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What is Chain Register?


Safety is the main criterion on board ship, then let it be the safety of the crew onboard or the safety of the equipment. To make sure that the equipment onboard a ship is being taken care of a record of tests and examinations to be kept on board. For safekeeping of lifting appliances, a chain register is to be carried onboard.

“A register of the lifting appliances and items of loose gear shall be kept in form prescribed by the competent authority, account being taken of the model recommended by the International Labour Office.”

A Chain Register Register is to be standard international form as recommended by the International Labour Office in accordance with the ILO Convention No. 152. Chain Register to be maintained up to date as per the requirement of the Dock Safety Regulation and endorsed and signed by a competent person as required. It contains a certificate of tests and registers all reports of examination of load-bearing machinery, chains and wire ropes before they are put in use.

Contents of Chain Register

A Chain Register is divided in three parts:

Entries to be made:

  • Situation and description of lifting appliances and loose gear (with distinguishing number or marks, if any) which have been thoroughly examined
    (If all the lifting appliances are thoroughly examined on the same date it will be sufficient to enter in here “All lifting appliances and loose gear”. If not, the parts which have been thoroughly examined on the dates stated must be clearly indicated.)
  • Certificate Numbers of the Gears
  • Examination Performed
    The thorough examinations to be indicated in this part including:
    • Initial
    • 12 monthly
    • Five yearly
    • Repair/damage
    • Other thorough examinations including those associated with heat treatment.
  • Remarks, if any (To be dated and signed)
  • Date and Signature

Part 2 – Regular Examination of Loose Gear

Entries to be made:

  • Situation and description of loose gear (with distinguishing number or mark, if any) which has been inspected
    (All loose gear should be inspected before use. However, entries need only be made when the inspection discloses a defect.)
  • Signature and date of the responsible person carrying out the inspection
  • Remarks (To be dated and signed)

Part 3- Annealing of chains, rings, hooks, shackles and swivels (other than those that are exempted)

Some loose gears are exempted, which are as follows:

  • Chain made of cast iron
  • Plate link chain
  • Chains, rings, hooks, shackles and swivels made of steel
  • Pulley blocks
  • Hooks and swivels having screw-threaded parts or ball bearings
  • The tests, examinations, and inspections indicated in this Register are based on the requirements of the ILO Convention No. 152 and Recommendation No. 160.
  • These recommendations are intended to ensure that ships’ lifting appliances are initially certified by a competent person and to establish periodically that they continue to be in safe working order to the satisfaction of a competent person acceptable to the competent authority.
  • A Register of Lifting appliances and items of loose gear shall be kept in a form prescribed by the competent authority, account being taken of this model recommended by the International Labour Office. 
  • This Register and related Certificates shall be kept and be available to any person authorized by the competent authority. 
  • The Register and Certificates for gear currently aboard the ship shall be preserved for at least five years after the date of the last entry.

Initial Examination and Certification

  • Every lifting appliance shall be certified by a competent person before being taken into use for the first time to ensure that it is of good design and construction and of adequate strength for the purpose of which it is intended.
  • Before being taken into use for the first time a competent person shall supervise and witness testing, and shall thoroughly examine every lifting appliance.
  • Every item of loose gear shall, before being taken into use for the first time be tested, thoroughly examined and certified by a competent person in accordance with national law or regulations.
  • Upon satisfactory completion of the procedures indicated above the competent person shall complete and issue the Register of Lifting Appliances and attach the appropriate Certificates. An entry shall be made in Part I of the Register.
  • A rigging plan showing the arrangement of lifting appliances shall be provided. In the case of derricks and derrick cranes the rigging plan should show at least the following information:
    • the position of guys;
    • the resultant force on blocks, guys, wire ropes, and booms;
    • the position of blocks;
    • the identification mark of individual items;
    • arrangements and working range of union purchase.

Periodic Examinations and Re-testing

  • All lifting appliances and every item of loose gear shall be thoroughly examined by a competent person at least once every 12 months. The particulars of these thorough examinations shall be entered in Part I of the Chain Register.
  • Re-testing and thorough examination of all lifting appliances and every item of loose gear are to be carried out:
    • after any substantial alteration or renewal, or after repair of any stress-bearing part; and
    • in the case of lifting appliances at least once in every five years.
  • The re-testing referred above may be omitted provided the part which has been renewed or repaired is subjected by separate test, to the same stress as would have been imposed on to it if it had been tested in situation during testing of the lifting appliance.
  • The thorough examinations and tests referred to in Point 2 are to be entered in Part I of the Register.
  • No new item of loose gear shall be manufactured of wrought iron. Heat treatment of any existing wrought iron components should be carried out to the satisfaction of the competent person. No heat treatment should be applied to any item of loose gear unless the treatment is in accordance with the manufacturer’s instruction; to the satisfaction of the competent person. Any heat treatment and the associated examination are to be recorded by the competent person in Part I of the Register.

Regular visual inspections of every item of loose gear shall be carried out by a responsible person before use. A record of these regular inspections is to be entered in Part II of the Register, but entries need only be made when the inspection has indicated a defect in the item.


The certification forms to be used in conjunction with this Register (Form No. 1) are as follows:

Form No. 2 – Certificate of test and thorough examination of lifting appliances

Form No. 2 – Certificate of test and thorough examination of lifting appliances- Chain Register
Form No. 2 – Certificate of test and thorough examination of lifting appliances

Form No. 2 (U) – Certificate of test and thorough examination of derricks used in union purchase

Form No. 2 (U) – Certificate of test and thorough examination of derricks used in union purchase
Certificate of test and thorough examination of derricks used in union purchase (Form No. 2 (U) )

Form No. 3 – Certificate of test and thorough examination of loose gear.

Form-3-Certificate of Test and Thorough Examination Of Loose Gear
Certificate of Test and Thorough Examination Of Loose Gear (Form-3)

Form No. 4 – Certificate of test and thorough examination of wire rope.

Form No. 4 – Certificate of test and thorough examination of wire rope
Certificate of test and thorough examination of wire rope (Form No. 4)

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List of Special Areas Under MARPOL


What are Special Areas?

As defined under the MARPOL Annexes I, IV and V, special areas are the sea areas where for recognised technical reasons in relation to its Oceanographic and Ecological and to the particular character of their sea traffic, the adoption of special mandatory methods for the prevention of pollution of the sea from ships by oil, sewage or garbage, as applicable, is required.
They are provided with higher level of protection than, any areas of the sea.

Special areas under MARPOL are as follows:

MARPOL Annex l: Oil


MARPOL Annex ll: Noxious Liquid Substances


MARPOL Annex III: Harmful Substances carried at Sea in Packaged Form

No Special Areas for MARPOL Annex III

MARPOL Annex lV: Sewage


MARPOL Annex V: Garbage

MARPOL Annex Vl: Air Pollution (Emission Control Areas)


The Special Area requirement for these area have not taken effect because of lack of notifications from MARPOL Parties whose coastlines border the relevant Special Areas on the existence of adequate reception facilities (Regulations 38.6 of MARPOL Annex l and 5(4) of MARPOL Annex V).

**  The new special area requirements, which entered into force on 1 January 2013, will only take effect upon receipt of sufficient notifications on the existence of adequate reception facilities from Parties to MARPOL Annex IV whose coastlines border the relevant special area (regulation 13.2 of the revised MARPOL Annex IV, which was adopted by Resolution MEPC.200(62) and which entered into force on 1 January 2013).
***  A ship constructed on or after 1 January 2016 and is operating in these emission control areas shall comply with NOx Tier III standards set forth in Regulation 13.5 of MARPOL Annex VI.
**** A ship constructed on or after 1 January 2021 and is operating in these emission control areas shall comply with NOX Tier III standards set forth in Regulation 13.5 of MARPOL Annex VI.

Download  the List of Special areas under MARPOL here

Brief Notes on Enhanced Survey Program (ESP)

ship-operation-ship-safety-environmental protection-marinerscircle

  • Enhanced Survey Programme Code is a guideline for shipping companies and their owners to prepare their ships for special surveys to maintain the safety of the ship while at Sea or at the Port.
  • The Enhanced Survey Programme Code was adopted under Resolution A.744(18) on 4 November 1993 and
  • Amended in Resolution MSC.261(84) adopted on 16 May 2008.

ESP Code consists of two annexes;

  • Annex A– Guidelines on Enhanced Survey Programme of Inspection during the Surveys of Bulk Carriers, Annex A further divided into two parts;
    • Part A: Bulk Carriers Having Single-Side Skin Construction
    • Part B: Bulk Carriers Having Double-Side Skin Construction
  • Annex B: Guidelines on Enhancing Survey Programme of inspection during a survey of Oil Tankers.

Annexes A and B consists of chapters:

Each Part A & B has 8 chapters which are almost similar. The only dissimilarities being operational and constructional aspects of both types of vessels i.e. Oil Tankers and Bulk Carriers

Annex A: Guidelines on the Enhanced Programme Of Inspections During Surveys of Bulk Carriers​

  1. General
  2. Enhanced Survey Carried Out During Periodical Survey
  3. Enhanced Survey Carried Out During Annual Survey
  4. Intermediate Enhanced Survey
  5. Preparations for Survey
  6. Documentation on Board
  7. Procedures for Thickness Measurements
  8. Reporting and Evaluation of Survey


  • Annex 1 Requirements for Close-Up Survey at Periodical Surveys
  • Annex 2 Requirements for Thickness Measurements at Periodical Surveys
  • Annex 3 Owner’s Inspection Report
  • Annex 4 Principles for Planning Document
  • Annex 5 Procedures for Certification of A Company Engaged In Thickness Measurements Of Hull Structures
  • Annex 6 Reporting Principles
  • Annex 7 Condition Evaluation Report
  • Annex 8 Recommended Procedures for Thickness Measurements
  • Appendix 1 General Particulars
  • Appendix 2 Reports on Thickness Measurement
  • Appendix 3 Guidance on Thickness Measurement

Annex B Guidelines on the Enhanced Programme Of Inspections During Surveys of Oil Tankers​

  1. General
  2. Enhanced Survey Carried Out During Periodical Survey 
  3. Enhanced Survey Carried Out During Annual Survey 
  4. Intermediate Enhanced Survey 
  5. Preparations for Survey 
  6. Documentation on Board 
  7. Procedures for Thickness Measurements
  8. Reporting and Evaluation of Survey 


  •  Annex 1 Requirements for close-up survey at periodical surveys
  • Annex 2 Requirements for thickness measurements at periodical surveys
  • Annex 3 Requirements for tank pressure testing at periodical surveys
  • Annex 4 Requirements for extent of thickness measurements at areas of substantial corrosion. Periodical survey within the cargo area,
  • Annex 5 Owner’s inspection report,
  • Annex 6 Principles for planning document,
  • Annex 7 Procedures for certification of a company engaged in thickness measurements of hull structures, 
  • Annex 8 Reporting principles, 
  • Annex 9 Condition evaluation report,
  • Annex 10 Recommended procedures for thickness measurements,
    • Appendix 1 General particulars,
    • Appendix 2 Reports on thickness measurement, 
    • Appendix 3 Guidance on thickness measurement

The ESP Code applies to:

  • The Guidelines should apply to all self-propelled bulk carriers of 500 GRT and above having single-side skin construction. Where a bulk carrier has a combination of single- and double-side skin construction, the relevant requirements of parts A and B should apply to that construction, as applicable surveys of hull structure and piping systems in way of cargo holds, cofferdams, pipe tunnels, void spaces, fuel oil tanks, within the cargo length area and all ballast tanks.
  • contains the minimum extent of examination, thickness measurements, and tank testing. The survey should be extended when substantial corrosion and/or structural defects are found and include additional close-up surveys when necessary.
  • ships subject to compliance with Regulation XII/6.1 of the Convention should be subject to the additional thickness measurement guidance contained in Annex 11.
  • Ships subject to compliance with resolution MSC.168(79) should be subject to the additional thickness measurement guidance contained in Annex 15.
  • For bulk carriers with hybrid cargo hold arrangements, e.g. with some cargo holds of single-side skin and others of double-side skin, the requirements of part B of annex A apply to cargo holds of double-side skin and associated wing spaces.
  • The surveys should be carried out during the surveys prescribed by Regulation I/10 of the 1974 SOLAS Convention, as amended.


  • The Guidelines should apply to surveys of hull structure and piping systems in way of cargo holds, cofferdams, pipe tunnels, void spaces within the cargo length area and all ballast tanks. The surveys should be carried out during the surveys prescribed by the 1974 SOLAS Convention, as amended.
  • The Guidelines should apply to surveys of hull structure and piping systems in way of cargo holds, cofferdams, pipe tunnels, void spaces within the cargo length area and all ballast tanks. The surveys should be carried out during the surveys prescribed by the 1974 SOLAS Convention, as amended.


  • Bulk carrier is a ship which is constructed generally with a single deck, top-side tanks, and hopper side tanks in cargo spaces and is intended primarily to carry dry cargo in bulk and includes such types as ore carriers and combination carriers
  • Representative spaces are those which are expected to reflect the condition of other spaces of similar type and service and with similar corrosion prevention systems. When selecting representative spaces account should be taken of the service and repair history on board and identifiable critical and/or suspect areas.
  • The close-up survey is a survey where the details of structural components are within the close visual inspection range of the surveyor, i.e. normally within reach of the hand
  • Suspect areas are locations showing substantial corrosion and/or are considered by the surveyor to be prone to rapid wastage.
  • Substantial corrosion is an extent of corrosion such that assessment of corrosion pattern indicates a wastage in excess of 75% of allowable margins but within acceptable limits
  • Coating condition is defined as follows:
    • GOOD- condition with only minor spot rusting;
    • FAIR- condition with a local breakdown of coating at edges of stiffeners and weld connections and/or light rusting over 20% or more of areas under consideration, but less than as defined for the POOR condition
    • POOR- condition with a general breakdown of coating over 20% or more of areas or hard scale at 10% or more of areas under consideration.
  • Critical structural areas are locations that have been identified from calculations to require monitoring or from the service history of the subject ship or from similar or sister ships to be sensitive to cracking, buckling or corrosion which would impair the structural integrity of the ship.


  • For bulk carriers of 20,000 tons deadweight and above, two surveyors should jointly carry out the first scheduled renewal survey after the bulk carrier passes 10 years of age (i.e. third renewal survey), and all subsequent renewal surveys and intermediate surveys.

Enhanced Survey Carried Out During Periodical Survey:

  • The enhanced survey may be commenced at the fourth annual survey and be progressed during the succeeding year with a view to completion by the fifth-anniversary date
  • The survey should include, in addition to the requirements of the annual survey, examination, tests and checks of sufficient extent to ensure that the hull and related piping is in a satisfactory condition and is fit for its intended purpose for the new period of validity of the Cargo Ship Safety Construction Certificate, subject to proper maintenance and operation and to periodical surveys being carried out.
  • All cargo holds ballast tanks, pipe tunnels, cofferdams and void spaces bounding cargo holds, decks and outer hull should be examined, and this examination should be supplemented by thickness measurement and testing as deemed necessary, to ensure that the structural integrity remains effective. The examination should be sufficient to discover substantial corrosion, significant deformation, fractures, damages or other structural deterioration

Requirements for Close-Up Survey At Periodical Surveys

Requirements for Thickness Measurements at Renewal Surveys

List of Particular Sensitive Sea Areas (PSSAs)


What is Particular Sensitive Sea Areas (PSSAs)?

“Areas that need special protection through action by the IMO because of their significance for recongnized Ecological, Socio- economic or Scientific Attributes, where such attributes may be vulnerable to damage by international shipping activities.”

The criteria for the identification of particularly sensitive sea areas and the criteria for the designation of special areas are not mutually exclusive. In many cases a Particularly Sensitive Sea Area may be identified within a Special Area and vice versa.

Guidelines on designating a “Particularly Sensitive Sea Area” (PSSA) are contained in resolution A.982(24) Revised guidelines for the identification and designation of Particularly Sensitive Sea Areas (PSSAs).

List of PSSAs Adopted:

​The following PSSAs have been designated:

  • The Great Barrier Reef, Australia (designated a PSSA in 1990)
  • The Sabana-Camagüey Archipelago in Cuba (1997)
  • Malpelo Island, Colombia (2002)
  • The sea around the Florida Keys, United States (2002) 
  • The Wadden Sea, Denmark, Germany, Netherlands (2002)
  • Paracas National Reserve, Peru (2003)
  • Western European Waters (2004)
  • Extension of the existing Great Barrier Reef PSSA to include the Torres Strait (proposed by Australia and Papua New Guinea) (2005)
  • Canary Islands, Spain (2005)
  • The Galapagos Archipelago, Ecuador (2005)
  • The Baltic Sea area, Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland and Sweden (2005)
  • The Papahānaumokuākea Marine National Monument, United States (2007)
  • The Strait of Bonifacio, France and Italy (2011)
  • The Saba Bank, in the North-eastern Caribbean area of the Kingdom of the Netherlands (2012)
  • Extension of Great Barrier Reef and Torres Strait to encompass the south-west part of the Coral Sea (2015)
  • The Jomard Entrance, Papua New Guinea (2016)
  • Tubbataha Reefs Natural Park, the Sulu Sea, Philippines (2017)

How PSSAs help protect the oceans

GPS (Global Positioning System)- Definition, Requirement, Principle, Working, Errors Explained



  • GPS is a satellite navigational system, funded and controlled by the US Department of Defence.
  • GPS is a ground based satellite navigational system that provides location and time information in all weather condition and anywhere on the Earth.
  • It was made by the US Government for their military use and later on it was provided to civilians also. It is a free service for everyone with a GPS Receiver.
  • GPS is backbone for modernising the global air and marine traffic system


  • Chp V/ Reg of SOLAS Code, requires all ships irrespective of size to have a receiver for a global navigation satellite system or a terrestrial radio navigation system, or other means, suitable for use at all times throughout the intended voyage to establish and update the ship’s position by automatic means.
  • Global Positioning Satellite System (GPSS) equipments installed on ships to fulfil above SOLAS regulation includes following categories of equipments:
    • Global positioning system (GPS) equipment.
    • Global navigational satellite system (GLONASS) equipment.
    • Differential global position system (DGPS) equipment.
    • Differential global navigation satellite system (DGLONASS) equipment and
    • Combined global position system and global navigation satellite system (GPS/GLONASS) receiver equipment.

Segments of GPS

  • Space Segment;
  • Control Segment or Ground Segment;
  • User Segment

Space Segment

  • It consists of total 24 satellites fixed evenly in SIX orbits. Which means each orbit has FOUR Satellites.
  • Each of these satellites are placed at 60° apart from each other in each orbit.
  • Each orbit is inclined at 55° to the equinoctial. Each Satellite moves at a speed of 3.9 km/sec at a height of 22000 km above Earth Surface.
  • Each satellite makes TWO complete orbits each day, repeating the same ground track each day.
  • At least FIVE Satellites are available for the user at any given time.

Control Segment (Ground Segment/ Control Station)

  • The Control Segment of GPS consists of a global network of ground facilities that track the GPS Satellite, monitor their transmission, performance analysis and send commands and data to the constellation.
  • Control Segment of the GPS consists of:
    • A master control station;
    • An alternative master control station;
    • 16 dedicated Ground based Monitoring stations (6 from Air Force and 10 from NGA);
    • 12 Ground Antennas as Upload Station
GPS Ground Segment Flow Diagran
How Control or Ground Segment works
  • The monitoring stations track the satellite.
  • Obtain data from the satellite and pass that information to Master Control Station.
  • The Master Control Station predict the future path and position of all the satellites.
  • The updated data is fed to the Upload Station which then transmit the same data to each satellite three times a day.
  • The Master Control Station can selectively degrade the satellite data. This degradation is known as Selective Availability, and it can cause position error of up-to 100 meters.

User Segment

  • User Segments are end users like Ships, Air crafts, our mobile phones, cars
  • User Segment consists of:
    • A Receiving Antenna;
    • A Receiver with built-in Computer;
    • A Display Unit
How User Segment works
  • The Receiver locks on the satellite, and from this satellite is obtained the almanac (the time) of all the other satellites and therefor selects the FOUR most suitable satellite for position fixing.
  • The final fix obtained is displayed on the display unit along with the other information like, SOG, COG, UTC, etc.
  • Each Satellite transmit a Navigational message of 30 secs duration using 50 bits/ sec data frame.

Navigational Message

  • Each Satellite transmit a Navigational message of 30 secs duration using 50 bits/ sec data frame.
  • This data which is different for each satellite and is previously supplied to the satellite by Master Control Station and is divided into FIVE Sub-frames
  • The First Sub-frame: contains the data related to satellite clock correction
  • The Second and Third Sub-frame: contains the satellite ephemeris data, which defines the position of the satellite. Ephermeris is a table or data file giving the calculated position of a celestial object at regular interval throughout a period.
  • The Fourth Sub-frame: It is an open gate and passes alphanumeric data to the user and one will be used of Upload Station has a need to pass some specific message or important message.
  • The Fifth Sub-frame: It gives the almanac of all the other satellites which include data on satellite health and identify codes thus allowing the user for optimum choice or the best choice of the satellite for the position fixing.

Position Fixing OR How GPS works?

  • It works on the principle of timing and ranging of satellite
  • The signal transmitted by the satellite travel at a speed of light (3 X 108 m/sec).
  • The receiver locks on to one satellite and, from this satellite it obtain almanac of all other satellites and thereby select the four most suitable satellites for position fixing .
  • By noting the time taken by signal to travel, is measured and distance of satellite from the receiver is calculated.
  • This way each Satellite gives a position sphere which after on intersection on the Earth surface gives position circle. Two of such circles gives 2D, but three, gives a 3D fix.
  • An additional fourth satellite re-assessment is taken by the GPS receiver to account for receiver clock bias and thus correct all satellite “Pseudo Ranges” to True Ranges and make the position free of error.
Speed DIstance Time Formula


Each satellite provides two types of codes:

  • P- Code or Precision Code: P-Code is only available for US Military and allies. The accuracy of this code is approx. 10 m.
  • C/A Code or Coarse Acquisition Code: available for all civilian receivers. the accuracy fir this code is approx 100 m


  • L1 Signals = 1575.42 MHz, consists of both C/A and P Codes
  • L2 Signals = 1227.6 MHz, consists of only P-Code

C/A Code

  • C/A Code is different for every satellite;
  • The C/A Code is made up of a sequence called chips;
  • This sequence repeats itself every milliseconds;
  • The C/A Code is for civilians.


  • The full code length is 267 days;
  • The P-Code is different for each satellite;
  • Due to the extreme long code length, it is difficult to lock on the P-Code;
  • The P-Code is available only for US and allies.

Pseudo Random Code (PRC)

  • Due to the fact that all the satellite works on same frequencies and each circuit has a unique code so all the satellite can use the same frequency with jamming into each other
  • The PRC is a fundamental part of GPS and has a very complicated digital code in other words complicated sequence of “on” and “off” pulses;
  • The signal is so complicated that it almost looks like a random electrical noise has named Pseudo-random

Function of these codes

  • For Satellite identification, since each satellite has a unique code;
  • For the measurement of propagation time, from satellite to the user.
Pseudo Random Code (PRC)

Errors of GPS

Clock Errors

a. Satellite Clock Error

  • this is caused due to the error between satellite clock and GPS time. Going to extremely high velocity in space that is 3.9 kilometre per second an error can creep in or move on in automatic clock on satellite.
  • This error is monitored by ground based segment and any error in the satellite clock forms part of the 30 sec navigational message sent by MCS.
  • Clock error can be caused positional area of about 1.5 metres.

b. User Clock Error

  • All the (space vessel) satellites are fitted with automatic clocks. It is not possible to install automatic locks on board the receiver because of high cost and huge size of the clock and if the user clock is not well synchronised with the satellite clock the range measurement will not be accurate and hence called Pseudo Ranges
  • This problem can be solved by using a reassurement satellite that is a fourth satellite.
  • 3 Satellites for 2-D Fix and 4 Satellites for 3-D Fix
  • True Ranges – Pseudo Ranges +/- Clock Error Range

Ionospheric and Tropospheric Delay or Errors

The radio waves transmitted by the satellite passes through different layers of atmosphere. this results into the change into the velocity of waves and hence affect the time and range measurement and fix obtained will not be accurate.

GDOP (Geometric Dilution of Precision)

  • The geometry of the position of satellite determines the angle of cut, which will affect the quality of the position obtained.
  • Wider the range of separation between satellites better the position obtained, and the lower the value of GDOP higher the accuracy of position.
  • The value of GDP is always indicated on GPS display.

Multi-path Error

  • This is caused by the satellite signal coming to receiver after being reflected from other obstructions, in addition to reach the receiver directly.
  • Two signals are those received simultaneously causes distortion of signal and in term affect the range measurement.
  • This problem is resolved by suitable siting of Antennas.


Deviation of satellite from predicate path

The satellites are monitored by ground segment and their paths are prdicted, but some of satellites may drift from the protective path, results into small position in accuracy.



Types of Position service in GPS

Precision Positioning Services (PPS)

  • Authorised user has access to PPS
  • Uses the P Codes
  • PPS predictable accuracy is 30 metres

Standard positioning services (SPS )

  • Civil users worldwide uses the SPS
    Uses C/A codes
  • Predicted accuracy of SPS is 35 metres
  • SPS is subject to selective availability, International down graduation of accuracy
  • Now it has been announced by the US Government that the international graduation of accuracy cannot be done.

MMD Mumbai | 2 MFG Oral Questions | 08 Aug 2019

Second Mate Oral Exam Questions
  • Venue: DG Shipping
  • External Surveyor: N/A
  • Internal Surveyor: Capt Das

Function II

  • What do you understand by corrugated bulkheads with diagram
  • Explain the procedure for preparations  of the hold before loading
  • What is a strum box in bilge?
  • What are the Brackets?
  • What areas to be checked for cracks in the hold?
  • IMDG contents and class
  • How to use the IMDG Code?
  • What is the information given in IMDG supplement
  • And many more questions related to IMDG Code and classes, more practical questions and many more but I forgot a few

Function III

  • What is IMO?
  • Marpol Annexes
  • Certificates in Annex I
  • Why MARPOL came in force and why 73/78,
  • Lifeboat basics, 
  • Immersion Suits and TPA,
  • Fire in the galley. Action.
  • 2 MFG Oral
  • Fire blanket material,
  • Frame numbering, 
  • Explain your ship from forward to aft, and many more but practical questions

External asked MARPOL in detail with explanation of:

Code of Intact Stability | Intact Stability Criteria for All Ships (Must know for 2MFG Exam)


General intact stability criteria for all ships:

The Code for Intact Stability was adopted on 4 November 1993 under IMO Resolution A.749(18). This Intact Stability Code was provided to seafarers to give recommendations related to Intact Stability criteria and other measures for ensuring the safe operations of the ship to minimize risk to ships, the personnel, and the environment. Recommendations mentioned in this code can be found in various codes of IMO, such as the MODU Code or DSC Code.

The Code for Intact Stability applies to:

  • Cargo ships
  • Cargo ships carrying timber cargo
  • Cargo ships carrying grains in bulk
  • Passenger ships
  • Fishing vessels
  • Special purpose vessels (SPVs) (mechanically self-propelled ships, which carries more than 12 personnel on-board)*
  • Mobile Offshore Drilling Vessels (MODU)
  • Pontoons
  • Dynamically Supported Crafts (DSC)
  • Container Ships

Stability Booklet:

  • Stability Booklet gives stability data and plans associated with ships arrangement. The plans should be written in the ship’s official language and the language of the master. If the languages used are neither English nor French then the text should include a translation into one of these languages.
  • Each Ship should be provided with a stability booklet, approved by administrating Flag Society. The Stability Booklet should contain sufficient information which should enable the master to operate the ship in the compliance of this Code.
  • On mobile drilling units, the stability booklet is called Operating Manual
  • the format and the information included may vary depending on the ship’s type and its operation. However, a stability booklet should contain:
    • A general description of the ship;
    • a table of content and index for each booklet;
    • Instruction on use of the booklet;
    • General Arrangement Plans showing watertight compartments, closures, vents, down flooding angles, permanent ballast, allowable deck loading, and freeboard diagrams;
    • Hydrostatic Curves or Tables and Cross Curves of stability calculated on the free-trimming basis, for the ranges of displacement and trims anticipated in normal operating conditions;
    • Tables showing capacities and center of gravity for each cargo stowage space (Capacity Plan);
    • Tables showing capacities, the center of gravity and free surface data of each tank (Tank Sounding Tables);
    • information on loading instructions, such as maximum KG and Minimum GM curve or table which can be used to determine compliance with applicable stability criteria;
    • Standard operating conditions and examples for developing other acceptable loading conditions using the information contained in the stability booklet;
    • a brief description of the stability calculations done, including assumptions;
    • general instructions for preventing unintentional flooding;
    • information concerning the use of any special cross-flooding fittings, with a description of damage conditions which may require cross-flooding;
    • any other necessary guidance for the safe operation of the ship under normal and emergency conditions;
    • inclining test report for the ship; or
      • where the stability data are based on the sister ship, the inclining test report of that sister ship along with the light-ship measurement report for the ship in question, or;
      • where lightship particulars are determined by the other methods than from inclining of the ship or its sister, a summary of methods used to determine those particulars;
  • As an alternative to the stability booklet, a simplified booklet in an approved form containing sufficient information to operate the ship in compliance with the applicable provisions of the Code of Intact Stability may be provided at the discretion of the authority concerned.
  • As a supplement to the approved Stability Booklet, a loading computer may be used to facilitate the stability calculations, including assumptions (loadicator);
    • the input/output form in the computer and the screen representation desired to be similar to the one in the stability booklet so that the operators will be easily familiarized with stability booklet.
    • the language of the manual for the computer to use should be simple and straightforward, written as per sound marine practice and in a language common to all officers on board, and should be provided with the loading computer.
  • In order to validate the proper functioning of the loading computer program, four loading conditions taken from the final stability booklet should run in the computer periodically and the print-outs should be maintained on-board as check conditions for future reference.
  • For Special Purpose Ships, Dynamically Supported Crafts, and Novel Crafts should be provided with additional information in the stability booklet, such as design, limitations, maximum speed, worst intended weather conditions or other information, regarding the handling of the craft that the master needs to handle the ship safely.

General Precautions against capsizing:

  • Along with the compliance with the code of intact stability, the master will have to exercise good seamanship in order to ensure the immunity against capsizing. Attention should be paid to the season of the year, weather forecasts, and navigational zones.
  • Make sure that the cargo being carried out on the ship, is within the stowing limits of the ship so that the compliance with the criteria can be achieved.
  • Before voyage commences make sure that all cargo and sizable pieces of equipment are properly lashed and stowed to minimize the lateral and longitudinal shifting, while at sea, under the effect of acceleration caused by rolling and pitching.
  • The number of partially filled or slack tanks to be kept to a minimum because of their adverse effect on stability.
  • If a ship is engaged in towing operations, it should not carry a deck cargo, except if it is of limited amount, properly secured, so that it would not endanger the safe working of the crew on the deck or impede the proper functioning of the towing equipment.
  • Attention to be paid to the possible adverse effect on stability where certain cargoes are carried. In this connection attention to be paid to the Code of Safe Practices for Solid Bulk Cargoes.
  • The stability criteria mentioned in this code of intact stability gives minimum values, not maximum values. Special attention should be paid to values of metacentric height, as excessive values of the same may lead to acceleration forces which could put the ship in danger.
  • Fixed ballast, if used should be installed under the supervision of Administration and in a manner that prevents shifting of position. Fixed ballast should neither be removed from ship nor relocated within ship without the approval of Administration.

Operational Procedures related to Weather Conditions:

  • All the doorways and other openings through which water may enter into the hull or deck-house, forecastle, etc., should be properly closed in adverse weather conditions.
  • Weather-tight and water-tight hatches, doors, etc., should be kept closed during navigation, except when necessarily opened for the working of the ship, and should always be ready for immediate closure and be marked to indicate that these fittings are to be kept closed except for the access.
  • In fishing vessels, hatch covers and flush deck scuttles should be kept properly secured when not in use during fishing operations. All portable deadlights should be maintained in good condition and securely closed in bad weather.
  • Any closing devices provided for vent pipes to fuel tanks should be secured in bad weather.
  • Over-relying on automatic steering may be dangerous as this prevents ready changes to course which may be needed in bad weather.
  • In all conditions of loading necessary care should be taken to maintain a seaworthy freeboard
  • In severe weather, the speed of the ship should be reduced if excessive rolling, propeller emergency, shipping of water on deck or heavy slamming occurs. Six heavy slammings or 25 propeller emergences during 100 pitching motions should be considered dangerous.
  • Special attention should be paid when a ship is sailing in following or quartering seas because dangerous phenomena such as parametric resonance, broaching to, reduction of stability on the wave crest, and excessive rolling may occur singularly, in sequence or simultaneously in multiple combinations, creating a threat of capsizing.
  • Particularly dangerous is the situation when the wavelength is of the order of 1.0 – 1.5 times ship’s length. A ship’s speed and/or course should be altered appropriately to avoid the above-mentioned phenomena.
  • Water trapping in deck wells should be avoided. If freeing ports are not sufficient for the drainage of the well, the speed of the ship should be reduced or course changed, or both. Freeing ports provided with closing appliances should always be capable of functioning and are not to be locked.
  • Masters should be aware that steep or breaking waves may occur in certain areas, or in certain wind and current combinations (river estuaries, shallow water areas, funnel-shaped bays, etc.). These waves are particularly dangerous, especially for small ships.
  • Dynamically supported craft should not be intentionally operated outside the worst intended conditions and limitations specified in the Dynamically Supported Craft Permit to Operate, in the Dynamically Supported Craft Construction and Equipment Certificate, or in documents referred to therein.
  • The use of operational guidelines for avoiding dangerous situations in severe weather conditions or an onboard computer-based system is recommended. The method should be simple to use.
  • Fish should never be carried in bulk without first being sure that the portable divisions in the holds are properly installed.

General intact stability criteria for all ships:

The following criteria are recommended for passenger and cargo ships:

  • The area under the righting lever curve (GZ Curve) should not be less than 0.055 meter-radians up to θ=30° angle of heel and not less than 0.09 meter-radians up to θ=40° or the angle of flooding θf* if this angle is less than 40°.
  • Additionally, the area under the righting lever curve (GZ curve) between the angles of the heel of 30° and 40° or between 30°and ef, if this angle is less than 40°, should not be less than 0.03 meter-radians.
  • The righting lever GZ should be at least 0.20 m at an angle of heel equal to or greater than 30°.
  • The maximum righting arm should occur at an angle of heel preferably exceeding 30° but not less than 25°.
  • The initial metacentric height GM0 should not be less than 0.15 m.
  • In addition, for passenger ships, the angle of heel on account of crowding of passengers to one side should not exceed 10°.
  • In addition for passenger ships, the angle of heel on account of turning should not exceed 10° when calculated using the following formula:
  • If anti-rolling devices are installed in a ship, the Administration should be satisfied that the above criteria can be maintained when the devices are in operation.
  • A number of influences such as beam wind on ships with large windage area, icing of topsides, water trapped on deck, rolling characteristics, following seas, etc., adversely affect stability and the Administrations are advised to take these into account, so far as is deemed necessary.

θf is the angle of heel at which openings in the hull superstructures or deckhouses which cannot be closed weathertight immerse. In applying this criterion, small openings through which progressive flooding cannot take place need not be considered as open.

Intact Stability Criteria for Tankers

Every oil tanker of 5,000 tonnes deadweight and above delivered on or after 1 February 2002, shall comply with the intact stability criteria of Annex I, Chp. 4/ Reg 27, as appropriate, for any operating draught under the worst possible conditions of cargo and ballast loading, consistent with good operational practice, including intermediate stages of liquid transfer operations. Under all conditions, the ballast tanks shall be assumed slack.

  • At the port, the initial metacentric height GMo, corrected for the free surface measured at 0° heel, shall be not less than 0.15 m;
  • At sea, the following criteria shall be applicable:
    • The area under the righting lever curve (GZ curve) shall be not less than 0.055 m·rad up to θ = 30° angle of heel and not less than 0.09 m·rad up to θ = 40° or another angle of flooding θf, if this angle is less than 40°. Additionally, the area under the righting lever curve (GZ curve) between the angles of the heel of 308 and 40° or between 30° and θf, if this angle is less than 40°, shall be not less than 0.03 m·rad;
    • The righting lever GZ shall be at least 0.20 m at an angle of heel equal to or greater than 30°;
    • The maximum righting arm shall occur at an angle of heel preferably exceeding 30° but not less than 25°; and
      d. The initial metacentric height GMo, corrected for free surface measured at 0° heel, shall be not less than 0.15 m.
  • The requirements of paragraph 1 of this regulation shall be met through design measures.

Intact Stability Criteria for Cargo ships carrying timber deck cargoes:

For ships loaded with timber deck cargoes and provided that the cargo extends longitudinally between superstructures (where there is no limiting superstructure at the after end, the timber deck cargo should extend at least to the after end of the aftermost hatchway) transversely for the full beam of ship after due allowance for a rounded gunwale not exceeding 4% of the breadth of the ship and/or securing the supporting uprights and which remains securely fixed at large angles of heel, the Administration may apply the following criteria which substitute the criteria for all ships:

  • The area under the righting lever curve (GZ curve) should not be less than 0.08 meter-radians up to 0 = 40° or the angle of flooding if this angle is less than 40°.
  • The maximum value of the righting lever (GZ) should be at least 0.25 m.
  • At all times during a voyage, the metacentric height GM0 should be positive after correction for the free surface effects of liquid in tanks and, where appropriate, the absorption of water by the deck cargo and/or ice accretion on the exposed surfaces.
  • Additionally, in the departure condition, the metacentric height should be not less than 0.10 m.

Stability booklet for Cargo ships carrying timber deck cargoes:

  • The ship should be supplied with comprehensive stability information which takes into account timber deck cargo. Such information should enable the master, rapidly and simply, to obtain accurate guidance as to the stability of the ship under varying conditions of service. Comprehensive rolling period tables or diagrams have proved to be very useful aids in verifying the actual stability conditions.
  • For ships carrying timber deck cargoes, the Administration may deem it necessary that the master is given information setting out the changes in deck cargo from that shown in the loading conditions when the permeability of the deck cargo is significantly different from 25% (see 4.1.6 below).
  • For ships carrying timber deck cargoes, conditions should be shown indicating the maximum permissible amount of deck cargo having regard to the lightest stowage rate likely to be met in service.

Operational measures for Cargo ships carrying timber deck cargoes:

  1. The stability of the ship at all times, including during the process of loading and unloading timber deck cargo, should be positive and to a standard acceptable to the Administration. It should be calculated
    having regard to:
    • the increased weight of the timber deck cargo due to:
      • absorption of water in dried or seasoned timber, and
      • ice accretion, if applicable;
    • variations in consumables;
    • the free surface effect of liquid in tanks; and
    • weight of water trapped in broken spaces within the timber deck cargo and especially logs.
  2. The master should:
    • cease all loading operations if a list develops for which there is no satisfactory explanation and it would be imprudent to continue loading;

Intact Stability Criteria for Containerships greater than 100 m

This section of the intact stability code applies to the container ships greater than 100 m. They may also be applied to other cargo ships with considerable flare or large water-plane areas. The Administration may apply the following criteria instead of intact stability criteria for general cargo ships.

  • The area under the righting lever curve (GZ curve) should not be less than 0.009/C meter-radians up to 0 = 30° angle of heel, and not less than 0.016/C meter-radians up to 0 = 40° or the angle of flooding ef (as defined above) if this angle is less than 40°.
  • Additionally, the area under the righting lever curve (GZ curve) between the angles of heel of 30° and 40° or between 30° and ef, if this angle is less than 40°, should not be less than 0.006/C meter-radians.
  • The righting lever GZ should be at least 0.033/C mat an angle of heel equal or greater than 30°.
  • The maximum righting lever GZ should be at least 0.042/C m.
  • The total area under the righting lever curve (GZ curve) up to the angle of flooding ef should not be less than 0.029/C meter-radians.
  • In the above criteria, the form factor C should be calculated using the formula and figures given below.

Standard conditions of loading to be examined

Loading Conditions:

The standard loading conditions referred to in the text of the present Code are as follows:

For a passenger ship:

  • ship in the fully loaded departure condition with full stores and fuel and with the full number of passengers with their luggage;
  • ship in the fully loaded arrival condition, with the full number of passengers and their luggage but with only 10% stores and fuel remaining;
  • ship without cargo, but with full stores and fuel and the full number of passengers and their luggage;
  • ship in the same condition as at .3 above with only 10% stores and fuel remaining.

For a cargo ship:

  • ship in the fully loaded departure condition, with cargo, homogeneously distributed throughout all cargo spaces and with full stores and fuel;
  • ship in the fully loaded arrival condition with cargo homogeneously distributed throughout all cargo spaces and with 10% stores and fuel remaining;
  • Ship in ballast in the departure condition, without cargo but with full stores and fuel;
  • ship in ballast in the arrival condition, without cargo and with 10% stores and fuel remaining.

For a cargo ship intended to carry deck cargoes:

  • ship in the fully loaded departure condition with cargo homogeneously distributed in the holds and with cargo specified in extension and weight on deck, with full stores and fuel;
  • ship in the fully loaded arrival condition with cargo homogeneously distributed in holds and with a cargo specified in extension and weight on deck, with 10% stores and fuel

Ballast Water Management


International Convention for the Control and Management of Ship's Ballast Water and Sediments
(Ballast Water Management Convention)

Image Credits: www.marasinews.com

Adoption: 13 February 2004
Entered into force: 08 Sept 2017


The Ballast Water Management Convention was adopted in 2004 to prevent the spread of harmful aquatic organisms from one region to another, by establishing standards and procedures for the management and control of ships’ ballast water and sediments.

Why Ballast Water Management?

Since the introduction of steel-hulled vessels, water has been used, instead of solid materials as ballast to stabilize vessels at sea. Ballast taken by any vessel contains a variety of organisms including bacteria and viruses and the adult and larval stages of the many aquatic and coastal plants and animals. While the vast majority of such organisms will not survive to the point when the ballast is discharged, some may survive and thrive in their new environment. These ‘non-native species’, if they become established, can have a serious ecological, economic and public health impact on the receiving environment.

The shipping industry has been identified as a major pathway for introducing species to new environments. This problem increased as trade and traffic volume expanded over the last few decades. While ballast water is essential for the stability of ship to ensure the safe and efficient modern shipping operations, the ballast itself may cause serious ecological, economic and health problems due to various marine species are carried in it.

The effects of the introduction of new species have in many areas of the world been devastating. Quantitative data show the rate of bio-invasions is continuing to increase at an alarming rate. As the volumes of seaborne trade continue overall to increase, the problem may not yet have reached its peak. The transfer of invasive marine species into new environments via ballast water has been identified as one of the major threats to the world’s oceans.

History of Ballast Water Management

  • In 1991, IMO adopted an MEPC Circular, Guidelines for Preventing the Introduction of Unwanted Organisms and Pathogens from Ship’s Ballast Waters and Sediment Discharges (Resolution MEPC.50(31)). These guidelines were updated in 1993.
  • While continuing its work towards the development of an international treaty, in 1997 IMO adopted Guidelines for Control and Management of Ships’ Ballast Water to Minimize the Transfer of Harmful Aquatic Organisms and Pathogens (Resolution A.868(20)).
  • After years of complex negotiations between the IMO Member States, International Convention for the Control and Management of Ships’ Ballast Water and Sediments also known as, the Ballast Water Management or BWM Convention was adopted on 13 February 2004 at IMO Headquarters in London.
  • This convention was adopted to regulate and control the discharge of the ship’s ballast water and reduce the risk of introducing non-native species from ships’ ballast water. To complement the BWM Convention, the IMO has adopted guidelines contained in its Marine Environmental Protection Committee (MEPC) resolutions and circulars.

Parties to the Convention are given the option to take additional measures that are subject to criteria set out in the Convention and to IMO guidelines. In response to that, other countries have introduced regulations in response to national concerns. 

The most influential of these is the United States Coast Guard (USCG) which has established both regulations and guidelines to prevent the introduction and spread of aquatic nuisance species. The USCG’s final rule was published on 23 March 2012 in the Federal Register and became effective on 21 June 2012.

Ballast Water Management Timeline
Image Credits: www.imo.org

Ballast Water Management Convention applies to:

The BWM Convention applies to all ships including submersibles, floating craft, floating platforms, FSUs and FPSOs.
It does not apply to:

  • ships not designed to carry ballast water
  • ships not operating in international waters
  • warships, naval auxiliary ships or other ships owned or operated by a state
  • ships only on non-commercial service, or
  • ships with permanent ballast water in sealed tanks.

The Convention requires all ships in international traffic are required to manage their ballast water and sediments to a certain standard, according to a ship-specific ballast water management plan. All ships will also have to carry a ballast water record book and an international ballast water management certificate. The ballast water management standards will be phased in over a period of time. As an intermediate solution, ships should exchange ballast water mid-ocean. However eventually, most ships installed an on-board ballast water treatment system.

From 8 September 2017 when Ballast Water Management came into force, all ships of 400 GRT and above having on board:

  • An approved Ballast Water Management plan
  • A Ballast Water Record Book.
  • All ships fitted with Ballast water treatment systems must have a type approval certificate in compliance with the IMO Guidelines for the approval of ballast water management systems (Resolution MEPC 174(58) (G8))
  • An International Ballast Water Management Certificate or statement of compliance.

The BWM Convention includes two performance standards for the discharge of ballast water: D1 and D2.

  • The D1 standard concerns ballast water exchange, which must be undertaken within open ocean areas, >200 nm from land and in seas >200 meters deep.
  • The D2 standard covers approved ballast water treatment systems.

Surveys and Certifications:

  • Ships below 400 GRT will be subject to national survey and certification regimes. The survey and certification scheme under the BWM Convention is similar to those of all other IMO conventions.
  • On completion of an initial survey, an International Ballast Water Management Certificate will be issued for a ship whose flag has ratified the BWM Convention; for other ships, a Ballast Water Management Certificate of Compliance will be issued. Both the Certificates and the Statement will be valid for five years subject to annual, intermediate and renewal surveys.
  • The IMO has published Interim Survey Guidelines (contained in the Circular, BWM.2/Circ.7) and it is expected that these will be incorporated into the IMO’s Harmonised System of Survey and Certification Guidelines (Resolution A.997(25)) once the BWM Convention enters into force.


  • An exemption may be granted to a ship or ships on a voyage or voyages between specified ports or locations, or to a ship that operates exclusively between specified ports or locations. Eg: A ferry trading solely between one or more ports.
  • Any exemption granted is valid for a maximum of five years subject to an intermediate review and provided the ship does not mix ballast water or sediments other than between the ports or locations specified in the exemption. However, it should be noted that the exemptions can be withdrawn at any time by the issuing administrations.
  • To be eligible for an exemption a risk assessment must be carried out in accordance with IMO Resolution MEPC.162(56) – Guidelines for Risk Assessment under Regulation A-4 of the BWM Convention. For further details on exemptions, you should contact the flag administration.

See other related posts, Function I

IMO Performance Standards for AIS


Chapter V/ Regulation 19/ 2.4.5 of SOLAS 73/78 states that:
“AIS shall,

  • provide automatically to appropriate equipped shore stations, other ships and aircraft information, including ship’s identity, type, position, course, speed, navigational status, and other safety-related information;
  • receive automatically such information from similarly fitted ships;
  • monitor and track ships; and
  • exchange data with shore-based facilities.”

In addition to these Resolution MSC.74(69) includes Recommendation on

IMO Performance Standards for AIS, which are:


    1. The AIS should improve the safety of navigation by assisting in the efficient navigation of ships, protection of the environment, and operation of Vessel Traffic Services (VTS), by satisfying the following functional requirements:
        • in a ship-to-ship mode for collision avoidance;
        • as a means for littoral States to obtain information about a ship and its cargo; and
        • as a VTS tool, i. e. ship-to-shore (traffic management).
    2. The AIS should be capable of providing ships and to competent authorities, information from the ship, automatically and with the required accuracy and frequency, to facilitate accurate tracking. Transmission of the data should be with the minimum involvement of ship’s personnel and with a high level of
    3. The installation of AIS should comply with the requirements of the Radio Regulations, applicable ITU-R Recommendations and General Requirements for Shipborne Radio Equipment Forming Part of The Global Maritime Distress And Safety System (GMDSS) And For Electronic Navigational Aids Resolution A.694 (17) 


  • The system should be capable of operating in a number of modes:

      • an “autonomous and continuous” mode for operation in all areas. This mode should be capable of being switched to/from one of the following alternative modes by a competent authority;
      • an “assigned” mode for operation in an area subject to a competent authority responsible for traffic monitoring such that the data transmission interval and/or time slots may be set remotely by that authority,
      • a “polling” or controlled mode where the data transfer occurs in response to interrogation from a ship or competent authority.


    1. The AIS should comprise:
          1. a communication processor, capable of operating over a range of maritime frequencies, with an appropriate channel selecting and switching method, in support of both short and long-range applications;
          2. a means of processing data from an electronic position-fixing system which provides a resolution of one ten thousandths of a minute of arc and uses the WGS-84 datum;
          3. a means to automatically input data from other sensors;
          4. a means to input and retrieve data manually;
          5. a means of error checking the transmitted and received data; and
          6. Built-In Test Equipment (BITE).
    1. The AIS should be capable of:
          1. providing information automatically and continuously to a competent authority and other ships, without the involvement of the ship’s personnel;
          2. receiving and processing information from other sources, including that from a competent authority and from other ships;
          3. responding to high priority and safety-related calls with a minimum of delay;
          4. providing positional and manoeuvring information at a data rate adequate to facilitate accurate tracking by a competent authority and other ships.

User interface
To enable a user to access, select and display the information on a separate system, the AIS should be provided with an interface conforming to an appropriate international marine interface standard.

For the purpose of ship and message identification, the appropriate Maritime Mobile Service Identity (MMSI) number should be used.

The information provided by the AIS should include:

  1. Static Information:
      1. IMO number (where available)
      2. Call sign & name
      3. Length and beam
      4. Type of ship
      5. Location of the position-fixing antenna on the ship (aft of bow and port or starboard of centreline)
  2. Dynamic Information:
      1. Ship’s position with accuracy indication and integrity status
      2. Time in UTC (Date to be established by receiving equipment.)
      3. Course over ground
      4. Speed over ground
      5. Heading
      6. Navigational status (e.g. NUC, at anchor, etc. – manual input)
      7. Rate of turn (where available)
      8. Optional – Angle of heel (if available)
        (Field not provided in basic message)
      9. Optional – Pitch and roll (if available)
        (Field not provided in basic message)
  3. Voyage related:
      1. Ship’s draught
      2. Hazardous cargo (type) (As required by competent authority)
      3. Destination and ETA (at Master’s Discretion)
      4. Optional – Route plan (Waypoints)
        (Field not provided in basic message)
  4. Short safety-related messages

Information update rates for autonomous mode
The different information types are valid for a different time period and thus need a different update rate:

  • Static information: Every 6 min and on request
  • Dynamic information: Dependant on speed and course alteration according to table given below
  • Voyage related information: Every 6 min, when data has been amended and on
  • Safety-related message: As required

Ship Reporting Capacity: 

The system should be able to handle a minimum of 2000 reports per min to adequately provide for all operational scenarios envisioned.

A security mechanism should be provided to detect disabling and to prevent unauthorised alteration of input or transmitted data. To protect the unauthorised dissemination of data, the IMO guidelines
(Guidelines and Criteria for Ship Reporting Systems (Resolution MSC.43(64))) should be followed.

Permissible Initialisation Period
The installation should be operational within 2 min of switching on.

Power Supply:

  •  The AIS and associated sensors should be powered from the ship’s main source of electrical energy.
  • In addition, it should be possible to operate the AIS and associated sensors from an alternative source of electrical energy.

Technical Characteristics of AIS
The technical characteristics of the AIS such as variable transmitter output power, operating frequencies (dedicated internationally and selected regionally), modulation, and antenna system should comply with the appropriate ITU-R Recommendations.

References for IMO Performance Standards for AIS:

Notes on IAMSAR VOLUME III: Mobile Facilities, with updated contents



IAMSAR Volume III is intended to be carried aboard rescue units, aircraft and vessels to help performance of SAR duties as support members, OSC (on-scene coordinator) functions and SAR aspects involving their own emergencies. Thus it provides guidance on SAR aspects to all these three categories.

Purpose of IAMSAR Vol III

The purpose of the International Aeronautical and Maritime Search and Rescue Manual for Mobile Facilities, which is intended for carriage on board search and rescue units, and on board civil aircraft and vessels, is to provide guidance to those who:
– operate aircraft, vessels or other craft, and who may be called upon to use the facility to support SAR operations
– may need to perform on-scene coordinator functions for multiple facilities in the vicinity of a distress situation
– experience actual or potential emergencies, and may require search and rescue (SAR) assistance.

Contents of IAMSAR Vol III (Updated)

As per IMO MSC Circular, MSC.1/CIRC.1594 Amendments to IAMSAR Manual dated May 25, 2018 the contents of IAMSAR Volume III are as follows:

  • Foreword
  • Abbreviations and Acronyms
  • Glossary
  • Section 1 : Overview of the SAR system
  • Section 2: Distress alerts and messages
  • Section 3: Medical assistance
  • Section 4: Vessel emergencies at sea
  • Section 5: Aircraft emergencies
  • Section 6: Initial action by assisting vessels
  • Section 7: Initial action by assisting aircraft
  • Section 8: On-scene communications
  • Section 9: On Scene Coordinator
  • Section 10: Multiple aircraft SAR operations
  • Section 11: Aircraft Coordinator
  • Section 12: Searching
  • Section 13: Rescue action plan
  • Section 14: Rescue or assistance by vessels
  • Section 15: Rescue or assistance by aircraft
  • Section 16: Vessel/ helicopter operations
  • Section 17: Underwater search and rescue
  • Section 18: Rescue on land
  • Section 19: Intercepts
  • Section 20: Survivors
  • Section 21: Deceased persons
  • Section 22: Public relations
  • Section 23: Training
  • Appendix A: Regulation V/33 of the International Convention for the Safety of Life at Sea, 1974, as amended
  • Appendix B: Search action message
  • Appendix C: Factors affecting observer effectiveness
  • Appendix D: Standard format for search and rescue situation report (SITREP)
  • Appendix E: SAR briefing and debriefing form
  • Appendix F: Own emergency
  • Appendix G: Rendering assistance
  • Appendix H: Multiple aircraft SAR operations

Important abbreviations and definitions mentioned in IAMSAR Volume III

ACO: AIRCRAFT COORDINATOR: A person who coordinates the involvement of multiple aircraft in SAR operations.
TAS: TRUE AIR SPEED: Speed of air craft through air mass. TAS corrected for wind speed gives ground speed.
SC: SEARCH and rescue COORDINATOR: SCs are top level SAR mangers. Each state may have one or more SCs, who could be person or an agency.
OSC: ON SCENE COORDINATOR: Person who is designated to coordinate search and rescue within a specified area.
RCC: RESCUE COORDINATION CENTRE: A unit responsible for promoting efficient organization of SAR services and for coordinating the conduct of SAR operations within a SAR region.
ARCC: AERONAUTICAL RCC: An RCC dealing with aeronautical SAR incidents.
MRCC: MARITIME RCC: An RCC dealing with maritime SAR incidents.
JRCC: JOINT RCC: An RCC responsible for both aeronautical and maritime SAR incidents.
RSC: RESCUE SUB CENTRE: A unit subordinate to a RCC established to complement the latter according to particular provisions of the responsible authorities.
RESCUE: An operation that comprises of retrieval of persons in distress, providing for their medical and other needs and finally delivery to place of safety.
SEARCH ACTION PLAN: Message, normally developed by the SMC for passing instructions to SAR facilities and agencies participating in a SAR mission.
RESCUE ACTION PLAN: A plan for rescue operations normally prepared by the SMC for implementation by OSC and facilities on-scene.

SITREP: Situation Report. It gives information about on-scene mission progress and conditions. SITREPs are used by SAR facilities to keep OSC informed, and by OSC to keep SMC informed and by SMC to keep superiors, RCCs and RSCs informed The standard format of SITREP is given in Appendix D of IAMSAR Volume III.
SMC: SAR MISSION COORDINATOR: The official temporarily
assigned to coordinate response to an actual or apparent distress situation.
SRR: SAR REGION: An area of defined dimensions, associated with a RCC, within which SAR services are provided.
SRU: SEARCH and RESCUE UNIT: A unit composed of trained personnel and provided with equipment suitable for the expeditious conduct of SAR operations.
SART: SEARCH AND RESCUE TRANSPONDER: A survival craft transponder that, when activated, sends out a signal automatically when a pulse from a nearby radar reaches it. The signal appears on the interrogating radar screen and gives the bearing and distance of the transponder from the interrogating radar for SAR purposes.

TS: TRACK SPACING: Most search patterns consist of parallel tracks or sweeps covering a rectangular area. The distance between adjacent parallel search tracks is known as track spacing. The track spacing is used in all search patterns except for sector search pattern, It is denoted by “ S ”.
DATUM: A geographic point, line or area used as a reference in search planning.
CES: COAST EARTH STATION: Maritime name for an INMARSAT shore-based station linking SESs with terrestrial communication networks.
CSP: COMMENCE SEARCH POINT: Point, normally specified by the SMC, where a SAR facility is to begin its search pattern.
LUT: LOCAL USER TERMINAL: It is an earth receiving station that receives beacon signals relayed by Cospas-Sarsat Satellites, processes them to determine the location of the beacons and forward the signals.
COSPAS SARSAT SYSTEM: A satellite system designed to detect distress beacons transmitting on frequencies 121.5 MHz and 406 MHz
ELT: EMERGENCY LOCATOR TRANSMITTER: Aeronautical radio distress beacon for alerting and transmitting homing signals.
SafertyNET: Communications service provided via Inmarsat for promulgation of MSI, including shore to ship relays of distress alerts and communication for SAR.

AMVER (Automated Mutual assistance VEssel Rescue system):

  • Amver is one of many ship reporting systems. It is a world-wide system operated exclusively to support SAR and make information available to all RCCs.
  • There is no charge for vessels to participate in, nor for RCCs to use, Amver.
  • Many land-based providers of communications services world-wide relay ship reports to Amver free of charge.
  • Any merchant vessel of 1,000 gross tonnes or more on any voyage of greater than 24 hours is welcome to participate.
  • Information voluntarily provided by vessels to AMVER is protected by the US Coast Guard as commercial proprietary data and made available only to SAR authorities or others specifically authorised by the ship involved.


It could be national or regional in nature and is looked after by one or more SCs (SAR Coordinators).
SCs are top level SAR managers having overall responsibility. (VOLUME I)
They are established by SCs. Each RCC has its own area with well defined dimensions, known as SRR (SAR Region) and RSC has its own SRS (SAR Sub-Region). Maritime SRRs are depicted by IMO and Aeronautical SRRs are depicted by ICAO. RCC could be MRCC or ARCC or JRCC.
SMC (SAR MISSION COORDINATOR): During SAR incident RCC chief or his designee takes the role of SMC. This
function is temporary and lasts only for the duration of the incident. Because of the close proximity in the nature of work, RCC and SMC are used interchangeably. SMC makes search action plan, rescue action plan, specifies CSP, coordinates the operation with adjacent RCCs when appropriate, and prepares final reports among other SAR related duties.
OSC (ON SCENE COORDINATOR): If SMC is not designated OSC performs additional duties of SMC till the times SMC is deputed. Normally this duty carried out by ship master unless more capable SRU is available. Among its duties are: Receive search & rescue action plans from SMC or make them himself if no SMC is deputed.
Make SITREPS. Coordinate on scene communications and operations of all
SAR facilities.
Thus, SAR has three levels of coordination:

Level 1: SAR Coordinator (SCs)

SAR Coordinator (SCs) are the top level SAR managers; each State normally will have one or more persons or agencies for whom this designation may be appropriate.

Duties of SCs

SCs have the overall responsibility for:

  • establishing, staffing, equipping and managing the SAR system
  • establishing RCCs and rescue sub-centres (RSCs)
  • providing or arranging for SAR facilities
  • coordinating SAR training
  • developing SAR policies.

Level 2: SAR Mission Coordinator (SMC)

  • Each SAR operation is carried out under the guidance of an SMC. This function exists only for the duration of a specific SAR incident and is normally performed by the RCC chief or a designee. The SMC may have assisting staff.
  • The SMC guides a SAR operation until a rescue has been effected or it becomes apparent that further efforts would be of no avail.
  • The SMC should be well trained in all SAR processes, be thoroughly familiar with the applicable SAR plans, and:
    • gather information about distress situations
    • develop accurate and workable SAR action plans
    • dispatch and coordinate the resources to carry out SAR missions.

Duties of SMC

IAMSAR Volume III enlist the duties of SAR Mission Coordinator, which are as follows:

  1. obtain and evaluate all data on the emergency
  2. ascertain the type of emergency equipment carried by the missing or distressed craft
  3. remain informed of prevailing environmental conditions
  4. if necessary, ascertain movements and locations of vessels and alert shipping in likely search areas for rescue, lookout and/or radio watch
  5. plot the areas to search and decide on methods and facilities to be used
  6. develop the search action plan and rescue action plan as appropriate
  7. coordinate the operation with adjacent RCCs when appropriate
  8. arrange briefing and debriefing of SAR personnel
  9. evaluate all reports and modify action plans as necessary
  10. arrange for refuelling of aircraft and, for prolonged search, make arrangements for the accommodation of SAR personnel
  11. arrange for delivery of supplies to sustain survivors
  12. maintain in chronological order an accurate and up-to-date record
  13. issue progress reports
  14. determine when to suspend or terminate the search
  15. release SAR facilities when assistance is no longer required
  16. notify accident investigation authorities – if applicable, notify the State of registry of the aircraft missing or distressed craft
  17. prepare a final report.

Level 3: On Scene Coordinator (OSC)

When two or more SAR facilities are working together on the same mission, one person on-scene may be needed to coordinate the activities of all participating facilities. The SMC designates an OSC, who may be the person in charge of a:

  • SRU, ship or aircraft participating in search, or nearby facility in position to handle OSC duties.
  • The person in charge of the first facility to arrive at the scene will normally assume the OSC function until the SMC arranges for the person to be relieved.

Duties of OSC

  1. Coordinate operations of all SAR facilities on-scene.
  2. Receiving the search action plan or rescue plan from the SMC (SAR Mission Co-ordinator) or planning the search or rescue operation, if no plan is otherwise available.
  3. Modifying the search action or rescue action plan as the situation on-scene dictates, keeping the SMC advised.
  4. Coordinating on-scene communications.
  5. Monitoring the performance of other participating facilities.
  6. Ensuring operations are conducted safely, paying particular attention to maintaining safe separations among all facilities both surface and air.
  7. Making periodic situation reports (SITREPs) to the SMC. The reports should include but not be limited to:Weather and sea conditions.
  8. Advising the SMC to release the facilities no longer required.
  9. Reporting the number and names of survivors to the SMC.
  10. Providing the SMC with the names and designations of facilities with survivors on board.
  11. Reporting which survivors are in each facility.
  12. Requesting additional SMC assistance, when necessary (e.g. medical evacuation).
  13. Receive search action plan or rescue action plan from the SMC or plan the same, if no plan is otherwise available.
  14. Coordinate on scene communications. SAR facilities will normally report to OSC. SAR facilities should be in possession of a copy of International Code of Signals,
  15. Monitor the performance of other participating facilities.
  16. Make periodic situation reports (SITREPs).
  17. Maintain a detailed record of the operation.
  18. Maintain communication with SMC
  19. The results of search to date.
  20. Any future plans or recommendations
  21. Maintaining a detailed record of the operation:On-scene arrival and departure times of SAR facilities, other vessels and aircraft engaged in the operation.
  22. Areas searched
  23. Track spacing used
  24. Sightings and leads reported
  25. Actions taken
  26. Results obtained
  27. No advice received from these authorities can set aside the duties of any master as set forth in regulation V/33 of SOLAS 1974 (see appendix A).

Rendering Assistance

On receiving a distress message, following immediate action should be taken:

  • Acknowledge distress message
  • If possible, gather relevant information from craft in distress (position, type and identity of craft, type of cargo onboard, POBs, nature of distress, type of assistance required etc.)
  • Maintain continuous listening watch on international distress frequencies.
  • Maintain communication with distressed craft and convey relevant information about own vessel (Position, identity and speed of own vessel, ETA to site of distress etc.)
  • Use all available means to be aware of the latest position of the distressed craft.
  • On reaching closer post extra look outs to keep the craft in sight.
  • Establish contact with SMC and convey all information, updating, as necessary.

Planning and Conducting the Search (Search Action Plan (SAP))

The SMC typically provides the search action plan. The OSC and ACO (if designated) and facilities on-scene implement the search action plan (see example message in appendix B)

Search Action Plan message consists of six parts:

  • Situation
    • a brief description of the incident
    • position of the incident, and time that it occurred
    • number of persons on board (POB)
    • primary and secondary search objects
    • amount and types of survival equipment
    • weather forecast and period of forecast
    • SAR facilities on-scene
  • Search area(s) (presented in column format)
    • area designation, size, corner points, centre point, and circle radius
    • other essential data
  • Execution
    • SAR facility identification, parent agency, search pattern, creep direction, commence search points, and altitude
  • Coordination required
    • designates the SMC, OSC and ACO
    • SAR facility on-scene times
    • desired track spacing and coverage factors
    • OSC and ACO instructions (e.g. use of datum marker buoys)
    • SAR facility change of operational coordination (SAR facility follows coordinating guidance of SMC, OSC and/or ACO)
    • parent agency relief instructions
  • Communications
    • coordinating channels
    • on-scene channels
    • monitor channels
    • method for OSC and/or ACO to be identified by SAR facilities
    • press channels, if appropriate
  • Reports
    • OSC reports of on-scene weather, progress, and other SITREP information, using standard SITREP format
    • parent agencies to provide summary at the end of daily operations (hours flown, area(s) searched, and coverage factor(s)).

Rescue Action Plan

Rescue Action Plan is also prepared by SMC for implementation by OSC and SAR facilities. The plan may be conveyed in Rescue Action message. At times, however, the plan may also be prepared by OSC.
The parts of the RAP message are exactly similar to those for SAP message except that “Search area” is replaced by “Rescue area”.

Ship reporting systems and vessel tracking

Ship reporting systems have been established by several States. Ships at sea may be the only craft near the scene of a distressed aircraft or vessel.

  • A ship reporting system enables the SMC to quickly:
  • identify vessels in the vicinity of a distress situation, along with their positions, courses, and speeds
  • be aware of other information about the vessels which may be valuable (whether a doctor is on board, etc.)
  • know how to contact the vessels
  • improve the likelihood of rapid aid during emergencies
  • reduce the number of calls for assistance to vessels unfavourably located to respond
  • reduce the response time to provide assistance.
  • Masters of vessels are urged or mandated to send regular reports to the authority operating a ship reporting system for SAR and other safety-related services.
  • Additional information on operators of ship reporting systems may be obtained from RCCs.
  • Automatic identification system (AIS) and long-range identification and tracking (LRIT) transmissions are also important for providing shore authorities with real or near real time vessel tracking data to support search and rescue.
  • AMVER:
    • Amver is one of many ship reporting systems. It is a world-wide system operated exclusively to support SAR and make information available to all RCCs.
    • There is no charge for vessels to participate in, nor for RCCs to use, AMVER.
    • Many land-based providers of communications services world-wide relay ship reports to AMVER free of charge.
    • Any merchant vessel of 1,000 gross tonnes or more on any voyage of greater than 24 hours is welcome to participate.
    • Information voluntarily provided by vessels to AMVER is protected by the US Coast Guard as commercial proprietary data and made available only to SAR authorities or others specifically authorised by the ship involved.

Situation Reports (SITREP)

    • provide earliest notice of an emergency
    • pass urgent essential details when requesting assistance
    • pass amplifying or updating information during SAR operations
  • The OSC uses SITREPs to keep the SMC informed of on-scene mission progress and conditions, and addresses SITREPs to the SMC unless otherwise directed. Search SAR facilities use SITREPs to keep the OSC informed.
  • The SMC uses SITREPs to keep superiors, other RCCs, and any other interested agencies informed.
  • Where pollution or threat of pollution exists from the vessel or aircraft casualty, the agency tasked with environmental protection should be an information addressee on SITREPs from the SMC.
  • Initial SITREPs should be transmitted as soon as details of an incident become clear enough to indicate SAR involvement.
  • Each SITREP concerning the same incident should be numbered sequentially.
  • A standard SITREP format is shown in appendix D of IAMSAR Volume III.
  • SITREPs prepared on-scene usually provide the following information:
    • Identification
    • Situation
    • Action taken
    • Future plans
    • Status of case

Planning a Search at Sea


  • It will be necessary to establish a datum, or geographic reference, for the area to be searched. The following factors should be considered:
    • reported position and time of the SAR incident
    • any supplementary information such as DF bearings or sightings
    • time interval between incident and arrival of SAR facilities
    • estimated surface movements of the distressed craft or survival craft, depending on drift. (The two figures following this discussion are used in calculating drift.)
  • The datum position for the search is found as follows:
    • drift has two components: leeway and total water current
    • leeway direction is downwind
    • leeway speed depends on wind speed
    • the observed wind speed when approaching the scene may be used for estimating leeway speed of liferafts by using the graph following this discussion. (Persons in the water (PIW) have no leeway while liferaft stability and speed vary with or without drogue or ballast.)
    • total water current may be estimated by using the computed set and drift of vessels at or near the scene
    • drift direction and speed is the vector sum of leeway and total water current
  • drift distance is drift speed multiplied by the time interval between the incident time, or time of the last computed datum, and the commence search time
  • datum position is found by moving from the incident position, or last computed datum position, the drift distance in the drift direction and plotting the resulting position on a suitable chart.
IAMSAR-Volume-iii-Datum Graph
Datum Graph


Most search patterns consist of parallel tracks or sweeps covering a rectangular area. The difference between adjacent tracks is called the track spacing.
Recommended uncorrected TSs are provided in IAMSAR manual along with correction factors which depend on weather conditions and search object. Uncorrected TS is multiplied by correction factor to get the
recommended correct TS.TS does not apply to sector search pattern. TS is denoted by S. S is given by:

S = SU x f w

Where, SU is TS uncorrected
fw is weather correction factor.

Uncorrected TS is given in tabular form for different search objects for different meteorological visibilities. There are three tables, one each for merchant vessel, helicopters and fixed wing aircrafts. Maximum value of fw is 1 which is for normal weather (i.e. Su = S) and as weather gets worse factor fw becomes less thus reducing value of S.

Searching Speed (V)

All search facilities should proceed at same speed as directed by OSC. This is normally the maximum speed of the slowest ship. This speed may, however, have to be reduced in restricted visibility.

Search Area (A)

Search radius is computed using 2 methods:
1. If search is to commence immediately, assume R = 10 NM
2. If time is available, compute the area as advised in following steps:
i. Compute area A, a certain craft can cover at a speed V in given time T: A = V x T x S; where S = TS , T = Time for which
craft will search, V = Craft’s speed
ii. The total area At which can be covered by several crafts is
given by sum total of areas covered by each craft:
At = A1 + A2 + A3 = A4 + ……………..
iii. If all crafts are searching at same speed for the same amount of
time, then:
At = NA; where N is the number of crafts involved.
iv. Search Area radius ( R ) is then given by:
R = √At / 2
v. Draw circle with datum as centre and R as radius. Draw tangents to the circle to form square. If several search facilities
are involved, then divide the square into sub-areas and assign the sub-areas as appropriate to different search facilities.

Choice of Search Patterns

  • Search patterns and procedures must be pre-planned so as to enable minimum delay, risks and maximum efficiency. Standard search patterns have been devised to meet differing situations.
  • They are based on visual search and have been selected for simplicity and effectiveness.
  • The OSC should obtain a search action plan from the SMC via the RCC or RSC ASAP. OSC should keep the SMC informed at regular intervals and whenever the situation has changed.
  • The choice of search pattern will be decided by following factors:
    • Type and size of distressed craft.
    • Meteorological visibility.
    • Sea and weather conditions.
    • Time of day or night.
    • Time of arrival at datum and size of area to be searched.
    • Number and type of assisting crafts available.

Type of Search Patterns listed in IAMSAR Volume III

Expanding Square Search (SS):


1. It is most effective when location of object is known.
2. CSP is always the datum.
3. It is appropriate for small vessels and boats to search for survivors in water with little or no leeway.
4. Accurate navigation is required. First leg is usually oriented directly into the wind to minimize navigational errors.
5. Area involved being small, the procedure must not be used by multiple aircrafts at same altitudes or multiple sea crafts.

Sector Search (VS):


1. It is most effective when position of search object is accurately known
and search area is small.
2. It is used to search a circular area centred on datum point. Due to small area involved procedure must not be used simultaneously by multiple vessels/ aircrafts.
3. An aircraft and a vessel may be used together to perform independent sector searches of same area.
4. A suitable marker (smoke float or radio beacon) may be dropped at datum point for reference or navigational aid mark the centre.
5. For vessels, search pattern radius is usually between 2 nm and 5 nm and turn is 120 degrees, normally to starboard. For aircraft the search pattern radius is usually between 5 nm and 29 nm.

Track Line Search (TS)

1. It is normally used when an aircraft or a vessel has disappeared without a trace along a known route.
2. It is often used as initial search effort due to ease of planning and implementation.
3. Consists of rapid and reasonably thorough search along intended route of the distressed craft.
4. Search may be along one side of track line and return in the opposite direction on the other side (TSR: track line search, return).
5. Search may be along the intended track and once on each side, then , then search finally continues on its way and does not return (TSN: track line search, not return).
6. Aircrafts are frequently used for TS due to their high speed.

Parallel Sweep Search (PS)

1. It is used to search a large area when survivor location is not known.
2. Most effective over water or flat terrain.
3. The CSP is in one corner of the sub area, one half tracks inside the
rectangle from each of the two sides forming the corner.
4. Search legs are parallel to each other and to the long sides of the sub
5. It can be used by 2, 3, 4, 5 or more ships.

Creeping Line Search Coordinated (CSC)

1. The aircraft does most of the searching, while ship steams along a
course at a speed as directed by OSC.
2. It gives a higher probability of detection than can normally be attained
by an aircraft searching alone.
3. Ship speed varies according to speed of aircraft and size of the

Contour Search (OS)

1. Used around mountains and in valleys when sharp changes in elevation make other patterns not practical.
2. Search is started from highest peak and goes from top to bottom with new search altitude for each circuit.
3. Search altitude intervals may be 150m to 300m.
4. If the mountain cannot be circled, successive sweeps at the same altitude intervals as listed above should be flown along its side.
5. Valleys are searched in circles, moving the centre of the circuit one track spacing after each completed circuit.

Rescuing Survivors

  • The OSC coordinates the rescue action, directing the most suitably equipped rescue units to move in. And other units stand by and assist as required.
  • When survivors are rescued, it is important that full details of the casualty are obtained quickly and passed to the OSC, so that the search is not called off prematurely. Their medical and nutritional needs must also be made.

Preparations carried out on board en route to render the assistance to the distressed vessel as per IAMSAR Volume III

On-Board Preparations:

  • A vessel en route to assist a distressed craft should prepare for possible
  • SAR action on scene, including the possible need to recover people
  • from survival craft or from the water. See “Recovery of survivors by
  • assisting vessels” later in this section.
  • Masters of vessels proceeding to assist should assess the risks they may
  • encounter on scene, including the risks such as those associated with
  • leaking cargo, etc. Information should be sought as necessary from the
  • distressed craft and/or from the RCC.

A vessel en-route to assist a distressed craft should have the following equipment ready for possible use:

  • Life-saving and rescue equipment:
    • lifeboat
    • inflatable liferaft
    • lifejackets
    • survival suits for the crew
    • lifebuoys
    • breeches buoys
    • portable VHF radios for communication with the ship and boats deployed
    • line-throwing apparatus
    • buoyant lifelines
    • hauling lines
    • non-sparking boat hooks or grappling hooks
    • hatchets
    • rescue baskets
    • stretchers
    • pilot ladders
    • scrambling nets
    • copies of the International Code of Signals
    • radio equipment operating on MF/HF and/or VHF/UHF and capable of communicating with the RCC and rescue facilities, and with a facility for direction finding (DF)
    • supplies and survival equipment, as required
    • fire-fighting equipment
    • portable ejector pumps
    • binoculars
    • cameras
    • bailers and oars
  • Signalling Equipment:
    • signalling lamps
    • searchlights
    • torches
    • flare pistol with colour-coded signal flares
    • buoyant VHF/UHF marker beacons
    • floating lights
    • smoke generators
    • flame and smoke floats
    • dye markers
    • loud hailers
  • Preparations for medical assistance, including:
    • stretchers
    • blankets
    • medical supplies and medicines
    • clothing
    • food
    • shelter
  • Miscellaneous Equipment:
    • If fitted, a gantry crane for hoisting on each side of ship with a cargo net for recovery of survivors.
    • Line running from bow to stern at the water’s edge on both sides for boats and craft to secure alongside.
    • On the lowest weather deck, pilot ladders and manropes to assist survivors boarding the vessel.
    • Vessel’s lifeboats ready for use as a boarding station.
    • Line-throwing apparatus ready for making connection with either ship in distress or survival craft.
    • Floodlights set in appropriate locations, if recovery at night.

Conclusion of Search

  • The OSC must decide, in consultation with SMC, when the rescue is completed and must inform assisting ships, thus relieving them of their obligation to remain.
  • The OSC should also inform the CRS of all relevant details. Before leaving the scene of successful rescue, life rafts and life-jackets etc. should be retrieved or sunk and other floating debris should be the subject of radio warning.
  • If search is unsuccessful and all reasonable hope of rescuing survivors has passed, the OSC, in consultation with the SMC, will call off the search and dismiss assisting units. A radio message asking all ships to keep look out is advisable.


Aircraft can assist by dropping markers, smoke or flame floats, and survival equipment, consisting of nine person dinghy and two bags of supplies. They can carry out an air search, locate a casualty, keep it under observation and guide surface craft to it. Flying-boats may be able to alight and pick up survivors. Helicopters may also pick up survivors.


  • IAMSAR Volume III, Download Here
  • MSC.1/Circ.1594 Amendments to IAMSAR Manual dated 25 May 2018. Read Here
  • The IMO Website