信号旗组合代码及代码的意思船舶配备的五颜六色国际信号旗在组合上能表达各种内涵和意义。
（1)单字母信号（single-letter signals)
单字母信号适用于任何通信方法，26个英文字母除“R”外，每一个字母都代表一个完整的意义。单字母信号用于最紧急的、最重要的或者最常用的通信。例如：
A——我下面有潜水员，请慢速远离我；
*I have a diver down; keep well clear at slow speed.
B——我船正在装、卸或运载危险货物:
* I am taking in, or discharging, or carrying dangerous
goods.
C——是（表示许可);
* Yes (aftirmative or "The significance of the previous
group should be read in the affirmative").
D——我操纵困难，请避开我;
* Keep clear of me; I am manoeuvring with difficulty.
E——我正在向右转向;
* I am altering my course to starboard.
F——我机器失灵，请和我轮联络;
* I am disabled; communicate with me.
G——我需要引航员;
* I require a pilot.
When made by fishing vessels operating in close
proximity on the fishing
grounds it means: "I am hauling nets".
H——我船上有引航员;
* I have a pilot on board.
I ——我正在向左转向;
* I am altering my course to port.
J——我船失火，并且船上有危险货物，请远离我;
* Keep well clear of me. I am on fire and have dangerous cargo on board, or I am
leaking dangerous cargo.
K——我希望与你通信;
* I wish to communicate with you.
L——你应立即停船;
* You should stop your vessel instantly.
M——我船已停，并已没有对水速度…….
* My vessel is stopped and making no way through the
water.
N—否定
* No (negative or "The significance of the previous
group should be read in the negative"). This signal may
be given only visually or by sound. For voice or radio
transmission the signal should be "NO".
O——有人落水
* Man overboard.
P——在港内，本船将要出海，所有人员应立即回船。
* In harbour. All persons should report on board as the
vessel is about to proceed
to sea.
At sea. It may also be used as a sound signal to mean:
"I require a pilot".
At sea. It may be used by fishing vessels to mean: "My
nets have come fast
upon an obstruction".
Q——我船没有染疫，请发给进口检疫证；
* My vessel is "healthy" and I request free pratique."
S—我船正在使用倒车;
* | am operating astern propulsion.
T——请让清我船，正在进行双网拖作业;
* Keep clear of me: I am engaged in pair trawling.
U——你船正进入危险之中；
* You are running into danger.
V——我船需要救助;
* I require assistance.
W——我船需要医护救助;
*I require medical assistance
X——停止你的执行意图，注意我的信号;
* Stop carrying out your intentions and watch for my signals.
Y——我船正在拖锚;
* I am dragging my anchor.
Z——我船需要拖轮;
* I require a tug.
（2)双字母信号（two-letter signals)
双字母信号由两个英文字母构成，表达一个完整的意义，属于规则的通用部分。全部信号码分为九个部分：
第一部分：遇险-紧急（AC-HT)
I Distress-emergency
第二部分：伤亡事故-损坏（HV-LJ)
II Casulties-damages
第三部分：助航设备-航行-水文（LK-QC)
II Aids to navigation-navigation-hydrography
第四部分：船舶操纵（QD-SQ)
IV Manoeuvres
第五部分：杂项（ST-VF)
V Miscellaneous
第六部分：气象-天气（VG-YD)
VI Meteorology-weather
第七部分：船舶定线（YG)
VII Routing of ship
第八部分：通信（YH-ZR)
Communications
第九部分：国际健康检疫规则（ZS-ZZ)
IX International Health Regulations
（3)三字母信号（three-letter signals)
三字母信号码由以字母M(medical)为首的三个英文字母组成，从MAA-MVU按字母顺序排列，专供进行医疗方面通信时使用。例如：
MAA= I request urgent medical advice.
MQB=I can not understand your signal;please
usestandard method of case description.
MRI=You should refer to your international Ship's
Medical Guide if available or its equivalent.
MUC=Give water only in small quantities.
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