These Instructions are issued by the Maritime and Coastguard Agency for the
guidance of radio surveyors in the survey and inspection of radio installations
on fishing vessels for the purpose of ensuring compliance with the various
Statutory Instruments. They also indicate to owners, skippers and crew,
shipbuilders and radio installation companies the procedure adopted for the
survey and acceptance of radio installations.
Statutory provisions The principal statutory provisions concerning radio installations are
contained in:
The Merchant Shipping Act 1995;
The Wireless Telegraphy Act 1949 and 1967;
The Merchant Shipping (EPIRB Registration) Regulations 2000 (SI
No. 1850);
The Merchant Shipping (Radio) (Fishing Vessels) Regulations 1999
(SI No. 3210) (referred in this Chapter as the “Radio Regulations”);
The Fishing Vessels (Codes of Practice) Regulations 2017 (SI No.
943) A comprehensive list of current Merchant Shipping Acts and
Regulations is issued at regular intervals and published by the MCA in the
form of a Marine Guidance Note. They can be downloaded from the MCA
In these instructions the following definitions apply:
Authorised Persons
An organisation authorised or recognised by the Secretary of State to perform
the survey of radio equipment on United Kingdom ships and, as appropriate,
issue approval certification
Authority To Operate (ATO)
Issued by the MCA, to authorise a radio certificate holder to operate a UK
licensed radio station.
MSIS 27/CH 12/Rev 1017/Page 1 of 46
Basic Equipment
Equipment forming part of the radio installations provided on a fishing vessel
to comply with Regulation 10 and Regulations 11,12,13,14 and schedule 4, as
appropriate, of the Radio Regulations.
Directive Vessel
A fishing vessel which is new and over 24m length, or existing and over 45m
length, where new means built on or after 1 January 1999.
Digital Selective Calling being a technique using digital codes which enables a
radio station to contact other stations.
Duplicate Equipment
Equipment, additional to basic equipment, forming part of radio installations
provided on a fishing vessel.
Emergency Position-Indicating Radio Beacon (EPIRB)
A station in the mobile service, the emissions of which are intended to
facilitate search and rescue operations.
Existing Installation
An installation wholly installed on board before the date on which the present
Regulations enter into force irrespective of the date on which acceptance by
the respective Administration takes effect; or,
An installation part of which was installed on board before the date of entry
into force of the present Regulations and the rest of which consists either of
parts installed in replacement of identical parts, or parts which comply with the
requirements of this chapter.
Float Charging
A battery-charging arrangement where a battery, and all equipment connected
to the battery, are simultaneously supplied with electrical energy from an
automatic charging device.
Functional Requirements
The functional requirements of the GMDSS as specified in regulation 8 of the
radio Regulations.
MSIS 27/CH 12/Rev 1017/Page 2 of 46
The Global Maritime Distress and Safety System.
The radio frequencies between 4 and 30 MHz allocated by the ITU to the
maritime mobile services.
International Fishing Vessel Certificate, issued in accordance with the
Torremolinos Protocol for all fishing vessels 24m length and above.
International Maritime Organization
4, Albert Embankment
The Organisation established by the Convention of the International Maritime
Satellite Organisation (INMARSAT) adopted on 3 September 1976.
International NAVTEX Service
The co-ordinated broadcast and automatic reception on 518 kHz of maritime
safety information by means of narrow-band direct-printing telegraphy using
the English language.
International Telecommunication Union
Maritime Safety Information
Navigational and meteorological warnings, meteorological forecasts and other
urgent safety related messages broadcast to ships.
The radio frequencies less than 4 MHz allocated by the ITU to the maritime
mobile services.
New Installation
Any installation which is not an existing installation.
MSIS 27/CH 12/Rev 1017/Page 3 of 46
Non Directive Vessel
A fishing vessel over 12 length which is new but less than 24m length, or
existing but less than 45m length, where new means built on or after 01
January 1999
Radio Operator
A person holding a certificate specified in the Radio Regulations (ITU) as
Radio Regulations (ITU)
The Radio Regulations annexed to, or regarded as being annexed to, the
most recent International Telecommunication Convention which may be in
force at any time.
Radio Regulations
Unless otherwise specified, the Merchant Shipping (Radio) (Fishing Vessels)
Regulations 1999, SI No. 3210, as may be amended from time to time.
Collectively or individually, those Regulations regarding radio matters that are
applicable to the vessel involved.
United Kingdom Fishing Vessel Certificate, issued in accordance with the
Code of Safe Working Practice (MSN 1770) for fishing vessels between 15m
and 24m length
The radio frequencies between 30 MHz and 300 MHz
Application of the Radio Installations Regulations The Radio Regulations apply to:
Sea-going United Kingdom fishing vessels.
Other seagoing Directive fishing vessels while they are in the United
Kingdom or the territorial waters thereof. At sea means any time when a fishing vessel is not securely
moored in a safe berth.
MSIS 27/CH 12/Rev 1017/Page 4 of 46
Recommended guidance
Recommended guidance concerning radio installations for fishing vessels are
contained in:
Admiralty List of Radio Signals GMDSS – NP285, vol 5;
Code of Safe Working Practices for Merchant Seamen;
The IEE Regulations for the Electrical Equipment of Ships;
Merchant Shipping Notices;
Marine Guidance Notices;
Marine Information Notes;
British Standard Specification for Limits and methods electromagnetic
interference generated by marine equipment and installations. (BS
1597: 1985); and
Code of practice for radio interference suppression on marine
installations (BS 5260): 1975 Confirmed Nov 1981).
Powers of surveyors Powers of surveyors are derived from The Merchant Shipping Act
1995 (Section 256). Sections 257, 258 and 259 provide the powers to require the
production of ship’s documents, to inspect ships and their equipment, and to
board ships at any reasonable time for the purpose of checking compliance
with statutory requirements. A Radio Surveyor appointed by the Secretary of State for Transport
may under Sections 256 of the Merchant Shipping act 1995, inspect a vessel
and, where appropriate, confirm that it is properly provided with radio
installations and satisfies the other requirements in conformity with the
Regulations. A Radio Surveyor, whilst undertaking work on behalf of the Maritime
and Coastguard Agency shall not:
offer comments concerning individual suppliers of marine radio
equipment or their capabilities in respect of repairs nor be personally
involved in any repairs which may need to be carried out in
connection with that survey;
MSIS 27/CH 12/Rev 1017/Page 5 of 46
undertake any sales activity whatsoever, whether at a regional office
or main office, in connection with any survey or inspection performed;
pass any information whatsoever regarding a potential sale or sales
connected with any survey or inspection performed, to any third party
(except the MCA for monitoring purposes) or to any person or
department within the surveyor’s parent company.
Detention In cases where a ship to which the Regulations apply, does not
comply with the relevant Regulations, the ship may be liable to be detained. In
the event of a ship not complying with the Regulations, the Radio Surveyor
must consult with the local MCA Consultant Fishing Vessel Surveyor who will
determine whether the vessel should be detained and what further action
should be taken against the vessel. Section 95 of the Merchant Shipping Act 1995 as amended provides
for the detention of an unsafe ship. Guidance on detention is contained in
procedure MCA 810 and the Instructions to Surveyors on Inspection Policy.
Improvement and Prohibition Notices Detention is effective if the ship is about to go to sea, and is mainly
used to prevent departure of a ship until defects affecting her safety have
been remedied. It is not appropriate for stopping unsafe practices or
preventing dangerous activities in port, and in some cases it is too severe a
course of action to deal with some infringements of statutory requirements. An
alternative course of action is available under the Merchant Shipping Act
1995, which allows the serving of Improvement and Prohibition Notices.
These should be issued in accordance with procedure MCA 860 and the
Instructions to Surveyors on Inspection Policy (MSIS 38).
Non-United Kingdom Ships In general, United Kingdom Regulations require standards on nonUnited Kingdom ships to be equivalent to those on United Kingdom ships and
make provisions for measures to be taken to rectify any deficiencies or, in
extreme cases, for ships to be detained. Where an activity involves a risk of
serious injury or pollution a Prohibition Notice can be issued to a non-United
kingdom ship provided the activity involved is one to which relevant Statutory
Instruments apply. However an Improvement Notice can be issued only where
there is a breach of specific regulation and the surveyor should first satisfy
himself that the regulation involved does in fact apply to non-United Kingdom
MSIS 27/CH 12/Rev 1017/Page 6 of 46
Referral to Maritime and Coastguard Agency
Should a difficulty arise in an area covered by the Regulations, Merchant
Shipping Notices, Marine Guidance Notices or these Instructions the matter
should be referred to the:
Maritime and Coastguard Agency
Navigation Safety Branch
Spring Place 105 Commercial Road
Southampton SO15 1EG
Tel: +44 (0) 020381 72432
Application for Exemptions The Secretary of State for Transport is empowered to exempt any
fishing vessel from any of the requirements of the Radio Regulations.
Applications for exemption may be sent by the owners or their representatives
directly to the Maritime and Coastguard Agency's Navigation Safety Branch,
or through the Regional Consultant Fishing Vessel Surveyor. Any such
application should contain detailed reasons for regarding the statutory
requirements as unnecessary or unreasonable. Exemptions are to be considered following procedure MCA 292 and
the Survey Policy Instructions.
Issue of Exemption Certificate If complete, partial or conditional exemption is granted by the MCA,
an exemption certificate will be issued to the applicant stating the extent of the
exemption, and where appropriate, the conditions upon which it has been
granted. Exemption certificates will normally remain in force for the same
period as any certificate relating to the radio installation. A copy of any
exemption certificate shall be retained aboard the vessel to which it is granted
and must be made available to a Radio Surveyor or MCA Surveyor at any
survey or inspection of the radio station.
Non - UK Registered Ships Where a vessel, not registered in the United Kingdom, holds an
exemption certificate, the Radio Surveyor or MCA Surveyor should check that
the exemption falls within the terms of the Directive or, in the case of a non
Directive vessel, would be considered reasonable applied to a UK vessel.
Where there is reason to doubt the acceptability of the exemption, the matter
should be referred to Navigation Safety Branch.
MSIS 27/CH 12/Rev 1017/Page 7 of 46
12.1.10 Fees Fees are set by the individual Authorised Person to carry out Radio
Surveys. Vessel owners should liaise direct with these bodies regarding the
12.1.11 Safety
To confirm that personnel are not placed at risk or equipment is not
inadvertently damaged during survey, a responsible person representing the
owners, capable of operating the equipment should be present during survey
or other inspection of radio installations. If the owner is not so represented the
Surveyor should not proceed unless he is satisfied that it is safe to do so and
has the agreement of the master or representative of the owner.
Survey Arrangements
Application for radio survey Application for a survey should be made directly by the Owner to the
Authorised Person and not through class. A list of Authorised Persons is
available at The Authorised Persons are permitted by MCA to conduct the
surveys and inspections of radio installations on UK registered ships and nonUK registered ships in UK ports. The Authorised Person is required to take full
legal responsibility for the actions of the radio surveyors supplied. In any application for an initial survey clear instructions should be
given regarding the GMDSS sea area or areas through which the ship will
pass during its intended voyages. Where any change to the equipment and other items covered by the
survey is to be made or has been made prior to a renewal survey, or where it
is intended to amend the area of operation on the certificate, this information
should be brought to the attention of the Authorised Person at the time of
application. Radio surveyors may be required, as necessary, to perform a survey
of the radio installations on a UK registered ship overseas. Initial and renewal
surveys of UK registered fishing vessels are to be performed by radio
surveyors from the Authorised Person. Annual radio surveys may be
conducted locally in foreign ports by delegated appointment to classification or
other authorised sub-contractors. Radio surveyors performing surveys for
statutory purposes should confirm that all the equipment required under the
Regulations is carried and is fit and ready for use, that the installation is in
MSIS 27/CH 12/Rev 1017/Page 8 of 46
accordance with the Regulations and instructions and that all radio operators
are appropriately qualified.
Submission of drawings (plans & designs)
Shipowners and shipbuilders should submit plans and particulars of the
proposed radio installations for new fishing vessels to the regional Consultant
Fishing Vessel Surveyor who will consult with the Authorised Person agreed
between the Owner and MCA concerning the surveys of radio installations at
the design stage. This will provide an early opportunity to determine, as far as
possible, whether the proposals comply with the Regulations; they should
cover the layout of equipment, wiring and antenna arrangements. These plans
will be treated in confidence.
Issue of Certificates
If entirely satisfied that the applicable Regulations are being met and all fees
due have been paid, the radio surveyor should complete and forward a Report
of Radio Survey MSF 1808 with Record of Equipment MSF 1809 to the MCA
Lead Surveyor for use in connection with the issue of a FV Certificate.
Deficient installations When a Radio Surveyor considers an installation deficient or
defective, a notice in writing (MSF 1603) is to be handed or sent to the owner
or his representative pointing out the defect or deficiency and indicating what
is required to remedy it. All defects and deficiencies must be made good to
the satisfaction of the Radio Surveyor. If defects are sufficiently serious that a completed Report of Survey
(MSF 1808) cannot be issued, or if it should be considered necessary to
invoke further enforcement action, the local Regional Consultant Fishing
Vessel Surveyor must be informed as per 12.1.6 or .7.
Guidelines for Survey
Equipment standards Radio equipment installed on a UK fishing vessel over 12m
registered length should meet the relevant IMO GMDSS requirements and
ITU recommendations and should be of a type approved by the
administration. However, non-directive vessels may continue to comply with the
performance standards listed in MSN 1809, as may be amended. These guidelines reflect to a large extent unambiguous requirements
in accordance with the relevant rules and Regulations, see subsection 12.3.2.
below. Practical installation solutions other than the ones emerging from these
MSIS 27/CH 12/Rev 1017/Page 9 of 46
guidelines may be accepted as long as the IMO requirements are met and the
installation is considered to be equivalent.
Note: - The marine electronics company which installs the radio equipment
should be responsible for giving the radio operators proper familiarisation in
the use of the installed radio equipment before it is put into operation.
Rules and Regulations
These guidelines are prepared in accordance with the following conventions,
regulations, instructions and guidelines:
IMO Resolutions (Performance standards) and IMO Circulars;
ITU (International Telecommunication Union) Radio Regulations
(RR); and
International Standards – ISO 8468 1990 (E), annex A
Drawings (plans and designs) For the radio installations, including those used in lifesaving
appliances, the examination of plans and designs should consist of
the sea areas declared for operation;
the equipment installed to fulfil the functional requirements for the sea
the methods used to confirm the availability of the functional
requirements; and
the arrangements for supply of an emergency source of energy (if
any). Declarations are required from the owner, the owner's representative
or the shipyard as appropriate relating to the following:
The sea area or sea areas through which the ship will operate;
The radio installations which are intended to fulfil the functional
The method or methods adopted to ensure the radio equipment
required by the Regulations complies with the serviceability and
maintenance requirements of the Regulations; and
MSIS 27/CH 12/Rev 1017/Page 10 of 46
The availability, or otherwise, of an emergency source to supply the
radio installations.
General Specified drawings should available well before the work on a new
building or reconstruction of a vessel is started. Insufficient or missing
drawings may result in deficiencies during radio survey and could lead to
expensive repairs costs later. For the radio installation the following drawings should be prepared:
• Antenna drawing;
• Radio arrangement drawing; and
• Wiring diagram. For new buildings the antenna and radio arrangement drawings
should at least be of size 1:50. Approved “as installed” wiring diagram, radio arrangement as well as
antenna drawings should be kept available on board the ship for presentation
during radio survey etc.
Antenna drawings Antenna drawings, or aerial rigging plan, should show all antennae
seen from fore or aft position, the port or starboard position and from above.
This applies to the following antennas:
• All transmitting antennae including location of antenna tuner;
• All receiving antennae including GNSS antennae;
• Radar antennae;
• Satellite communication antennae;
• The location of float-free EPIRBs; and
• AIS antennae When changes are made in the antenna arrangement, modified
antenna drawings should be prepared and submitted to the Authorised Person
for approval.
Radio arrangement drawings (Lay-out of bridge and communication room).
MSIS 27/CH 12/Rev 1017/Page 11 of 46 These drawings should show the location of the following equipment:
Controllers for transmitting distress alerts;
VHF radio installations, including any control units;
MF or MF/HF installation, including any control units, printers etc;
Satellite communication equipment, including terminals, printers etc;
Watchkeeping receivers for VHF ch. 70, 2187.5 kHz, and HF distress
channels in 4, 6, 8, 12 and 16 MHz bands;
NAVTEX and EGC receivers;
Radar transponders and EPIRBs (if located on the navigating bridge
Hand held (two-way) GMDSS VHF transceivers and their chargers;
Emergency light powered from a reserve source of energy to
illuminate the mandatory radio equipment;
Battery charger (for the reserve source of energy); and
Fuse box.
Wiring diagram These drawings should show the following connections etc.:
• Antenna connections;
• Connections to telephone exchange (PABX), fax machine etc;
• Connections to the ships mains, emergency source of energy, and
the reserve source of energy (batteries), and switching systems for all
radio- and radio navigation equipment;
• Which radio equipment (including emergency light) being connected
to each power unit/source;
• Fuses for all radio equipment;
• Uninterruptible Power Supply (UPS) with all connections and fuses, if
installed as power for mandatory radio equipment. (Block diagram
showing how the UPS operates, showing the fuses and switchover
connections to alternative power supplies, by-pass switch etc.);
MSIS 27/CH 12/Rev 1017/Page 12 of 46
• Any connections (interface connections) between satellite navigator/
GNSS and GMDSS radio equipment;
• Battery chargers for the reserve source of energy;
• Connections to gyro (if applicable);
• Type of cables used in the installation; and
• Connections to VDR (if applicable)
Instruction manuals and publications
The following up to date instruction manuals and publications should be
available on board:
Users manual (in English) for all radio equipment and battery
Specifications and battery capacity calculations for the installed
ITU publications according to requirements in the Radio Regulations;
Publications as required by UK flag authorities; Admiralty List of
Radio Signals (NP285); Lists of Coast and Ship stations;
The GMDSS Radio Log Book. For non-Directive vessels, a Simplified
FV Radio Log should be kept; and
A Certificate of Competency for a radio operator ( see para 12.3.11)
and an ATO
Shore Based Maintenance agreement (if appropriate)
Tools and spare parts As a minimum requirement the ship should have the following tools
and spare parts readily available on board:
Spare fuses for all radio equipment, battery circuit and main fuses
where safety fuses (“melting” fuses) are used;
Reserve emergency lamps;
Tools necessary for simple servicing;
Acid specific density meter if the ship is fitted with lead acid
accumulators; and
MSIS 27/CH 12/Rev 1017/Page 13 of 46
Multi-meter. If the ship makes use of the “on board maintenance” method, it
should be equipped with extensive test equipment and spare parts, which
enable maintenance and repairs of all mandatory radio equipment while at
Maintenance requirements Ships equipped with GMDSS radio installation should meet specific
requirements as to maintenance methods for the radio installation.
Irrespective of sea areas, the ship should not leave harbour without being able
to transmit distress alert ship-to-shore by at least two separate and
independent radio communication systems. Every Directive fishing vessel shall ensure availability of equipment
by using at least one of the following methods (MSN 1801 refers):
• duplication of equipment;
• shore-based maintenance; and
• at-sea electronic maintenance capability.
Duplication of equipment The following additional equipment should be installed in sea areas
A3 and A4:
• VHF with DSC controller;
• Approved satellite ship earth station or complete MF/HF radio
telephony station with DSC and NBDP. (See note)
(IMO Resolution A.702(17))
Note: - Ships in the A3 sea areas may choose between duplication with either
complete MF/HF transceiver or approved satellite ship earth station. Ships in
regular trade in sea areas A4 must duplicate with a complete MF/HF
installation. Ships in sea area A4 which are not in regular trade in that area
may duplicate with approved satellite ship earth station, provided a MF/HF
installation is used as main station.
Shore-based maintenance To be acceptable:
The shipping company/ship must have a written agreement with a
marine electronic company or be able to present a written
MSIS 27/CH 12/Rev 1017/Page 14 of 46
declaration/plan showing how shore-based maintenance is to be
carried out. Maintenance contracts must comply with MGN 417.
(IMO Resolution A.702(17), Annex, item. 3)
A Fishing Vessel Certificate issued by an Administration should, in
general, be a sufficient proof that satisfied adequate maintenance
arrangement has been made.
(IMO Resolution, A.702(17) and Com/circ. 117)
At-sea electronic maintenance If the shipowner chooses at sea electronic maintenance, personnel
with necessary qualifications and authorisation for servicing the equipment
must be present on board. All necessary instruments and spare parts for
repair of all radio equipment must also be available when the ship is at sea. In
the case of United Kingdom ships, for the purpose of the Regulations an
officer or crew member shall be deemed qualified to
carry out radio maintenance if he or she holds –
• a Radio Maintenance Certificate granted by the Secretary of State; or
• a certificate recognised by the MCA as being equivalent to the
certificate in (i) above.
(IMO Resolution. A.702(17))
Ship Station Radio Licence A ship station radio licence in accordance with the Radio
Regulations should be issued to the ship. The licensee (normally the shipowner) is responsible for applying
for a radio licence in due time before the installation take place.
(RR. Art. 18) Applications should be made directly to the Spectrum Licencing
Tel: 020 7981 3181 or 0300 123 1000
Fax: 020 7981 3235
Textphone: 020 7981 3043 or 0300 123 2024 – Please note these
numbers will only work with special equipment used by people who
are deaf or hard of hearing
MSIS 27/CH 12/Rev 1017/Page 15 of 46
Note: - The Maritime Mobile Service Identity (MMSI) number stipulated in the
radio licence should be coded into the DSC equipment. If a satellite EPIRB is fitted or Personal Locator Beacon carried then
it must be coded and registered, see MSN 1816. The UK can only accept
beacons coded using MID codes 232 233 234 or 235. Accepted UK protocols
UK serialised – where the beacon has a unique serial number;
UK Maritime Mobile Service Indicator (MMSI) – allocated to the
vessel; and
UK location protocols – for GPS models All these identities must be changed when a ship is transferred from
another flag, and appropriate steps taken to ensure databases held ashore
are kept current. UK Beacon registry is at MRCC Falmouth:
Tel. +44 1326 211 569 fax +44 1326 319264
Guidance on UK Beacon registration is contained in MSN 1816.
12.3.8 Application for activation of satellite equipment
The licensee is also responsible for registration and service activation of
satellite ship earth station.
12.3.9 De-activation of satellite equipment when transferring a ship to
foreign flag
When transferring a ship to foreign flag, the licensee/shipowner must inform
the appropriate Licensing Authority immediately concerning de-activation of
satellite equipment.
Initial and annual radio survey, issuance, renewal and
endorsement of Fishing Vessel Certificates (FVC)
Guidance on survey of radio installation is given in IMO
Res.A.948(23), noting the following text in this Resolution.
"The radio survey should always be performed by a fully qualified radio
surveyor who has adequate knowledge of the IMO’s relevant
Convention, and associated performance standards, and appropriate
ITU Radio Regulations. The radio survey should be carried out using
suitable test equipment capable of performing all relevant measurements
required by these guidelines."
MSIS 27/CH 12/Rev 1017/Page 16 of 46 MCA has permitted a number of Authorised Persons to undertake
radio surveys on fishing vessels in UK and abroad. Their report is required for
the MCA surveyor to issue a UKFVC or IFVC, so the surveyor must undertake
radio surveys during initial and renewal MCA surveys.
12.3.11 Radio operators It is considered as very important that the responsible radio
operators are properly instructed and trained in how to use the GMDSS radio
equipment. For Directive vessels, a GMDSS restricted operator’s certificate
(ROC) is required for operation in sea area A1, and a general operator’s
certificate (GOC) is required for operation in sea areas A2/A3/A4. UK
certificates of competency include an authority to operate (ATO). Foreign
certificate holders without certificates of equivalent competency (CEC) are
required to apply to MCA for an ATO. The radio licence and certificate for the radio operator(s), including
ATO, should be checked during the survey. New Certificates of Competency
(CoC) and Certificates of Equivalent Competency (CEC) will include the ATO.
Older CoCs and foreigners without a CEC, should have a separate ATO. On United Kingdom non-Directive vessels a GMDSS Short Range
Certificate (SRC) can be accepted for operation in A1 area, and GMDSS Long
Range Certificate (LRC) for operations in A1, A2, A3 or A4 areas.
12.4. Functional Requirements
General The functional requirement of the GMDSS is that “Every ship, while
at sea, should be capable of transmitting ship-to-shore distress alerts by at
least two separate and independent means each using a different radio
communication service”. It should be possible to initiate such alerts from the
position from which the ship is normally navigated. Under certain conditions the satellite EPIRB may be used to meet
this requirement if installed close to the navigation bridge or if it can be remote
activated from the bridge. In addition to the above mentioned requirements, it should be
possible to initiate the transmission of DSC distress alerts from the navigation
bridge on VHF, and also on MF or HF, provided that the MF or HF equipment
is obligatory in the trade area of the ship. All ships should keep continuous watch on VHF channel 70 by use
of a DSC receiver.
MSIS 27/CH 12/Rev 1017/Page 17 of 46 Ships with MF requirements should in addition keep continuous
watch on MF DSC 2187,5 kHz and on HF DSC distress and safety channels if
required to have HF radio equipment installed. IMO Resolution MSC.131(75) requires all vessels to maintain, when
practical, a continuous listening watch on VHF channel 16 until such time as
the Maritime Safety Committee may determine the cessation of this
requirement. Except for area A1, watch should also be kept with NAVTEX and/or
with EGC receiver. The watch should be kept at the position from which the
ship is normally navigated.
12.4.2 Sea areas (definitions) A1 means an area within the radiotelephone coverage of at least
one VHF coast station in which continuous DSC alerting is available, as may
be defined by a Contracting Government. A2 means an area, excluding sea area A1, within the
radiotelephone coverage of at least one MF coast station in which continuous
DSC alerting is available, as may be defined by a Contracting Government. A3 means an area, excluding sea areas A1 and A2, within the
coverage of an Inmarsat geostationary satellite in which continuous alerting is
available (76 °N and 76 °S). A4 means an area outside sea areas A1, A2 and A3.
MSIS 27/CH 12/Rev 1017/Page 18 of 46
GMDSS equipment requirements for Directive vessels
VHF with DSC
DSC watch receiver channel 70
MF telephony with MF DSC
DSC watch receiver MF 2187,5 kHz
Inmarsat ship earth station with EGC receiver
MF/HF telephony with DSC and NBDP
DSC watch receiver MF/HF
Duplicated VHF with DSC
Duplicated Inmarsat SES
Duplicated MF/HF telephony with DSC and NBDP
NAVTEX receiver 518 kHz
EGC receiver
Float-free satellite EPIRB
Radar transponder (SART)
Hand held GMDSS VHF transceivers
Outside NAVTEX coverage area.
New vessels 24m-45m & existing vessels over 45m : 1 set
New vessels over 45m : 2 sets
New vessels 24m-45m & existing vessels over 45m : 2 sets
New vessels over 45m : 3 sets
Inmarsat E-EPIRB cannot be utilised in sea area A4.
Refer to section 12.11 for GMDSS equipment for non-Directive vessels.
12.5. Basic Equipment
General requirements
Every radio installation should:
be so located that no harmful interference of mechanical, electrical or
other origin affects its proper use;
be so located as to ensure electromagnetic compatibility (EMC) and
avoid harmful interference to other equipment and systems;
be so located as to ensure the greatest possible degree of safety and
operational availability, with warning notice when appropriate;
be protected against the harmful effects of water, extremes of
temperature and other adverse environmental conditions;
be provided with emergency lighting, which is independent of the
main and emergency sources of electrical power for the illumination of the
radio controls;
MSIS 27/CH 12/Rev 1017/Page 19 of 46
be clearly marked with the ships call sign, MMSI number and other
identities as appropriate; and
be so located that no magnetic compass lies within the stated
Compass Safe Distance of the equipment. Where no such marking
exists, it should be sited at a distance of more than 700mm away.
Radio equipment spares should be stowed more than 1m from a
magnetic compass;
Navigational Safety VHF Control of the VHF used for navigational safety must be available at
the conning position (in the front of the navigation bridge), and where
necessary, from the wings of the bridge. Portable VHF equipment may be used to provide navigational
safety from the wings of the bridge.
Marking of radio equipment and notices All radio equipment should be duly marked with type designation.
The marking should be clearly visible when the equipment has been installed. The radio installation should be duly marked with the ship's call
sign, the ships station identity and other codes applicable for the use of the
radio equipment. DSC operation procedures should be posted near the DSC
equipment on the navigation bridge. Emergency procedures should be posted
near the relevant equipment on the bridge. “GMDSS Operating Guidance for Masters of Ships in Distress
Situations” and the procedure “False alerts”, both drawn up by IMO, should be
posted on the navigation bridge.
12.5.4 Emergency lights All mandatory radio equipment should have reliable emergency
lighting powered from a reserve source of energy, which normally is the radio
batteries. This light should preferably be red and give adequate illumination of
the controls for safe operation of the radio equipment, and the working table
for reading and writing. Means should be provided for dimming any light source on the
equipment which is capable of interfering with navigation, i.e. by adjustable
light or by use of a curtain etc. during night-time. For VHF transceivers located openly in the front of the bridge, a
screened light concentrating on each single piece of equipment, should be
used. Scale illumination (powered from a reserve source of energy) may be
MSIS 27/CH 12/Rev 1017/Page 20 of 46
accepted provided it is sufficient for the operation of call control devices both
on the VHF transceivers and the VHF transceivers and the DSC controllers. Ceiling light may be used for equipment located in a separate radio
workstation, providing it is not dazzling the navigator on watch.
(IMO Resolution A.694(17), item 3.3.) The emergency light should have its own fuse circuit and fuses in
each circuit. These fuses should be connected before of the main fuses in
order to prevent blown main fuses to cause interruption of the emergency
light. Switches for emergency lights must be properly marked.
12.5.5 Recommended installation
In order to meet all requirements and recommendations concerning the
location of all units included in a GMDSS radio installation, it is recommended
to establish either a “radio work station” in connection with the navigating
bridge, or a separate “communication office” outside the navigation bridge
with remote controls on the bridge. It must be emphasised, however, that the
suggestions in subsections 12.5.6 – 12.5.8 below are to be considered as
guidelines only. Other solutions and combinations are equally acceptable as
long as the general requirements and recommendations outlined are fulfilled.
(COM/Circ. 105 and ISO 8468: 1990(E))
12.5.6 Radio work station The workstation should be located in the aft of the navigation bridge
so that the navigator has an over all view of the navigation while operating the
radio equipment. If the workstation and the rest of the navigation on bridge are
separated by a wall it must be made of glass or fitted with windows. There
must be no lockable door between the workstation and the navigation bridge. When the workstation is being used during night time, a curtain
must be provided in order to avoid dazzling effect from the lights. All mandatory radio equipment (except mandatory VHF, see should be located in the radio workstation. Watch receivers may
alternatively be located elsewhere on the navigation bridge.
Note: - It is essential that satisfactory watch (clearly audible signals/visual
alarms) can be maintained at the position from which the ship is normally
navigated. If it is not possible to maintain satisfactory watch, alarm indicators
on MF or MF/HF and Inmarsat equipment, including EGC printer, must be
located outside this work station.
MSIS 27/CH 12/Rev 1017/Page 21 of 46
(IMO Resolutions A.664(16), A.807(19) Annex item 3.2 regarding EGC, and
A.610(15), A.806(19) Annex D item 8 regarding MF and MF/HF DSC
requirements) MF/HF RF power amplifiers should be located in a separate and
screened room. Antenna tuners should, as a general rule, be located outdoors
below the antenna.
12.5.7 Communication office The communication office may be located as required by the
shipping company, e.g. in connection to the skipper’s office. It should be
possible to make public calls and perform general radio communications on
MF or HF and/or through satellite from the communication office, if such calls
cannot be made from a suitable location elsewhere on the ship. All equipment for written correspondence, as well as telephone
services for MF/HF and Inmarsat, should be located in the communication
office. The remote operation panels for the mandatory equipment must be
located in a central position on the navigation bridge, in order to fulfil the
requirements for transmitting distress alerts from the navigation bridge.
Note: - Consideration should also be given to the requirements for
navigational safety communication and subsequent distress communications
on MF or HF. When MF/HF DSC is included in the mandatory basic or
duplicated radio equipment, it must be possible to conduct distress- and
safety communications from the navigating position, and the MF/HF DSC
controller must be installed in this position.
(IMO Resolutions A.804(19) and A.806(19)) Watch receivers and NAVTEX/EGC receivers should be located on
the navigation bridge. VHF transceivers with DSC used for navigational safety should be
located in the front of the navigation bridge.
12.5.8 Ships with integrated bridge system (IBS) Ships constructed to satisfy the IBS requirements for single-manned
navigating bridge should have the operation panels for mandatory GMDSS
equipment installed as close to the conning position as possible. Equipment for the transfer of radiotelephone calls via radio (VHF,
MF or MF/HF) or satellite to other areas of the ship should be placed close to
the other GMDSS equipment near the conning position.
MSIS 27/CH 12/Rev 1017/Page 22 of 46 It should be possible also to operate printed communications (data
communications via radio and/or Inmarsat) from other areas of the ship.
12.5.9 Ships with integrated radio communication systems (IRCS) The IRCS is a system in which individual radio communication
equipment and installations are used as sensors, i.e. without the need for their
own control units, providing outputs to and accepting inputs from the
operator’s position, called workstations. Such workstations are called
“GMDSS workstations” if they include control and monitoring of all equipment
and installations provided on a ship for the GMDSS which are also suitable for
general radio communications. The IRCS workstation should be installed in a
console located in a central position on the navigation bridge. Transmitting
and receiving equipment may be located outside the navigation bridge. The IRCS should comprise at least two GMDSS workstations each
connected to each GMDSS radio communication sensor over a network or
connection system. At least two printers should be installed. All requirements
laid down in SOLAS 1974, as amended, chapter IV, should be fulfilled.
(IMO Resolution A.811(19))
GMDSS Radio Equipment
Location of VHF transceivers and VHF DSC controllers VHF with DSC forming part of the mandatory VHF communication
equipment for safety of navigation should be located at the conning position.
This equipment may be connected to several remote control units, i.e. on the
wings of the navigation bridge, provided that the navigating bridge has priority.
If such “combined” equipment is chosen, it should be possible to transmit DSC
distress alert from the conning position. If the ship is equipped with extra VHF transceiver (without DSC)
with channels required for navigational safety, located in the conning position,
another central location of the mandatory DSC VHF equipment on the
navigation bridge (in navigating position) can be accepted.
Note: - With regard to the location of equipment and distress alerts, the same
requirements also apply to the duplicated DSC VHF equipment for ships in
sea areas A3 and A4. The duplicated VHF transceiver can, however, be
located in the “navigating position” instead of in the conning position.
(IMO Resolution. A.702(17), Annex, item 2.1.) In order to conduct power measurements, easy access to the
antenna output of each equipment should be provided.
(IMO Resolution A.746 (18))
MSIS 27/CH 12/Rev 1017/Page 23 of 46
Continuous watch on DSC VHF channel 70
Continuous watch on DSC VHF channel 70 can be met by: a separate VHF channel 70 watch receiver. It should not be muted
or interrupted when using other radio equipment, or a dedicated watch receiver combined with the VHF transceiver. It
should be installed so as to maintain watch even when the VHF equipment is
used for telephony, or VHF with DSC permanently locked on channel 70 for reception and
transmission of DSC calls only. To deal with other correspondence on other
channels, an additional VHF-transceiver must be installed, which may be
without the DSC-function.
(IMO Resolutions A 694 (17) and A 803 (19), Com/Circ. 105)
Location of MF/HF transceivers If the equipment is main or duplicated equipment, it must be
possible to activate the distress alert from the navigation bridge. If the
equipment can be remote operated from other positions on board the ship,
priority should be given to the unit on the navigation bridge. With regard to a MF installation, the requirement for DSC distress
alerts on 2187,5 kHz can also be fulfilled by a remote-activated MF control
unit locked on 2187,5 kHz with alert activated from the navigation bridge.
Note: - DSC on MF is required in sea areas A2, A3 and A4, irrespective of
selected radio equipment solution. It should therefore always be possible to
activate the DSC distress alerts on 2187,5 kHz from the navigation bridge. If combined MF/HF radio equipment is chosen as mandatory
GMDSS equipment, it should also be possible to activate the distress alert
from the navigating bridge on the mandatory HF DSC frequencies. If MF/HF installation is chosen as duplicated equipment (MF/HF
option) on a ship with A3, there is no requirement for an extra DSC watch
(COM/Circ. 105/Clarification) RF power amplifiers should, as a general rule, not be located in the
navigation bridge area. Location in such area may, however, be accepted if it
can be granted that the EMC requirements are fulfilled. The antenna tuner
should, as a general rule, be located in an outdoor position below and close to
the antenna.
(IMO Resolution A. 813(19))
MSIS 27/CH 12/Rev 1017/Page 24 of 46 The MF or MF/HF transmitter should be equipped with an
instrument or other provisions indicating antenna current or power delivered to
the antenna.
(IMO Resolutions A.804(19) and A.806(19) Annex 6.1) If the transmitter antenna is not permanently connected to the
transmitter, it should be automatically connected before the distress alert is
Watch-keeping receivers for DSC Depending on the trade area and mandatory radio equipment of the
ship, continuous watch is required via separate receivers for DSC channel 70,
MF DSC 2187.5kHz and HF DSC 8414.5 kHz, as well as minimum one of the
frequencies 4207.5 kHz, 6312 kHz, 12577 kHz and 16804.5 kHz. The watch receiver for VHF DSC channel 70, MF DSC 2187.5 kHz
and HF DSC scanning receiver must be located so that the alarm is clearly
audible and visible all over the navigation bridge.
(IMO Resolution A.804(19), COM/Circ 105) It must be possible to read the DSC alert messages on the
navigation bridge. The printer (if any) or display etc. may be common for all
DSC watch receivers, provided that messages coming in simultaneously are
arranged in queue and printed as soon as the printer/display is ready.
(IMO Resolutions A.803(19), A 804(19 and A.806(19)) Easy access to the antenna connector should be possible in order
to conduct test of the equipment by means of measuring instruments.
Note: - There is no requirement for a duplicated MF/HF DSC watch receiver
for ships in sea areas A3 or A4 when maintenance method “duplication of
equipment” is used.
(IMO Resolution A.702(17), Annex item 2.1)
Watch-keeping on MF or MF/HF DSC Continuous watch on the MF DSC distress frequency 2187.5 kHz is
to be kept by:
• a separate DSC watch receiver locked on 2187.5 kHz;or
• a dedicated watch receiver combined with the MF radiotelephone.
MSIS 27/CH 12/Rev 1017/Page 25 of 46
Note: - If DSC operation is desirable on other frequencies, an additional
scanning receiver should be provided. Other frequencies than those used for
distress and safety should not be included in the receiver dedicated for DSC
emergency watchkeeping. A single DSC decoder may be used to serve both
the DSC watch and the additional scanning receiver.
(COM/Circ.105) Continuous watch on MF/HF DSC distress and safety frequencies to
be kept by:
• a separate DSC MF/HF DSC scanning receiver for distress and safety
frequencies only; or
• a dedicated MF/HF DSC scanning watch receiver for distress and
safety DSC frequencies only combined with the MF/HF radiotelephone.
(COM/Circ. 105)
Note: - If DSC operation is desirable on other frequencies, an additional
scanning receiver should be provided. The receiver may be combined with the
watch receiver for MF DSC. A single DSC decoder may be used to serve both
the DSC distress and safety frequency scanning receiver and the additional
scanning receiver only if continuous watch for distress and safety calls can be
maintained. (COM/Circ. 105) Watch-keeping on DSC calling frequencies
For watch-keeping on other frequencies than distress and safety frequencies
(national and international DSC calling frequencies), a separate scanning
receiver should be provided.
Note: Ships in sea areas A2 should be able to transmit and receive general
radio communications on MF or MF/HF telephony or NBDP or Inmarsat ship
earth station. Ships in sea area A2, which is equipped in accordance with the
minimum requirements (i.e. VHF and MF with DSC), should be provided with
equipment for listening and calling on national and international MF DSC
calling frequencies. Alternatively, they may be provided with Inmarsat
equipment in order to fulfil the “general” and “public” correspondence
requirements. According to IMO’s Performance Standards, Res. A.804(19)
and A.806(19), it is required that the DSC equipment should have possibilities
as to be used also for “public correspondence”. For ships in sea areas A3 and
A4 the installed equipment (MF/HF or Inmarsat, depending on installation
solution) should also be used for common radio communications. In these sea
areas the requirements for “general” or “public correspondence” are normally
fulfilled either by using the HF or Inmarsat equipment.
MSIS 27/CH 12/Rev 1017/Page 26 of 46
Satellite ship earth station (SES) If the equipment is the main station or duplicated equipment, it must
be possible to activate the distress alert from the navigation bridge. The terminal and telephone, if any, may be placed in a “radio work
station” in connection with the navigation bridge or in a separate
communication office. The satellite terminal and/or external printers may also be located
elsewhere in the ship.
Note: - Attention should be made to IMO Resolution A807(19), Annex 3.2
regarding Inmarsat-C, which has the following text:
“It should be possible to initiate and make distress calls from the position
from which the ship is normally navigated and from at least one other
position designated for distress alerting”. The words “one other position designated for distress alerting” is
only actual for ships which have defined an additional place/room on board to
be such “other position”. Normally it will be accepted that Inmarsat C
equipment is installed in the “radio work station” if it is provided with facilities
for conducting distress alerts from the navigation bridge. It is, however,
recommended that the Inmarsat C terminal, including additional equipment,
should be located on the navigation bridge in order to make it possible to
conduct follow-up distress communication from this position. Skippers should be made aware of measures to ensure
communications are maintained with Rescue Co-ordination Centres during
distress, ref. MGN 304
Connection of external located data terminal to mandatory
Inmarsat C ship earth station in the GMDSS If the licensee/shipowner wants to connect the mandatory InmarsatC terminal i.e. to the ship’s PC-network or to an outside located data terminal,
all mandatory GMDSS requirements in accordance with SOLAS 1974, as
amended, should always be fulfilled. In that case, the dedicated printer should be connected permanently
to the output of the mandatory Inmarsat terminal’s printer output. A manually
operated and duly marked switch, located near the Inmarsat terminal, should
be installed to disconnect the Inmarsat terminal from the external equipment.
MSIS 27/CH 12/Rev 1017/Page 27 of 46
NAVTEX and EGC (Enhanced Group Call) receiver The printer for NAVTEX and Inmarsat EGC receiver should be
located on the navigation bridge. As mandatory equipment in the GMDSS,
these receivers should also, as a general rule and in the same way as
required for other permanent installed equipment, have their own permanent
installed power supplies with fuse circuits/fuses, cf. subsection 12.9.1.
Antenna and antenna cable should also be permanently installed. The mandatory requirement for an EGC receiver may be combined
with Inmarsat equipment. It is recommended that a dedicated EGC receiver is
used, enabling continuous reception of MSI (Maritime Safety Information)
messages independent of whether the Inmarsat equipment is being used or
not. “Class 3 EGC” is included in the Inmarsat C, but only shares the antenna
with this equipment and functions in parallel with and separate of the Inmarsat
C equipment.
(IMO Resolution A.701(17))
Satellite float-free EPIRB
The satellite float-free EPIRB should be located/installed so that the following
requirements are fulfilled:
• The EPIRB should - with greatest possible probability - float free and
avoid being caught in railings, superstructure etc., if the vessel sinks;
• The EPIRB should be located so that it may be easily released
manually and brought to the survival craft by one person. It should
therefore not be located in a radar mast or any other places which can
only be reached by vertical ladder;
(IMO Resolutions A.763(18), A.810(19), and A.812(19))
Note: - A float-free EPIRB may also be used to fulfil the requirements
for one piece of equipment (of two), which is capable of transmitting
distress alert to shore from or near the navigating bridge of the ship.
Under such conditions the float-free EPIRB must fulfil the following
additional requirements with regards to location/installation:
• The EPIRB must be installed in the vicinity of the navigation bridge, i.e.
on the wings of the navigation bridge. On smaller fishing vessels a
location on the top of the wheelhouse may be accepted.
(Com/Circ. 105)
MSIS 27/CH 12/Rev 1017/Page 28 of 46
• It may be possible to activate the EPIRB remotely from the bridge. If
remote activation is used, the EPIRB should be installed so that it has
unobstructed hemispherical line of sight to the satellites.
(Com/Circ. 105)
Note: - It should be considered that the main function of the EPIRB is
float-free activation. If the additional requirements mentioned above
cannot be met without reducing the reliability of the float-free activation,
priority must be given to this requirement. Alternatively, two float-free
EPIRBs should be installed.
• The EPIRB should be equipped with a buoyant lanyard suitable for use
as a tether to life raft etc. Such buoyant lanyard should be so arranged
as to prevent its being trapped in the ship’s structure.
(IMO Resolution A.810(19))
• The EPIRB should be marked with the ship’s call sign, serial number of
EPIRB, MMSI number (if applicable),15 Hex ID, and battery expiry
• It should be noted that Inmarsat EPIRBs are currently being phased out
and the service for these ceased in December 2006.
Radar transponders (SART) New and existing vessels over 45m require at least two SARTs.
New vessels over 24m but under 45m may have one SART. The radar transponders should be placed in brackets on both sides
of the vessel and preferably visible from the navigation bridge. It must be easy
to bring the transponders to the lifeboats or liferafts. A visible location inside
the navigation bridge, close to the outer doors, is recommended. Alternatively
one radar transponder should be placed in each survival craft. Under the
requirements of Torremolinos, vessels operating in the Northern regions
additionally require each survival craft to be permanently equipped with a
SART. Liferafts thus fitted, should be clearly marked accordingly on the valise.
The SART should be provided with a pole or other arrangement compatible
with the antenna pocket in the survival craft in order to fulfil the required height
of at least 1 metre above sea level. The SARTs should have waterproof marking with operational
instructions, battery expiry date and the vessel’s name and call sign.
Hand held (Two-way) GMDSS VHF transceivers New and existing vessels over 45m require at least three two-way
VHFs. New vessels over 24m but less than 45m may carry two.
MSIS 27/CH 12/Rev 1017/Page 29 of 46 Obligatory hand held VHF transceivers including their emergency
batteries (primary batteries normally of Lithium type) should be located in a
central and easily accessible position on the navigation bridge. If such
equipment is placed in a lockable cabinet, it must be possible to get easy
access to the hand held VHF transceivers without the use of tools. Primary batteries must be sealed for use only in emergency
situations and marked by the supplier with battery expiry date. The battery
will be considered as exhausted and used if its seal is broken, and a new
battery will be requested during radio survey, ref. the IMO requirement for 8
hours operation in emergency situations. If hand held VHF with re-chargeable NiCad batteries (secondary
batteries) are used for on-board communications, chargers for these batteries
should be provided.
(IMO Resolutions A.762(18) and A.809(19)) Hand held VHF transceivers should have waterproof marking with
the ship’s name and call sign. The primary battery must be marked with an
expiry date. Channel numbers must be stated on the equipment.
12.6.12 Hand held VHF transceivers and communications from the
wings of the navigation bridge
In order to fulfil the requirements, mandatory hand held GMDSS VHF can be
used. (see section Alternatively a simplex VHF transceiver (single
frequency only) or remote controlled units with channel selector, loudspeaker
and microphone may be installed in these positions. These remote controlled
units must be controlled by a VHF installed in the front of the navigation
(COM/Circ 105 Clarification)
GNSS – Global Navigational Satellite System In ships, where GNSS/GNSS should be installed, automatic
updating of the ship’s position into the DSC equipment and Inmarsat
equipment should be possible. If such automatic updating is not possible, it is
required to enter the ship’s position manually into relevant GMDSS equipment
at intervals not exceeding 4 hours whenever the ship is under way. If the GNSS is connected to the GMDSS equipment, it should
(similar to the mandatory GMDSS equipment) be supplied with energy from
the reserve source of energy/batteries.
MSIS 27/CH 12/Rev 1017/Page 30 of 46
Connection of Navigational Sensors GNSS - Receiver
A GNSS receiver must be connected to the relevant radio communication
equipment (DSC controller, GMDSS satellite equipment) in order to provide
information on the ship’s position continuously and automatically to the radio
equipment. Heading sensor If the GMDSS satellite equipment requires automatic antenna
adjustment according to ships heading, a heading sensor on the gyro should
be connected. In this case the gyro should also be supplied with energy from the
reserve source of energy/batteries.
Antenna Installation
General Special attention should be paid to the location and installation of
the different antennae on a ship in order to ensure effective and efficient
communication. Incorrectly installed antennae will degrade the performance of
the radio equipment and will reduce the range of radio communications. A rigging plan of the fitted aerials should be kept available on board
every fishing vessel, showing the elevation and plan views of the
arrangements, see section 12.3.3 The dangers from exposed aerial lead-ins should be considered see
MGN 330.
12.7.2 Location of VHF antennae VHF antennae should be placed in a position which is as elevated
and free as possible, with at least 2 metres horizontal separation from
constructions made by conductive materials. VHF antennae should have a vertical polarisation. Ideally there should not be more than one antenna on the same
level. The location of mandatory VHF antennae should be given priority
compared with mobile telephone antennas. If they are located on the same
level, the distance between them should be at least 5 metres. It is recommended to use double screened cable with a maximum
loss of 3 dB.
MSIS 27/CH 12/Rev 1017/Page 31 of 46 All outdoor installed connectors on the coaxial cables should be
watertight by design in order to give protection against water penetration into
the antenna cable. Any AIS VHF antenna should be installed safely away from
interfering high-power energy sources like radar and other transmitting radio
antennas, preferably at least 3 metres away from and out of the transmitting
beam. Any AIS VHF antenna should be mounted directly above or below
the ship's primary VHF radiotelephone antenna, with no horizontal separation
and with minimum 2 m vertical separation. If it is located on the same level as
other antennas, the distance apart should be at least 5 metres.
12.7.3 Location and choice of MF/HF antennae The mounting arrangement of the antenna or pedestal must be
constructed in order to withstand the strain from swaying and vibration. The
transmitting whip antenna should be installed as vertical as possible. Wire-antennae should be protected against breakage by having a
weak link installed. Whip antennae should be installed as vertical as possible and
located in an elevated position on the ship at least 1 metre away from
conductive structures. Attention must be paid to self-supportive vertical antennae and their
swaying radius. The recommended minimum length of the antenna is 8 metres. The down lead from the base of the antenna to the antenna tuner
should be insulated and run as vertically as possible and not less than 45
degrees towards the horizontal plane. The transmitting antenna should have an insulation resistance to
earth which is recommended to be of more than 50 MΩ in dry weather and of
no less than 5MΩ in humid weather (transmitter to be disconnected when
12.7.4 Location of antenna tuner for MF/HF transceiver
The antenna tuner should normally be located externally (outdoors) and as
close to the antenna as possible, and so that the down lead wire/cable from
the antenna should be as vertical as possible.
MSIS 27/CH 12/Rev 1017/Page 32 of 46
12.7.5 Receiving antennae As a general rule, all receivers including watch-keeping receivers
should have their own separate antenna. Antennae for watch-keeping receivers should be located as far
away as possible from MF/HF transmitting antennae in order to minimise
receiver blocking.
12.7.6 Satellite communication antennae
General In general, satellite antennae must be located so that they have a
360 degree free view for the satellite at all times. In practical terms this can be
difficult to achieve due to shadow sectors from nearby structures. It is recommended for Inmarsat-A , B and F-77 antennae (stabilised
directional antennae) that communication should be maintained with the
satellite down to an elevation of minus 5 degrees. For Inmarsat-C (omnidirectional antenna) it is recommended that communication should be
maintained with the satellite down to an elevation of minus 5 degrees in the
fore and aft direction and minus 15 degrees in the port and starboard
Satellite communication antenna installation The following guidelines should be observed in order to fulfil the
above recommendations:
• The antenna should be located at the top of the radar mast; or
• On a pedestal, in the radar mast, or on the top deck so that:
• for directive antennae; shadows from constructions, especially
within a distance of 10 metres, is maximum 6 degrees; and
• for omnidirectional antennas; shadows from constructions,
especially within a distance of 1 metre, is maximum 2 degrees.
• Antennae must be installed in a readily accessible location;
• They should not be located in an area where they can be damaged by
heat and smoke;
• The satellite antenna must not be located on the same plane as the
ships radar antenna;
• GNSS antennae should not be located close to or on the same plane
as the Inmarsat antenna; and
MSIS 27/CH 12/Rev 1017/Page 33 of 46
• Consideration should be given to installing the Inmarsat antenna on a
suitable pedestal.
(Ref. IMO Resolutions A.698(17), A-663(16), A 807(19) and Inmarsat
Design and Installation Guidelines)
Note: - The mast/or pedestal must be constructed so that vibrations are
reduced as much as possible.
Safe antenna distances The following “safe distance” from Inmarsat antennae to other
antennae and to the compass are recommended:
• Distance to the HF antenna should be more than 5 metres.
• Distance to VHF antennae should be more than 4 metres.
• Distance to the magnetic compass should be more than 3 metres.
(Cf. the installation manual for the equipment and Inmarsat guidelines)
Inmarsat-C antenna The antenna should be constructed so as to function up to 15
degrees pitch and roll. In order to obtain this result, the antenna should be
located in such position that no objects or constructions down to 15 degrees
below the horizon are degrading the performance of the equipment.
Note: - As it may be difficult to fulfil this recommendation fore-and-aft, the free
area in this direction may be reduced to 5 below the horizon.
(IMO Resolutions A663(16) and A.807(19))
Calculation of distance to obstructions:
MSIS 27/CH 12/Rev 1017/Page 34 of 46 If obstructions such as i.e. mast, funnel etc. is unavoidable, the
following guidelines should apply:
• The distance to the obstruction should be so that the obstruction only
covers a 2 degrees sector.
Note: - In such case the safe distance will be the following: 20 x the diameter
of the obstruction (in metres).
diameter (m)
max. angle 2 degrees
• If two Inmarsat C antennae are installed the vertical distance between
them should be at least 1 meter to eliminate interference.
Antenna cable The manufacturers specifications regarding total attenuation and
maximum DC resistance (short-circuit in one end) must be complied with.
Only double-screened cable should be used.
Antennae for voluntary radio equipment Antennae for voluntary radio equipment may be located on deck,
provided its use does not interfere with antennae of mandatory radio
equipment. When mobile telephone is installed on board ships, special
attention should be made to the facts that some types of mobile telephones
(especially GSM telephone equipment) may interfere with the ship's
navigational equipment (especially GNSS) and other electronic equipment.
Installation of coaxial cables Coaxial cables should be installed in separate ducting and at least
10 cm away from power supply cables. Incorrect installation of cables may change their characteristic
impedance resulting in power reflections, which will attenuate the RF signal
and reduce the efficiency of the radio equipment.
MSIS 27/CH 12/Rev 1017/Page 35 of 46 In VHF antennae the reflected power should not be greater than
10% of the measured output power. The following guidelines should be applied when bending coaxial
• Cables should be crossed at right angles;
• Where there is one bend in a permanent fixture the bending radius
should be 5 times the cables’ outside diameter;
• Where there are several bends, the bending radius should be 10 times
the outside diameter of the cable; and
• When using flexible cable the bending radius should be 20 times the
outside diameter of the cable.
EMC, earthing and screening
Electromagnetic Compatibility (EMC)
General All reasonable and practical steps should be taken to ensure EMC
compatibility between the equipment concerned and other radio
communication and navigational equipment carried on board. In order to avoid
interference the following rules applies:
• Radio installations must not cause harmful interference to other
electronic, electrical or navigational systems on board ships;
• However, these other systems must not cause harmful interference to
the radio installation; and
• In order to avoid electromagnetic noise interference it is essential that
manufacturers guidelines relating to EMC, screening and earthing are
correctly followed.
(IMO Resolutions A694(17) and A.813(19))
Voluntary radio equipment Additional, voluntarily carried Non-GMDSS radio equipment like e.g.
• Mobile telephone;
• Radio amateur stations; and
• Satellite stations
MSIS 27/CH 12/Rev 1017/Page 36 of 46 Operation of such equipment is at the discretion of the master. It
may be installed on the bridge provided that the EMC requirements are
fulfilled and navigation and radio communication is not degraded
12.8.2 Screening of cables
In order to avoid interference the following guidelines should apply with
regards to screening of cables:
• Coaxial down leads must be used for all receiving antennas and the
coax screen should be connected to ground on at least one end;
• All cables within a distance of 2 metres from a transmitting antenna
must be screened and the screen properly earthed in a metal tube or
12.8.3 Earthing
Earthing of radio equipment should be carried out in accordance with
appropriate guidelines for earthing in maritime installations required in
international standards. Great care should be taken in order to fulfil the
following rules:
• Each unit of radio equipment must have a separated earth connection;
• MF/HF antenna tuners must be earthed with either a copper bar or
copper band;
• The earthing bar or strap must be as short as possible, should not be
more than one metre in length, and should be at least 60 mm in width;
• For earthing straps up to 5 metres in length the width should be at least
100 mm (May be relevant on board vessels made of wood or synthetic
• It should be noted that a long earthing strap or bar will act as an
antenna and radiate energy;
• Copper bars and straps should be brazed to the steel bulkhead in order
to eliminate corrosion and vibration and make a good earth connection;
• Great care should be taken when earthing radio equipment on ships
with aluminium superstructures in order to avoid galvanic corrosion. An
approved and acceptable method of earthing should be used on such
Note: - Insufficient earthing of the power amplifier may lead to capacitive and
inductive connections between power cables etc. and cause interference to
MSIS 27/CH 12/Rev 1017/Page 37 of 46
fire alarms, navigational equipment, inter-com. and other equipment. The
transmitter output power may also be reduced.
Sources of energy
Main source of electrical power The main source of electrical power is defined as the ship’s mains.
All the basic and duplicated equipment must have an independent power
supply from the ships mains. The battery charging arrangement used to
charge any batteries associated with the reserve source of energy must also
have an independent supply from the ships mains. It is not advisable to provide the main source of electrical power to
the GMDSS communications equipment through the battery charger. If a fault
occurs in the battery charger, which renders it defective, it may not be
possible to operate the equipment from the ship’s mains. Batteries used in the
reserve source of energy will become discharged eventually leading to loss of
all power supplies.
(IMO Resolution A.702(17) Annex item. 2.3)
Emergency source of electrical power The emergency supply is usually taken from the emergency
generator, but on smaller vessels may be from accumulator batteries. The emergency source must be adequate to operate both the basic
and duplicate equipment (if applicable) for 18 hours.
Reserve source of energy The radio reserve source or sources of energy should meet the
requirements set out in IMO Resolutions A.694(17) and A.702(17), as
applicable. It usually consists of rechargeable batteries and is used to supply
the communication equipment in the event of failure of the ship’s mains and
emergency source of electrical power. All fishing vessels should have a
reserve source or sources of energy for the operation of the basic equipment,
and the duplicated equipment if such equipment is required. The changeover from the ship’s mains or emergency supply to the
reserve source of energy should be done automatically and in such a manner
that both the basic and duplicated communications equipment will be
connected simultaneously. Where the changeover is done manually, the
switch should be readily accessible to the radio operator, clearly labelled and
located on the navigation bridge. Such changeover should not result in the
loss of data stored in memories. One bank of batteries may be acceptable if the capacity is sufficient
to operate both the basic and duplicated radio equipment simultaneously.
MSIS 27/CH 12/Rev 1017/Page 38 of 46
The battery capacity should also be sufficient to operate the gyro (if
applicable), GNSS, and emergency light. Any fault in the radio batteries or the battery charger should not
affect both the basic and duplicated radio equipment and should not prevent
the operation of the radio equipment from the ships mains or emergency
supply. The reserve source of energy must be capable of operating the
radio installation for at least:
• 1 hour on ships provided with an emergency supply which is adequate
to operate the radio communications equipment for a period of 18
hours; or
• 6 hours on ships not provided with an emergency supply as outlined in
(IMO Resolutions A.694(17), A.702(17) – Annex item 2.3, COMSAR/Circ.. 16)
Radio battery capacity When defining the minimum required battery capacity, consideration
should be given to the expected extreme temperatures for the location of the
battery and reduction of its capacity during its lifetime in addition to the loads
which are to be connected to it. The batteries must have enough capacity to operate all the GMDSS
radio equipment for the specific times outlined in above. The total
load for the entire radio installation should be calculated prior to the
installation of any radio batteries for the reserve supply. Where the basic and duplicated radio equipment cannot be
operated simultaneously, the battery capacity should be sufficient to operate
the equipment with the highest power consumption. Where the basic and duplicated radio equipment are connected
simultaneously the battery capacity should be sufficient to meet the average
consumption of all connected equipment including any additional loads such
as printers, VDU’s etc. If the capacity requirement of radio batteries is to be maintained
over their normal life cycle, an extra 40% capacity should be added to the
minimum calculated capacity. When calculating discharge time the following guidelines may be of
• The capacity of a lead acid battery is normally quoted at 20 hours of
discharge at an operational temperature of 20 O C;
MSIS 27/CH 12/Rev 1017/Page 39 of 46
• The capacity at 1 hour discharge is approximately 50% of the capacity
at 20 hours discharge;
• The capacity at 6 hours discharge is approximately 80% of the capacity
at 20 hours discharge;
• For batteries other than the lead acid type the capacity at 1 hour
discharge is approximately 60% of the capacity at 10 hours discharge
and 6 hours discharge will be approximately 92% of the capacity at 10
hours discharge. The capacity of the radio batteries should be checked at intervals
not exceeding 12 months when the ship is not at sea. One method of
checking the capacity is to fully discharge and recharge the batteries using
normal operation current over a period of 10 hours. Assessment of the charge
condition can be made at any time, but it should be done without significant
discharge of the battery when the ship is at sea. Another method could be to
check the capacity by means of a battery tester, e.g. in connection with a
radio survey.
( IMO Resolution A.702(17), COMSAR/Circ. 16)
Note: - When determining the battery capacity the following must also be
taken into consideration:
• The battery is normally not fully charged;
• Reduction of capacity due to ageing;
• Reduction of capacity due to high or low temperatures; and
• Reduction of capacity due to rapid discharge.
Radio batteries The batteries should be properly marked with type or construction,
rated capacity, and installation date. The marking must be visible when the
batteries have been installed and during their lifetime. A label warning of
explosion danger should be displayed near the installed batteries. Any type or construction of batteries (e.g. lead acid, alkaline,
maintenance free, traction, semi-traction, etc.) may be used as reserve source
or sources of energy, taking into consideration the environmental conditions of
the location where they are installed. The battery should maintain its rated capacity when inclined at any
angle up to 22 ½ degrees in any orientation.
MSIS 27/CH 12/Rev 1017/Page 40 of 46 All battery units must be securely braced so that they will not be
dislocated by movement of the ship. An instruction manual which contains all necessary specifications of
the batteries should be available on board. The information should include at
• capacity and temperature range within which the stated capacity is
maintained for the specific operation period i.e. 1 hour or 6 hours;
• charging voltage and current limits in order to keep batteries fully
charged while preventing overcharging;
• actual specific gravity of the electrolyte and/or cell voltages or the
voltage of the fully charged battery;
• guidelines on how to carry out a controlled discharge test;
• methods of determining the condition of charge of the battery, e.g.
check of specific gravity of electrolyte (acid density) or check of battery
cell voltage/battery voltages by using an accurate measuring
instrument in according with the battery manufacturer’s specifications;
• requirement for ventilation; and
• requirement for maintenance. Equipment requiring a lower voltage than the total voltage of the
battery bank should not be connected to a part of the battery bank. The batteries should be installed in the upper part of the ship, in an
elevated position and as close to the radio equipment as possible. An outdoor located battery case should be avoided due to
considerable temperature variation.
Note: - Ideal location for the radio batteries is in a battery room with a constant
temperature of approx. 20 degrees C. The location should in general satisfy
the manufacturers specifications with regards to temperature tolerance and
environmental strain in accordance with IEC 60945 or other equivalent
standards. Batteries of different types, different cell constructions, different
capacities or different manufacturers should not be mixed in a battery bank. Batteries of different types and different cell construction should not
be installed in the same location if they can affect each other. Sufficient ventilation for batteries should be provided, as required by
the battery manufacturer.
MSIS 27/CH 12/Rev 1017/Page 41 of 46 Electrical installations including battery chargers, located in the
battery room should be intrinsically safe. Sufficient space between batteries or battery banks should be
provided in order to enable inspections and maintenance. The cabling from the batteries should be protected against earthand short-circuits and be appropriately fused and installed according to
recognised international standards (IEC 60092-101 and IEC 60533) . Battery
cables should have sufficient dimensions to prevent voltage reduction at peak
current consumption.
(COMSAR/Circ. 16)
Uninterruptible Power Supplies (UPS)
A UPS is defined as a device which for a specific period of time supplies
continuous power to radio equipment independent of any power failures in the
ship’s main or emergency source of electric energy. The UPS, installed as the
reserve source or sources of energy, should meet the general requirements
set out in Resolution A.694(17), as applicable, and should also comply with
the following requirements:
• Comprise an automatic charger; and
• comprise rechargeable accumulator batteries, complying with the
guidelines regarding accumulator batteries.
• Provisions should be made for an aural alarm and visual indication at
the position from which the ship is normally navigated, indicating any
failure in the UPS which is not monitored by the alarm and indicators
required by the guidelines regarding automatic chargers;
• The UPS should be operational within 5 seconds of switching on; and
• The UPS should be so designed and constructed that it is protected
against damage resulting from disconnecting the batteries or, with the
battery disconnected, short-circuiting the UPS battery connections. If
this protection is provided by electronic means it should automatically
reset following removal of the open or short-circuit conditions.
(COMSAR/Circ. 16)
Note: - If the UPS does not fulfil the requirements in accordance with IMO
Resolution A.702(17), two separate UPS systems should be installed; one for
the basic radio equipment and one for the duplicated equipment. The
capacity of batteries used in UPS systems is normally stated at a discharge
time of 10 hours. When discharging such batteries at shorter time, i.e. 1 hour
in accordance with the GMDSS requirements, it will only be possible to utilise
MSIS 27/CH 12/Rev 1017/Page 42 of 46
approx. 60% of the battery capacity. It is therefore recommended to
dimension such batteries to be one and a half times larger than the total load.
Automatic battery chargers
Automatic chargers for radio batteries should meet the general requirements
set out in IMO Resolution A.694(17) and should also comply with the following
• The charger must be capable of recharging the completely discharged
accumulator batteries to the minimum required capacity within 10
• The charger should be capable of keeping the batteries appropriate
charged as prescribed by the manufacturer for permanent charging;
• The supplied voltage and current should always be within the tolerance
limits prescribed by the battery manufacturer, taking into account the
environmental temperature of the battery, likely to be experienced in
ship. A protection should be provided against over charging or
discharging of batteries from a possible fault in the charger;
• The automatic charger should be provided with a visual indication that
it is switched on. An indication of the battery voltage and
charge/discharge current should be available on the navigation bridge;
• Provisions should be made for an aural alarm and visual indication at
the position from which the ship is normally navigated, indicating when
the charging voltage or current is outside the limits given by the
manufacturer and indicating failure of the mains supply and / or
charger. It should not be possible to disable this alarm and indication
and it should only be possible to acknowledge and silence the alarm
manually. Both the alarm condition and indication should reset
automatically when normal charging condition has been restored.
Failure of the alarm system should not interrupt the charging or
discharging of batteries;
• The automatic charger should be operational within five seconds of
switching on or after a power supply interruption; and
• The automatic charger should be so designed and constructed that it is
protected against damage resulting from disconnection the batteries or,
with the battery disconnected, short-circuiting the battery connection. If
this protection is provided by electronic means it should automatically
reset following removal of the open or short-circuit conditions.
( COMSAR/Circ. 16)
Note: - As said in 12.9.1, it is not advisable to provide the main source of
energy to the GMDSS equipment through the battery charger. However, if the
MSIS 27/CH 12/Rev 1017/Page 43 of 46
battery charger is used to supply parts of the GMDSS installation directly, i.e.
the MF/HF transceiver, the capacity of the charger should be dimensioned for
simultaneous supply of connected equipment and maintaining a sufficient
charging of the batteries.
Protection of circuits for accumulator batteries Battery circuits (i.e. the cables from battery case/room) should be
protected against short-circuit and overload. The protection device is to be
installed as near as possible to the batteries. When conductors from the batteries are not protected against shortcircuit and overload, they are to be installed so as to be proof against short
circuit and earth faults. The requirements for short-circuit protection also apply
to charge current circuits.
Note: - For certain applications it may be necessary to establish measures
which may conflict with these requirements. As an example, screening of
battery cables can be required to avoid electro-magnetic interference, e.g. by
using single-core insulated cables without screening installed in separate
metal pipes which are properly earthed. Special measures should then be
established to reduce the possibility of mechanical damage to the cables. Equivalent solutions may be accepted, e.g. by using doublescreened cables in the battery room with explosion-proof fuses. The inner
screen must be treated according to Ex-rules, but the outer screen can be
treated according to what is necessary to achieve good EMC-screening. The
outer screen can e.g. be earthed at both ends to protect against High
Frequency EMC-fields.
Cabling and wiring
12.10.1 The cabling and wiring in the radio installation should be designed
so as to prevent electrical interference to radio and navigational equipment.
12.10.2 Cables must have the correct dimension to prevent voltage
reduction to radio equipment when full load. The voltage reduction in copper
conductors is calculated as follows:
• Voltage drop = 0,035 x length (m) x total load (A) divided by the cross
section in squared mm).
12.10.3 In order to reduce interference it is essential to have good
separation between signal cables and those cables carrying higher voltages.
12.10.4 All cabling and wiring must be of a type approved and suitable for
use on board ships.
MSIS 27/CH 12/Rev 1017/Page 44 of 46
Battery circuits – fuses and breakers Each radio system should have separate fuses for both AC and DC
voltages to which it is connected. AC and DC fuse boards should be located
on the bridge or in close proximity to the bridge. A single fault in one of the power units must not affect both the
basic and duplicated radio equipment. All fuses and breakers must be clearly marked and labelled to
clearly indicate which equipment is being protected.
Note: - A VHF with DSC, a MF/HF DSC transceiver, a NBDP with printer, and
Inmarsat equipment with a VDU and printer are each considered as a “radio
Equipment for non-Directive Fishing Vessels
Non-Directive fishing vessels are new vessels 12 to 24m length, and existing
vessels of 12 to 45m length.
Sea area
A1 A2
Hand held VHF radio (a)
Fixed VHF radio installation (b)
VHF Channel 70 DSC watch installation (c)
Float-free satellite EPIRB incl. 121.5 MHz homing 1
device (d)
MF radio installation (e)
or 1 1
MF/HF radio installation (f)
or 1 or 1
NAVTEX receiver
INMARSAT enhanced group calling (EGC) receiver
(a) The equipment must be capable of operating on VHF Channel 16 and one
other channel and be of a type specifically designed for operation in survival
craft. In particular, the equipment must be rendered fully waterproof either
through design or use of suitable covers. A spare, fully charged battery must
be available in case of emergency.
(b) The VHF radio installation must be capable of transmitting and receiving
DSC on channel 70, and radiotelephony on channel 6, 13 and 16
(c) This may be combined with the fixed VHF radio installation
(d) The satellite EPIRB must be installed in an easily accessible position
where it can be manually released and placed in a liferaft.
MSIS 27/CH 12/Rev 1017/Page 45 of 46
(e) The MF radio installation must be capable of transmitting and receiving, for
distress and safety purposes, on the frequencies 2187.5 kHz using DSC,
which may be separate from or combined with this equipment, must also be
provided. If an INMARSAT-C or an MF/HF radio installation is fitted on the
fishing vessel, an MF radio installation is not required.
(f) The MF/HF radio installation must be capable of transmitting and receiving,
for distress and safety purposes, on all distress and safety frequencies in the
bands between 1,605 kHz and 4000 kHz and between 4000 kHz and 27,500
kHz using DSC, radio telephony and direct-printing telegraphy (telex). A
facility to maintain DSC watch on 2,187.5 kHz, 8,414.5 kHz and on at least
one of the distress and safety DSC frequencies 4,207.5 kHz, 6,312 kHz,
12,577 kHz or 16,804.5 kHz must also be provided.
MSIS 27/CH 12/Rev 1017/Page 46 of 46
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