's year book.

The purpose of the signals prescribed in club codes is principally to provide a means of communication between vessels of the squadron. While the codes do vary, there is a tendency toward standardization of both the meanings of the signals and also the signaling procedure.

In general, signals in the club code will consist of: Special, racing and emergency signals (one or two flags, from A to Z, and A to AZ) ; general signals (two flags, BA to GZ); designation (two flags, HA to HZ); days of the week (two flags, IQ to IZ) ; hours of the day (two flags, JA to KY); names of places (two flags, NA to WZ); and compass signals (three flags, AQD to AST).

Most clubs provide that yachts using their own club code should hoist the club burgee over the club code flags; otherwise, absence of the burgee would indicate that the International Code is used.

Signaling Naval And Coast Guard Vessels

There may be occasions, particularly in time of war, when it is necessary for a pleasure craft to approach a Naval or Coast Guard vessel for the purpose of transmitting vital information. Obviously, no vessel of these services should be bothered with messages unless they are of consequence—dealing, for example, with national defense, or the safety of persons, property, or vessels.

When such a vessel is under way, she should be approached with signal flags flying—the International Code answering pennant at one yardarm, and the three-letter group JGI (urgent message) at the other. By the display of the International Code answering pennant, the naval vessel will understand that the signal is International Code, not Navy Code.

When the naval vessel is ready to receive the message it will hoist the (International Code) answering pennant, after which the message should be completed promptly with International Code Flag hoists.

When Signaling Equipment Is Not Available

On craft where signaling equipment is not available, attention may be attracted by waving a flag or any form of pantomime that will convey the idea of a desire to communicate a message. However, if warned by the naval vessel to stand off, the approaching craft should obey instructions regardless of the nature of the message, as naval craft are on serious business, and they may have their own reasons why no craft are to come near.

At night, all lights should be lit, the ensign displayed with flashlight or searchlight played upon it to make it conspicuous and easily identified, and approach should be slow and deliberate, always mindful of the possibility of being warned to stand off. Approach at all times should be toward the starboard side, about where the gangway is located.

If allowed to come alongside, the person in command of the small craft should establish his identity at once, state his business briefly (communicating only to proper officials), follow any instructions exactly, and depart only after permission is secured. Messages should be given only to the Commanding Officer or, in the case of large vessels, the Officer of the Deck.

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