Approaches to Rotterdam will benefit from eDLoran

As ecdis technology is advanced, more functions, features and capabilities are added by manufacturers. However, it is probably premature to consider the concept of advanced ecdis in global terms when the majority of the ships at sea still have to make a safe, effective transition from paper charts. And when many officers and masters will be faced with repeated ecdis familiarisation exercises as they move between vessels equipped with different makes and models of ecdis, will they have the time and inclination to explore additional features and capabilities?

The situation may be different for personnel on long-term contracts with companies that have a coherent ecdis equipment policy, but these lucky individuals will be in the minority.

There are certainly advances in ecdis as established manufacturers bring out new or revised models, and new entrants claim that their product designs benefit from addressing issues raised by early ecdis adopters. Nonetheless, successful ecdis operation can be well served by using the core functions and utilising external factors, such as sensor inputs and training.

For example, manufacturers, trainers and those who have made themselves well informed, are clear that ecdis does not rely on global navigation satellite systems (GNSS) – GPS and Glonass – for its successful operation. Ecdis has the capacity to act as a platform for traditional chart work, although this is not always as straightforward as might be thought desirable.

Ecdis also has the capacity to provide very accurate dead reckoning and estimated positions. At a recent open day held at its Enav centre in Southampton, UK, Ecdis Ltd managing director Mark Broster presented a live demonstration on the use of ecdis without GPS in the company’s full mission simulator.

But regardless of these capabilities, it is apparent that in many people’s eyes ecdis and GPS go hand in hand, so GPS outages can cause problems and anxiety on the bridge. It is also true that even on ships navigating with paper charts, the primary means of position fixing is often simply plotting latitude and longitude co-ordinates lifted from a GPS display.

The steps being taken to provide viable back-up electronic systems to provide redundancy for GNSS are important elements for ensuring the successful industry changeover to navigation by ecdis, and it is no surprise to learn that Rotterdam, one of the world’s largest ports, is taking proactive steps to guard against the risks posed by problems with GPS.

The port has introduced a new system, eDLoran, employing signals transmitted from England, France and Germany, to determine a ship’s position with an accuracy of better than 5m (Marine Electronics & Communications, April/May 2014). It helps pilots to guide vessels precisely along narrow channels to their berths.

The Rotterdam system is complementary to the eLoran technology pioneered by the General Lighthouse Authorities (GLAs) of the UK and Ireland. Both systems ensure that satellite navigation signals are constantly cross-checked against a high-precision aid that will take over automatically if GPS is disturbed, ensuring the continuity of vital navigation data.

The adoption of eDLoran will aid safe navigation in the port, even when GPS fails, said Wim van Buuren, a licensed maritime pilot with the Dutch Pilots’ Association. “Thorough investigation into our aim of improving port accessibility has made us aware of the vulnerability of satellite navigation systems,” he explained.

“Since the accessibility of the highly important Eurochannel in the approach to Rotterdam is maximised by using modern techniques, such as probabilistic tidal window calculations in combination with space-based augmentation systems (SBAS), we need an answer to safeguard navigation when GPS fails.

“Traditional, non-electronic position fixing devices cannot replace SBAS GPS in the shallow North Sea area around Rotterdam. eDLoran is at present known and demonstrated by us as the most successful and most accurate operational navigation system at sea that meets our backup requirements. eDLoran can be implemented at any location where the Loran signal can be received.”

Martin Bransby, research and radionavigation manager at GLAs, said that eLoran is increasingly being accepted as a requisite to shipping safety around the world. However, the future of the system in Europe is dependent on the continued availability of French Loran transmitters and their development to provide eLoran.

“A decision to close down the Loran stations would remove the only practical option for a backup to GPS in the near future, and would deny many opportunities for advancement in the economies of France and neighbouring countries,” Mr Bransby said. “The need for collaboration is paramount in securing the future safety of our ships and in mitigating the threat posed to critical national infrastructures around the world.”

Other nations have committed to eLoran technology. They include South Korea and Russia – which is working with the UK to improve shipping safety along the new high Arctic routes – and the US, where a bill in Congress encourages the development of the new technologies by re-equipping old Loran C facilities.

The risks inherent in reliance on GPS and other GNSS were demonstrated when Russian satellite navigation system Glonass suffered major disruption on 2 April 2014, with all of the satellites in the constellation reportedly producing corrupted information for almost 12 hours.

Readings from GLAs’ Glonass receiver in Harwich, UK, showed location errors of up to 55km off the UK coastline. GLAs research director Nick Ward said: “We have known for a long time that satellite navigation systems are vulnerable to interference and this event demonstrates just how dangerous a failure can be. Our data shows that, during the prolonged disruption, Glonass was providing location data up to 55km out off the UK coast.

“The potential implications of such failures are severe. A vessel travelling in coastal waters, for example, could face vastly increased chances of grounding or collision, and ultimately loss of lives and cargo, as well as pollution. Such a problem could occur with GPS, the EU’s Galileo, or any other GNSS without any warning.” MEC