There are promising complementary technologies that could offer greater resilience, accuracy, integrity and availability of navigation information to mariners. There are devices that can integrate a mixture of diverse inputs that could enhance the use of ecdis for safer navigation.
The Royal Institute of Navigation (RIN) recently highlighted several technologies that could provide ship position alternatives to using the Global Navigation Satellite System (GNSS) constellations. GNSS consists of the Global Positioning System (GPS), Russia’s Glonass and Beidou, a local Chinese service. This will be supplemented with the EU-funded Galileo system later this year when the first commercial operations commence. But although more GNSS satellites will become available, there will still be the need for alternative positioning services.
The RIN believes alternatives, such as inertial sensors, should be considered for future navigation. An inertial navigation system has motion and rotation sensors that continuously calculate the position, orientation and velocity of a ship using dead reckoning. An inertial guidance instrument would have accelerometers and gyroscopes that delivered orientation and position data to ecdis.
IXBlue presented its inertial navigation system at the European Dynamic Positioning Conference in London in February. Product line manager Pierre-Yves Morvan said this instrument could supplement GNSS data to improve reliability of a vessel’s position. In navigation, dead reckoning is the process of calculating a ship’s position based on a previously determined position, then advancing that using known speed, time and course data. The process is subject to cumulative errors, but can be used as a back-up to GNSS.
Other complementary technology for dead reckoning and position fixing include a ranging mode from medium frequency coastal differential GPS beacons and absolute positioning using a ship’s radar. This involves radar securing an absolute position using coastal infrastructure of active radar responders, adapted radar beacons, or passive contour features. Another alternative would be triangulation using signals of opportunity, of which an amplitude modulated (AM) broadcast would be best. The RIN also highlighted how digital television could be used, but its range is limited. Bathymetric seabed contour navigation and using Doppler signals could also be used. Techniques of the future could incorporate quantum technologies that use cold atom sensing of rotation and acceleration.
As ships become more digitally connected, mariners could use more commercial electronics as aids to navigation. The RIN highlighted how digitally aware mariners could use tablet computers, mobile smart phones and other portable devices for vessel positioning and navigation. The RIN considers this to be an issue that may impact safety if seafarers use unapproved equipment. It thinks the risks are exacerbated by the lengthy time IMO takes to prepare regulations enabling and approving new technology. It is for this reason that the shipping industry is slow to adopt new technology and ideas.
When the industry does adopt technology, systems should be designed for mariners to use on a daily basis. Equipment needs to take account of human factors during development, which the RIN said has not been achieved during the development of ecdis. The institute also highlighted the point that seafarers need to be more aware of the limitations of technology. This would be helped if equipment displayed the uncertainty in the measurement of the ship’s position. The RIN also called for more standardisation of ecdis equipment that is driving the need for type-specific training. It has called on IMO to consider introducing a standard mode to ecdis to reduce uncertainties and improve the usability of these devices.
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