IMO HARMONIZATION OF GMDSS REQUIREMENTS FOR RADIO INSTALLATIONS ON BOARD SOLAS SHIPS. Submitted by Germany

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1 INTERNATIONAL MARITIME ORGANIZATION E IMO SUB-COMMITTEE ON RADIOCOMMUNICATIONS AND SEARCH AND RESCUE 7th session Agenda item 17 COMSAR 7/17/1 10 October 2002 Original: ENGLISH HARMONIZATION OF GMDSS REQUIREMENTS FOR RADIO INSTALLATIONS ON BOARD SOLAS SHIPS Submitted by Germany Executive summary: Action to be taken: See paragraph 4 Related documents: SUMMARY A harmonized installation guidance is essential for proper operation of GMDSS equipment. The attached document describes installation parameters for radio equipment on board SOLAS ships. MSC 71/23, paragraph 20.23, MSC 75/24/Add.1, annex 29, L.1, COMSAR 6/22, paragraph 18.2 Introduction 1 The Maritime Safety Committee, at its seventy-first session, decided to include this subject as a new agenda item on the work programme of the Sub-Committee, because it became obvious that there are differing interpretations of chapter IV with regard to technical installation of GMDSS radio equipment. 2 Several Administrations have already published national guidelines for the installation of GMDSS radio equipment on board their SOLAS ships. After the subject has been discussed in several fora, Germany supports the development of harmonized installation guidelines. 3 It is the opinion of Germany that the attached guidelines could form a basis for discussion in the Sub-Committee. Carriage requirements detailed in chapter IV are not included. The draft is focussing on technical installation issues. Action requested of the Sub-Committee 4 The Sub-Committee is invited to consider the attached draft guidelines as a contribution for deliberations on the development of an appropriate proposal for the submission to the Maritime Safety Committee. *** For reasons of economy, this document is printed in a limited number. Delegates are kindly asked to bring their copies to meetings and not to request additional copies.

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3 PROPOSED DRAFT GUIDELINES GMDSS requirements for radio installations on board SOLAS ships 1 General Normative references Radio equipment and installation requirements Documentation List of required documentation Antenna drawings Radio arrangement drawings Marking and notices Emergency lights Connections of Navigational sensors GNSS Receiver Heading sensor Location of radio equipment General Fixed radio equipment Bridge arrangement VHF Transceivers and VHF DSC Controllers Watch-keeping receivers for DSC MF/HF telex NAVTEX and EGC receivers Satellite communication systems Distress panel on passenger ships Two way radiotelephone (VHF Hand Helds) Float-free satellite EPIRBs Radar transponders (SART) Aeronautical VHF transceivers Voluntary radio equipment Antenna installation General Antenna design for mandatory radio equipment Marking General requirements for locations Cabling VHF antennas MF/HF antennas...12

4 Page Satellite antennas Inmarsat-C antenna Inmarsat-B antenna GNSS antennas on board passenger ships Antennas for voluntary radio equipment Power supply Sources of energy Radio Batteries Cabling Screening and earthing Screening Earthing...16

5 Page 3 1 General 1.1 Normative references The guidelines are worked out in accordance with the following conventions, regulations, instructions and guidelines: SOLAS 2001(i.e. SOLAS 1974 as amended later) IMO Resolutions (Performance standards) IMO Circulars ITU Radio Regulations (RR) 1.2 Radio equipment and installation requirements Radio equipment installed on a ship shall meet the relevant IMO requirements and ITU recommendations and shall be of a type approved by the administration. 1.3 Documentation List of required documentation For the radio installation the following information shall be carried on board: Operation and installation manuals Service documentation Battery capacity calculations Antenna drawing Wiring diagram For the installation radio equipment the following information shall be submitted: List of equipment Battery capacity calculations Antenna drawing Radio arrangement drawing Wiring diagram. For new buildings the antenna- and radio arrangement drawings should at least be of size 1 : 50. Approved wiring diagram, radio arrangement as well as antenna drawings shall be kept available on board the ship Antenna drawings Antenna drawings should show all antennas seen from fore or aft position, the port or starboard position and from above. This applies to the following antennas:

6 Page 4 All transmitting antennas including location of antenna turner All receiving antennas including GNSS antennas Radar antennas Satellite communications antennas Radio arrangement drawings These drawings should show the location of the following equipment: Controllers for transmitting distress alarm VHF radio installations, including any control units MF or MF/HF installations, including any control units, telex printer etc. Satellite communication equipment, including terminals, printers etc. Watch-keeping receivers for VHF Ch. 70, MF 2187,5 khz, and HF distress channels in 4, 6, 8, 12 and 16 MHz bands NAVTEX and EGC receivers EPIRBs and Radar transponders Two-way VHF radiotelephone apparatus and their chargers Emergency light powered from a reserve source of energy to illuminate the mandatory radio equipment Reserve source of energy (radio batteries) and charger Fuse box Wiring diagram These drawings should show the following connections etc: Antenna connections Connections to ship s main and emergency source of energy, to the reserve source of energy and switching systems for all radio- and radio navigation equipment, both for mandatory and voluntary radio equipment Connection of radio equipment to different sources of energy UPS with all connections, if installed, for mandatory radio equipment. Block diagram showing the operation scheme and the switch over to alternative power supplies Battery chargers Fuses for all radio equipment Connections between GMDSS equipment and GNSS systems. 1.4 Marking and notices All radio equipment shall be duly marked with type designation and approval marking. The marking shall be clearly visible when the equipment has been installed. The radio installation shall be duly marked with the ships call sign, the ships station identity and other codes applicable for the of use of the radio equipment.

7 Page 5 DSC operation procedures shall be posted near the DSC equipment on the navigating bridge. Emergency procedures for VHF Ch. 16 shall be posted near the relevant equipment on the bridge. IMO`s GMDSS operating guidance for masters of ships in distress situations and the procedure False alerts shall be posted on the navigation bridge. 1.5 Emergency lights All mandatory radio equipment shall have reliable emergency lightening, independent of the main and emergency sources of electrical power, i.e. powered form a reserve source of energy, which normally is the radio battery. This light shall give adequate illumination of the controls for safe operating of the radio equipment, and the working table for reading and writing. Means should be provided for dimming any light source on the equipment that is capable of interfering with navigation, i.e. by adjustable light or 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 by used. Scale illumination (powered from a reserve source of energy) may be 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. Each emergency light shall have its own circuit and fuse. 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 shall be properly marked. 1.6 Connections of Navigational sensors GNSS Receiver A GNSS receiver shall 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. This GNSS receiver shall (similar to the mandatory GMDSS equipment) also be supplied from the reserve source of energy/batteries Heading sensor If the GMDSS satellite equipment requires automatic antenna adjustment according to ships heading, the heading sensor (GYRO) shall be connected. In this case the GYRO shall also be supplied with energy from the reserve source of energy/batteries.

8 Page 6 2 Location of radio equipment 2.1 General 2.2 Fixed radio equipment Bridge arrangement Radio work station The radio operator s working place ( radio work station ) is the place where the radio equipment is located except equipment to be installed at the conning position and operated. The radio work station should be located on the navigation bridge as close as possible to the place from which the ship is normally navigated (conning position) and should not be located in a separate room. From the radio work station the navigator should have an over all view of navigation while operating the radio equipment. Means are to be taken that noise or incoming light does not affect the operation of the radio station. From the radio operator s working place it should be possible to control all mandatory radio equipment except the equipment installed in the manoeuvring console. It should be also possible to control the battery charger and the fuses from this place. A table of a minimum width of 40 cm and a chair in front of the radio control units and monitors shall enable the operator to write down necessary notes or information. The working place and all mandatory equipment shall be illuminated by sufficient daylight and during darkness by reliable electrical light to give adequate illumination of controls for safe operation. The electrical light shall be powered by the reserve source of energy. Means should be provided for dimming any light source on the equipment, which is capable of interfering the navigation; in addition a curtain is required Mandatory radio equipment All mandatory radio equipment as well as battery chargers and fuse boxes except VHF control units and NAVTEX receiver should be installed at a radio work station on the navigation bridge. Watch receivers may alternatively be located elsewhere on the navigating bridge. Incoming audible alarms and indications (DSC, EGC or NAVTEX ) shall be clearly recognised from every position on the navigation bridge. If GMDSS radio equipment is installed in a separate room (e.g. communication office) it should be possible to activate distress alarms remote controlled on the appropriate frequencies and conduct distress traffic from the bridge Remote controlled radio equipment For both the basic equipment and the duplication it shall be possible to operate all apparatus from its own control unit. In addition remote controlled units may be installed in an appropriate

9 Page 7 position on the bridge. If remote controlled units are installed in the manoeuvring console or in the reach of the position from which the ship is normally navigated, these control units shall take priority VHF Transceivers and VHF DSC Controllers VHF with DSC forming part of the mandatory VHF communication equipment for safety of navigation shall be located in 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 shall be possible to transmit DSC distress alarm from the conning position. 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. In order to conduct power measurements, easy access to the antenna output of each equipment shall be provided. MF/HF transceivers With mandatory equipment it should be possible to activate the distress alarm from the navigation bridge. If the equipment can be remote operated from other units, priority shall be given to the unit on the navigation bridge. DSC on MF is required in sea areas A2, A3 and A4, irrespective of selected radio equipment solution. It shall therefore always be possible to activate the DSC distress alarm on 2187,5 khz from the navigation bridge. If combined MF/HF radio equipment is chosen as mandatory GMDSS equipment, it shall also be possible to activate the distress alarm from the navigating bridge on the mandatory HF DSC frequencies. RF power amplifiers shall not be located in the navigation bridge area. Location in such an area may, however, be accepted if it can be granted that the EMC-directive requirements are fulfilled. The antenna tuner shall be located in an outdoor position below and close to the antenna. If the transmitter antenna is not permanently connected to the transmitter, it should be automatically connected when the alarm signal is transmitted. (See also subsection 0 regarding MF/HF antennas.) Watch-keeping receivers for DSC The watch receiver for VHF DSC channel 70, MF DSC 2178,5 khz and HF DSC scanning receiver should be located so that the alarm is clearly audible all over the navigation bridge. Alternatively, additional alarms should be installed. It should be possible to read the DSC alarm messages on the navigation bridge.

10 Page 8 Easy access to the antenna connector should be possible in order to conduct test of the equipment by means of measuring instruments. The watch receivers should not be muted or interrupted when other radio equipment is being used. If a scanning receiver is used, this receiver should not scan other frequencies than the MF DSC distress frequency and the HF DSC distress and safety frequencies. If it is required to keep watch on other DSC frequencies than those for distress and safety, an extra scanning receiver shall be installed MF/HF telex Telex selcall number or MMSI number shall be displayed near the terminal NAVTEX and EGC receivers The NAVTEX and EGC receivers should be installed on the ship s navigation bridge in a location clearly visible and easily accessible for the navigators. If an external printer is part of the NAVTEX receiver this printer should be located close to the receiver and clearly visible. The NAVTEX receiver shall be connected to a dedicated antenna that shall not be used for any other purposes. The NAVTEX equipment may be combined with weather facsimile, provided NAVTEX messages are not lost when the equipment is used as weather facsimile, NAVTEX messages with message format B3=00 or B2=A, B, D or L, (priority messages) are always be printed out immediately after they are received. The EGC receiver may be combined with an Inmarsat SES Satellite communication systems If the ship earth station is the main or duplicated equipment, it should be possible to activate the distress alarm from the conning position and to conduct follow-up distress communication from the radio workstation on the navigating bridge. If the mandatory Inmarsat terminal is connected to other equipment as e.g. the ship s PC-network or an external data terminal, all mandatory GMDSS requirements in accordance with SOLAS shall always be fulfilled. In this case the printer should be connected 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.

11 Page Distress panel on passenger ships On passenger ships the distress unit and the distress alarm unit or a combination of both should be installed in the manoeuvring console easy accessible for navigators from the position from which the ship is normally navigated. The panel shall give a clear visual indication whenever any button or buttons have been pressed. Means shall be provided to prevent inadvertent activation of the button or buttons (e.g. by use of a spring loaded lid or cover permanently attached by hinges in order to fulfil the requirement of carrying out at least two independent actions when transmitting distress alert). The distress panel shall provide visual and aural indication of any distress alert or alerts received on board and shall also indicate through which radio communication service the distress alerts have been received. Incoming alarms should be visible from the place from which the ship is normally navigated. The audible alarms should be well audible on the bridge. The possibility to switch off the audible alarm manually should be provided. If the bridge of a passenger ship is too narrow for the installation of the above mentioned units those units may be installed at any other location or replaced by the required DSC controller if this is easily to be reached by the navigator. 2.3 Two way radiotelephone (VHF Hand Helds) The two-way VHF radiotelephone apparatus and required batteries should be located on a dedicated place on the navigation bridge where they are clearly visible and easy accessible for the navigators. If VHF radiotelephones are placed in a cabinet, the door of the cabinet should not be locked by key. The cabinet s door should be clearly marked with an appropriate standardised label. 2.4 Float-free satellite EPIRBs The location for a satellite EPIRB shall give a high reliability that the EPIRB can float free and avoid being caught in railings, superstructures etc, if the ship sinks. The EPIRB shall be located so that it may easily released manually and brought to a survival craft by a person. If the installed satellite EPIRB is used as the secondary (mandatory) means of distress alerting, it shall not be located in a position which can be reached by a vertical ladder only. The installation place should be on the same deck as the wheel house close to one of it s entrance doors with easy access to the EPIRB. A location on compass deck may be accepted if accessible by stairs; or it should be possible to activate the EPIRB remotely from the bridge; in this case the EPIRB should be installed so that it has unobstructed hemispherical line of sight to the satellites; or an additional EPIRB is installed on the navigation bridge.

12 Page 10 The float-free EPIRB shall be permanently marked (sea water resistant marked) with the ship s call sign, serial number of EPIRB, MMSI number, date of service/periodical maintenance and expiry date of battery and hydrostatic release mechanism as applicable. The EPIRB should be equipped with a buoyant lanyard suitable for use a tether to life raft etc. Such buoyant lanyard should be so arranged as to prevent its being trapped in the ship s structure. 2.5 Radar transponders (SART) The radar transponders shall be placed in brackets on both sides of the ship and preferably visible from the navigation bridge. It should be easy to bring the transponders to the lifeboats or liferafts. Alternatively, they may be placed in brackets in covered lifeboats if such location permits rapidly replacing of the SARTs into any survival crafts which may be used in emergency situations. On ships carrying at least two SARTs and equipped with free fall lifeboats, one of the SARTs shall be installed in the free fall lifeboat. In any case one SART has to be installed in the vicinity of the navigation bridge. The SARTs shall have waterproof marking with the ship s name and callsign and expiry date of the battery. 2.6 Aeronautical VHF transceivers All passenger ships shall be provided with means for two-way on-scene radiocommunication for search and rescue purposes using the aeronautical frequencies 121,5 MHz and 123,1 MHz from the Navigation Bridge. Portable Aeronautical VHF transceivers and required batteries should be located on a dedicated place on the navigation bridge where they are clearly visible and easy accessible for the navigators. If they are placed in a cabinet, the door of the cabinet should not be locked by key. The cabinet s door should be clearly marked with an appropriate standardised label. 2.7 Voluntary radio equipment Additional, voluntarily carried Non-GMDSS radio equipment like e.g. Mobile telephone Radio amateur stations Inmarsat Mini M May be installed on the bridge provided that EMC requirements are fulfilled and navigation and radio communication is not degraded Operation of such equipment is at the discretion of the master

13 Page 11 It is not advisable to locate the equipment in front of the navigation bridge, on the map table, close to the conning position, or close to radar and ARPA equipment. It may be placed at the radio work station. 3 Antenna installation 3.1 General Antenna design for mandatory radio equipment For the mandatory radio- and radio navigation facilities, suitable antennas have to be installed. If a special antenna prescribed by the maker of the equipment, this antenna should be used Marking The antenna connection box should be marked with the type of connected equipment General requirements for locations Attention should be paid to the location of all but specially of mandatory antennas in order to obtain best possible efficiency and in order to avoid the reducing of radio equipment performance. Transmitting antennas and antennas exclusively for receiving should be separated as far as possible Cabling For connections between radio facilities and antenna or antenna connector boxes, coaxial cables should be used. For these connections, the cables prescribed by the maker of the radio equipment should be used. Coaxial cables should be installed in separate signal cable channels/tubes and at least 10 cm away from power supply cables. Crossing of cables should be done at 90 angles. The coaxial cables should not be exposed to sharp turns that may lead to change in the characteristic impedance of the cable. The following guidelines should apply with regards to accepted bending radius of coaxial cables: Permanent installation (one bending): 5 times the cable's outside cable diameter. Flexible use: 20 times the outside cable diameter. 3.2 VHF antennas VHF antennas should be installed vertically polarized and, as far as practicable, be omnidirectional in the horizontal plane.

14 Page 12 The installation should be suitable for efficient radiation and reception of signals. The shortest possible length of cable way and a low-loss coaxial cable has to be used in order reduce signal loss. The distance in horizontal direction from conductive materials should be 2 metres minimum. The distance between two VHF antennas, located on the same level, should be at least 5 metres. Otherwise the minimum distance should be at least 1 metre. For each DSC receiver a separate antenna should be installed on the best possible location on board. The output power should be between 6 and 25 Watt (with reduction between 0.1 and 1 Watt). The reflected power shall be max. 10% of the measured output power. 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. The 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. 3.3 MF/HF antennas The antenna mounting arrangement or pedestal should be constructed so to withstand the strain from swaying and vibration. Attention should be paid to self-supportive vertical antennas and their swaying radius (stated by the manufacturer). The minimum length of the antenna should be 9 metres. Antennas shall be located in a position which is elevated and as free as possible. In order to obtain the best possible efficiency it should not be installed close to constructions made by conductive materials. Wire-antennas shall be protected against breakage. Self-supportive vertical antennas should be installed in an angle of 3-5 degrees inclined rearward to avoid harmful vibrations. The antenna tuning unit shall be located outdoor and as close at possible to the antenna. The ATU should be easily accessible for service purposes. The ATU, the antenna and the wire to the antenna shall be protected against accidental touch. The transmitting antenna should have an insulation resistance to earth of more than 50 MΏ in dry weather and of no less than 5 MΏ in humid weather if the transmitter is de-connected.

15 Page 13 The DSC-watch receiving antenna shall be located as far away as possible from the transmitting antennas for MF/HF in order to avoid blocking of the watch receiver. The NAVTEX antenna shall be located as far away as possible from the transmitting antennas for MF/HF in order to avoid interference. Active antennas are permitted, provided the power supply is the same as for the NAVTEX receiver. 3.4 Satellite antennas Ensure that the antenna place is outside the beam of S-band radar antennas (plus/minus 10 degrees in vertical direction). The antennas should be easily accessible for service purposes and so located, that no heat and heavy quantities of funnel smoke penetrate the antenna Inmarsat-C antenna The antenna should be located primarily at the top of the mast in such position that no objects or constructions down to 15 degrees below the horizon are degrading the performance of the equipment. In the direction for and aft this angle may be reduced to 5 degrees below the horizon. Are obstructions in this area unavoidable, the shadow sector should not be greater than 2 degrees. To fulfil this recommendation, the distance to the obstruction should be 25 times the diameter of the obstruction Inmarsat-B antenna The antenna should be located on a pedestal or mast on the top deck. The pedestal/should should be constructed so, that vibrations are reduced as much as possible. The resonance frequencies of mast/pedestal and of the antenna should not be identical. The antenna should be located in such position that no objects or constructions down to 5 degrees below the horizon are degrading the performance of the equipment. Preferably, all obstructions within 3 m of the antenna should be avoided. Obstructions less than 15 cm in diameter can be ignored beyond this distance. Are larger obstructions in this area unavoidable, the shadow sector should not be greater than 6 degrees. To fulfil this recommendation, the distance to the obstruction should be 10 times the diameter of the obstruction. Antennas should not be installed closer than 5 m from the passenger area. However, no restrictions are required when the antenna radome is installed at least 2 m above the highest point accessible to passengers GNSS antennas on board passenger ships The antenna should be placed outside the beam path of transmitting radar and Inmarsat Satcom (A, B, C or M). The GNSS antenna should be mounted below and at least 5 m away from these types of antennas, and not to be placed within 3 m of a SSB- or VHF transmitting antenna.

16 Page Antennas for voluntary radio equipment Antennas for voluntary radio equipment may be located on deck, provided its use does not interfere with antennas 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. 4 Power supply 4.1 Sources of energy All the basic and duplicated equipment shall be supplied independently and directly by the main source of electrical power, the emergency source of electrical power (if applicable) and a reserve source of energy. The distribution of supplies shall be independent of those for other equipment and be sited on the navigation bridge or other suitable position on the bridge deck. Facilities shall be provided for manual or automatic changing over between the main source and the emergency source of energy. The change-over from the ships main or emergency source of energy to the reserve source of energy should be done automatically or manually in such way that both the basic and the duplicated equipment (if installed) will be connected simultaneously. If change-over is done by a manual switch, this switch shall be visible, easily accessible and properly marked. Each consumer should be individually connected to the distribution panel bus bar and individually provided with short circuit protection; all fuses and breakers should be clearly marked with the consumers connected. Any fault in the reserve source of energy or the battery charger should not impair or reduce the functional availability of the GMDSS equipment while energised from the ship's supply. Alarms activated by ship s main or emergency source of energy failure or fail of the battery charger for the reserve source of energy should be audibly on the bridge in the position from which the ship is normally navigated. The appropriate optical indication may be displayed at the power supply console. 4.2 Radio batteries Batteries, if they are used as reserve source of energy, should not be a mixture of different types, different capacities or different age. Consumers should not be connected to a part of the battery bank.

17 Page 15 Radio batteries should be located in the upper part of the ship and as close to the radio equipment as possible. All battery units should be securely braced. Batteries should be installed in such a manner that they are readily accessible for inspection, maintenance and replacement and that equipment cannot be damaged by exhausted gases or leaked-out electrolytes. All battery rooms and battery boxes should be properly ventilated. Battery boxes should be protected against corrosion and the ingress of seawater. Where batteries are located on shelves in a locker room there should be a minimum of 300 mm free space above each unit. Battery cabinets and boxes should not be located in the accommodation. A label should be affixed to each battery unit, which clearly indicates its make, type, voltage, capacity, and date of installation. 4.3 Cabling The cabling and wiring in the radio installation shall be designed so as to prevent electrical interference to radio and navigational equipment. Cables should have the correct dimensions to prevent inadvertent voltage reduction to radio equipment when on full load. In order to reduce interference in is essential to have good separation between signal cables and those cables carrying higher voltages. All cabling and wiring should be of a type suitable for use on board ships. 5 Screening and earthing 5.1 Screening Coaxial down leads should 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 should be screened and the screen properly earthed or the cable has to be installed in a metal tube or duct. In order to avoid interference from electromagnetic noise it is essential that EMC and manufacturers guidelines relating to screening and earthing are correctly followed.

18 Page Earthing Each unit of radio equipment should have a separate earth connection. MF/HF antenna tuners should be earthed with either a copper bar or a copper band. The earthing bar or strap should be as short as possible, should not be more than one metre in length and should be at least 60 mm in width. Copper bars and straps should be soldered to the steel bulkhead. 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 vessels. Reference should be made to appropriate guidelines for Earthing in Maritime Installations.