IEC 945 was originally produced to give test methods and, where appropriate, limit values to the IMO Resolution A.574(14) which was a recommendation on general requirements for electronic navigational aids. (It has subsequently been replaced, see below.) The tests dealing with electromagnetic immunity could not be produced in time for the publication of the original standard, and these were added later in 1992 as amendment 1. In 1991 the IMO, when discussing the changes that would arise with the introduction of the global maritime distress and safety system (GMDSS), noted that in future, radio equipment would be installed on the bridge of a vessel alongside the navigation equipment instead of in a special radio room as hitherto. The IMO consequently withdrew Resolution A.574(14), and a corresponding Resolution A.569(14) dealing with the general requirements of radio equipment, and replaced them with IMO Resolution A.694(17). A second edition of IEC 945 was rapidly prepared to reflect this change. The third edition of IEC 945 in 1996 was a complete revision which aligned the test methods with appropriate other IEC standards and introduced, wherever possible, the requirements of the classification societies. The scope was extended to make the standard applicable additionally to other equipment installed on and around the bridge of a ship with regard to EMC. A new class of equipment – “portable” – was added, together with better definitions of operational tests which involve subjective judgement and descriptions of operational and durability aspects of software.
This fourth edition (now IEC 60945) extends the detail of operational tests particularly for equipment which is operated through software menus. This has been derived from an exhaustive investigation of appropriate references as described in the Bibliography. The layout of clause 4 (Minimum performance requirements) has been changed to give a better grouping of ergonomics, hardware and software requirements. The EMC tests have been revised with the frequency range having been extended from 1 GHz to 2 GHz. Clarifications to the text of the third edition have been added where experience has shown a need and the references have been updated. A comparison of the test requirements in the third and fourth editions is given in annex G to assist manufacturers and test houses in the use of the new edition.
For centuries, mariners have relied on paper charts to navigate the world’s oceans and waterways. Although adequate, this method does not utilize the latest technology available. Industry experts have determined that computer-based charting systems increase the safety and maximize the efficiency associated with navigation. To take advantage of these benefits, the International Maritime Organization (IMO) now allows chart carriage requirements to be satisfied through electronic means.
Consisting of electronic charts, software, and hardware (such as a computer, monitor, and I/O devices), Electronic Chart Information and Display Systems (ECDIS) are becoming increasingly prevalent in the marine industry. In the early 2000s, the IMO adopted ECDIS standards that electronic navigation systems must pass to be approved as a primary means of navigation. All ECDIS providers must ensure that hardware is designed to operate in a marine environment and satisfy IEC-60945, a standard for maritime navigation and radio communication equipment and systems.
The IEC-60945 specification has four different product categories, depending upon the equipment’s location on board a ship, the: portable, protected, exposed, and submerged. For the purposes of an ECDIS system, the equipment is typically used on the bridge of a ship, which falls under the protected category. Test requirements for the protected category of the IEC-60945 specification include environmental, safety, and EMC parameters, as follows:
|Dry heat||55℃/131℉, operational test|
|Damp heat||40℃/104℉@93% relative humidity, operational test|
|Low temperature||-15℃/5℉, operational test|
|Vibration||2Hz-100Hz, operational test to simulate propeller vibration and wave slamming|
|Corrosion||Salt mist exposure, non-operational, 28 day total test|
|Acoustic noise||60dBA @1m to measure noise levels that may disturb bridge operations|
|Protection againstAccidental access to dangerous voltages||Limited access to high voltages within the chassis|
|Radiated emissions||Electromagnetic radiation from the chassis or cables that may interfere with other devices nearby|
|Conducted emissions||Electrical noise conducted from the chassis on power cables that may interfere with equipment connected to the same power supply|
|Radiated susceptibility||Immunity to electromagnetic radiation from other devices|
|Conducted susceptibility||Immunity to electrical noise on power lines|
|Electrostatic discharge||Immunity to 6000 yolt contact discharge and 8000 yolt air discharge|
|Compass safe distance||Magnetic field radiation that may interfere with compass operations|
Several design elements must be taken into account to produce an instrument that meets the IEC-60945 requirements listed above, including:
• Masking, or other techniques associated with the protective coatings, to allow for electrically conductive surfaces on cover or door flanges, thereby preventing electromagnetic radiation from entering or escaping the enclosure
• Using stainless steel fasteners, latches, hinges, and other hardware
• Designing the structure of the device to limit chassis resonances induced by external vibration
• Selecting computer components rated for the temperature and humidity levels required
• Choosing OEM components with long lifecycle status due to the substantial logistical issues of scheduling, performing, and passing the EMC and Environmental tests