The IMO Standard Marine Communication Phrases (SMCP) has been compiled: 

- to assist in the greater safety of navigation and of the conduct of the ship, 

- to standardize the language used in communication for navigation at sea, in port approaches, waterways and harbours, and on-board vessels with multilingual crews, and 

- to assist maritime training institutions in meeting the objectives mentioned above. 

These phrases are not intended to supplant or contradict the International Regulations for Preventing Collisions at Sea, 1972 or special local rules or recommendations made by IMO concerning ships' routing, neither are they intended to supersede the International Code of Signals, and their use in ship's external communications has to be in strict compliance with the relevant radiotelephone procedures as set out in the ITU Radio Regulations. Furthermore, the IMO SMCP, as a collection of individual phrases, should not be regarded as any kind of technical manual providing operational instructions.

The IMO SMCP meets the requirements of the STCW Convention, 1978, as revised, and of the SOLAS Convention, 1974, as revised, regarding verbal communications; moreover, the phrases cover the relevant communication safety aspects laid down in these Conventions. 

Use of the IMO SMCP should be made as often as possible in preference to other wording of similar meaning; as a minimum requirement, users should adhere as closely as possible to them in relevant situations. In this way they are intended to become an acceptable safety language, using English for the verbal interchange of intelligence among individuals of all maritime nations on the many and varied occasions when precise meanings and translations are in doubt, as is increasingly evident under modern conditions at sea.

The IMO SMCP is divided into External Communication Phrases and On-board Communication Phrases as far as its application is concerned, and into Part A and Part B as to its status within the framework of STCW1978 as revised. 

Part A covers phrases applicable in external communications and may be regarded as the replacement of the Standard Marine Navigational Vocabulary 1985, which is required to be used and understood under the STCW Code, 1995, Table II/1. This part is enriched by essential phrases concerning ship handling and safety of navigation to be used in on-board communications, particularly when the Pilot is on the bridge, as required by Regulation 14(4), Chapter V, SOLAS 1974, as revised. 

Part B calls attention to other on-board standard safety-related phrases which, supplementary to Part A may also be regarded as useful for maritime English instruction.

The IMO SMCP is not intended to provide a comprehensive maritime English syllabus, which is expected to cover a far wider range of language skills to be achieved in the fields of vocabulary, grammar, discourse abilities, etc., than the IMO SMCP could ever manage. However, Part A in particular should be an indispensable part of any curriculum which is designed to meet the corresponding requirements of the STCW Convention 1978 as revised. In addition, Part B offers a rich choice of situations covered by phrases well suited to meet the communication requirements of the STCW Convention 1978 as revised, which mariners are implicitly expected to satisfy. 

The IMO SMCP should be taught and learned selectively according to users' specific needs, rather than in its entirety. The respective instruction should be based on practice in the maritime environment, and should be implemented through appropriate modern language teaching methods.

The IMO SMCP builds on a basic knowledge of the English language. It was drafted intentionally in a simplified version of maritime English in order to reduce grammatical, lexical and idiomatic varieties to a tolerable minimum, using standardized structures for the sake of its function aspects, i.e. reducing misunderstanding in safety-related verbal communications, thereby endeavoring to reflect present maritime English language usage on board vessels and in ship-to- shore/ship-to- ship communications. 

This means that in phrases offered for use in emergency and other situations developing under considerable pressure of time or psychological stress, as well as in navigational warnings, a block language is applied which uses sparingly or omits the function words the, a/an, is/are, as done in seafaring practice. Users, however, may be flexible in this respect.

Further communicative features may be summarized as follows: 

- avoiding synonyms 

- avoiding contracted forms 

- providing fully worded answers to "yes/no"-questions and basic alternative answers to sentence questions 

- providing one phrase for one event, and 

- structuring the corresponding phrases according to the principle: 

identical invariable plus variable.

( ) brackets indicate that the part of the message enclosed within the brackets may be added where relevant; 

/ oblique strokes indicate that the items on either side of the stroke are alternatives; 

… dots indicate that the relevant information is to be filled in where the dots occur; 

(italic letters) indicate the kind of information requested; 

~ tildes precede possible words or phrases which can be used after/in association with the given standard phrase.

When it is necessary to indicate that the IMO SMCP are to be used, the following message may be sent:

"Please use IMO Standard Marine Communication Phrases."

"I will use IMO Standard Marine Communication Phrases."

2.1 Spelling of letters

When spelling is necessary, only the following spelling table should be used:

In shore-to-ship and ship-to-shore communication or radio communication in general, the following eight Message Markers may be used (also see "Application of Message Markers" given in PART A1/6 "Vessel Traffic Service (VTS) Standard Phrases"):

(i) Instruction

(ii) Advice

(iii) Warning

(iv) Information

(v) Question

(vi) Answer

(vii) Request

(viii) Intention

4.1 When the answer to a question is in the affirmative, say:

"Yes .... " followed by the appropriate phrase in full.

4.2 When the answer to a question is in the negative, say:

"No ..." followed by the appropriate phrase in full.

4.3 When the information requested is not immediately available, say:

"Stand by" followed by the time interval within which the information will be available.

4.4 When the information requested cannot be obtained, say:

"No information."

4.5 When an INSTRUCTION (e.g. by a VTS Station, naval vessel or other fully authorized personnel ) or an ADVICE is given, respond if in the affirmative:

"I will/can… " - followed by the instruction or advice in full; and,

if in the negative, respond:

"I will not/cannot…" - followed by the instruction or advice in full. Example: "ADVICE. Do not overtake the vessel North of you."

Respond: "I will not overtake the vessel North of me."

4.6 Responses to orders and answers to questions of special importance both in external and on-board communication are given in wording in the phrases concerned.

5.1 MAYDAY to be used to announce a distress message

5.2 PAN PAN to be used to announce an urgency message

5.3 SECURITE to be used to announce a safety message

6.1 "How do you read (me)?"

6.1.1 "I read you ...

bad/one with signal strength one (i.e. barely perceptible) 

poor/two with signal strength two (i.e. weak)

fair/three with signal strength three (i.e. fairly good) 

good/four with signal strength four (i.e. good) 

excellent/five with signal strength five (i.e. very good)

6.2 When it is advisable to remain on a VHF Channel / frequency, say:

"Stand by on VHF Channel ... / frequency ... ."

6.2.1 When it is accepted to remain on the VHF channel / frequency indicated, say: 

"Standing by on VHF Channel ... / frequency ... . "

6.3 When it is advisable to change to another VHF Channel / frequency, say: 

"Advise (you) change to VHF Channel ... / frequency ... ."

"Advise (you) try VHF Channel ... / frequency... ."

6.3.1 When the changing of a VHF Channel / frequency is accepted, say:

 "Changing to VHF Channel ... / frequency ... ."

When a mistake is made in a message, say:

"Mistake ..." followed by the word:

"Correction ... " plus the corrected part of the message. 

Example: "My present speed is 14 knots - mistake.'

Correction my present speed is 12,one-two, knots."

"I am/I am not ready to receive your message."

9.1 If any parts of the message are considered sufficiently important to need safeguarding, say:

"Repeat ... " - followed by the corresponding part of the message. 

Example: "My draft is 12.6 repeat one-two decimal 6 meters."

"Do not overtake - repeat - do not overtake."

9.2 When a message is not properly heard, say:

"Say again (please)."

Numbers are to be spoken in separate digits: 

"One-five-zero" for 150

"Two decimal five or

Two point five" for 2.5

Note: Attention!When rudder angles, e.g. in wheel orders, are given, say:

"Fifteen" for 15 or

"Twenty" for 20 etc.

11.1 When latitude and longitude are used, these shall be expressed in degrees and minutes (and decimals of a minute if necessary), North or South of the Equator and East or West of Greenwich.

Example: "WARNING. Dangerous wreck in position 15 degrees 34 minutes North

061 degrees 29 minutes West."

11.2 When the position is related to a mark, the mark shall be a well-defined charted object.

The bearing shall be in the 360 degrees notation from true north and shall be that of the position FROM the mark.

Example: "Your position bearing 137 degrees from Big Head lighthouse distance 2.4 nautical miles."

The bearing of the mark or vessel concerned is the bearing in the 360 degree notation fromnorth (true north unless otherwise stated), except in the case of relative bearings.

Bearings may be either FROM the mark or FROM the vessel.

Examples: "Pilot boat is bearing 215 degrees from you."

Note: Vessels reporting their position should always quote their bearing FROM themark, as described in paragraph 11.2 of this section.

12.1 Relative bearings

Relative bearings can be expressed in degrees relative to the vessel's head. More frequently this is in relation to the port or starboard bow.

Example: "Buoy 030 degrees on your port bow."

(Relative D/F bearings are more commonly expressed in the 360 degree notation.)

Always to be expressed in 360 degree notation fromnorth (true north unless otherwise stated). Whether this is to TO or FROM a mark can be stated.

Relative bearings can be expressed in degrees relative to the vessel's head. More frequently this is in relation to the port or starboard bow.

Example: "Buoy 030 degrees on your port bow."

(Relative D/F bearings are more commonly expressed in the 360 degree notation.)

To be expressed in nauticalmiles or cables (tenths of amile), the unit always to be stated.

To be expressed in knots:

15.1 without further notation, meaning speed through the water; or,

15.2.1.1 "ground speed", meaning speed over the ground.

Times should be expressed in the 24 hour UTC notation; if local time will be used in ports or harbours it should clearly be stated.

Place names used should be those on the chart or in SailingDirections in use. Should these not be understood, latitude and longitude should be given.

Some words in English have meanings depending on the context in which they appear. Misunderstandings frequently occur, especially in VTS communications, and have produced accidents. Such words are:

18.1 The conditionals "may", "might", "should" and "could"

May

Do not say: "May I enter the fairway?"

Say: "QUESTION. Do I have permission to enter the fairway?"

Do not say: "You may enter the fairway."

Say: "ANSWER. You have permission to enter the fairway." 

Might

Do not say: "I might enter the fairway."

Say: "INTENTION. I will enter the fairway. " 

Should

Do not say: "You should anchor in anchorage B 3." 

Say: "ADVICE. Anchor in anchorage B 3."

Could

Do not say: "You could be running into danger."

Say: "WARNING. You are running into danger."

18.2 The word "can"

The word "can" describes either the possibility or the capability of doing something. In the IMO SMCP the situations where phrases using the word "can" appear make it clear whether a possibility is referred to .In an ambiguous context, however, say, for example:

"QUESTION. Do I have permission to use the shallow draft fairway at this time?"

Do not say: "Can I use the shallow draft fairway at this time?" if you are asking for a permission.

(The same applies to the word "May")