This year, the maritime industry witnessed an important milestone in safety and situational awareness at sea, with the introduction of an ADMIRALTY high-density contour Electronic Navigational Chart (HD-ENC) for the UK’s Bristol Channel.
Supported by recent advancements in big data technologies and a wealth of marine geospatial data collected and stored by the UK Hydrographic Office (UKHO), these sophisticated charts support navigation through shallow water by displaying depth contours at one-meter intervals, allowing ECDIS to set safety contours at corresponding levels and with more granularity than has been previously seen with other charts.
As they continue to spread, these advancements in digital navigation are likely to unlock economic benefits for many ports around the world, and have a profound impact on the safety of crews and cargoes.
The journey from paper to digital
When nautical charts were transferred from paper to digital, many of the best practice cartographic standards for creating clear, demarcated visual guides in paper chart production were adopted “as is.” At the time, this was an obvious transition – giving mariners certainty and familiarity whilst learning new passage planning processes.
However, adopting paper chart standards for drawing contours in an electronic navigational chart (ENC) does not realize the full safety benefits of the ECDIS.
In an ECDIS the mariner sets his safety contour value, which corresponds to his under keel clearance. The safety contour in ECDIS is a clear boundary between what is deemed to be safe water and areas that are too shallow to guarantee passage for that ship. Based on the mariner safety contour input and the ENC data available, the system will choose the deepest contour interval that is closest to the mariner setting.
For example, a vessel that sets a safety contour of 13 meters may find an ECDIS defaulting to 20 meter contours, putting seven meters of safe, navigable water ‘out of bounds’ for maneuvering, with the system sounding an alarm to help prevent groundings when none is needed.
For vessels using ECDIS, this means that a clear route – that is, a route that can be safely navigated given the characteristics of a particular vessel – could be displayed as potentially out of bounds or a very narrow passage. Even more challenging is that this could lead to mariners knowingly crossing safety contour to reach their destination, with all the clear safety ramifications that this possesses.
An example of this in practice is “The Bridge” in the UK’s Bristol Channel. In this area, silt collects on the seabed to form an area that is markedly shallower than the rest of the Channel. All manner of vessels must pass over this shallower ground to get to the Port of Bristol – one of South West England’s most important trading ports – or continue on to Gloucester.
Despite being safe to transit, this area falls beyond the safety contour for most ships. This means that mariners entering the Port of Bristol have to knowingly cross the contour, which sets off multiple alarms, causes major disruption and creates significant paperwork that the master must subsequently explain.
Supporting navigational safety through ADMIRALTY HD-ENCs
To help overcome this, the UK Hydrographic Office (UKHO) has started to use automated contouring processes to produce ENC data of areas where there is restricted depth to a definition of one-meter contours.
Automatic contouring can only be done when the underlying survey data is of a high-resolution and has been collected via multibeam surveying. The charts produced are then validated within the software to ensure compliance with IHO international standards for ENC production and are subsequently manually checked by a UKHO cartographer to confirm accuracy.
With a greater variety of depth contours within the ENC, the ECDIS can set safety contours at one-meter intervals. This overcomes the safety, alarm and paperwork challenges encountered in this area previously. It reduces stress on the bridge and can give crews more confidence on the approach for the safety of cargo and ship.
One of the other key advantages of ADMIRALTY HD-ENCs is that they can be used by both pilots in portable pilot units (PPUs), as well as by mariners in ECDIS, ensuring that both are using the same official data. Furthermore, these advances in data production require no change in ECDIS software to use – a big advantage for users who have just adopted a fresh set of IHO Presentation Library updates.
The new charts also mean that data collected from this area by the Port of Bristol Authority via multibeam sonar can now be more quickly processed to deliver updates for vessels navigating the channel.
Bringing ADMIRALTY HD-ENCs to the Dover Strait
Following the success of its work in the Bristol Channel, the UKHO is now developing a unique ENC to improve situational awareness and safety for ships transiting the Dover Strait – one of the world’s busiest waterways.
Using data gathered from routine surveys conducted as part of the Civil Hydrography Programme, the ENC will cover areas of the Dover Strait within the UK’s territorial waters, where traffic safety is a critical issue. This area of the seabed is notoriously narrow and complex, with constantly moving sand waves forcing ships to take part in a traffic separation scheme to ensure that they transit safely through the area.
To create this HD-ENC, the UKHO is applying similar techniques to those used for the Bristol Channel, working with billions of bathymetric data points to draw one-meter contours.
The future of digital navigation
With many of the “big-ticket” technologies like fully autonomous vessels still in their infancy, much of the debate in 2018 around shipping’s digital transformation has tended to focus on the abstract and the hypothetical.
However, the work carried out by UKHO in the Bristol Channel and the Dover Strait provides evidence of the ways in which marine geospatial data is already being used to drive continuous improvement throughout the maritime industry.
Taken as a proof of concept, the UKHO’s work on HD-ENCs opens up the opportunity to create similar charts for other areas in UK waters and beyond, paving the way for safer navigation and a deeper understanding of the world’s oceans.
Thomas Mellor BSc, CMarTech, FIMarEST is Head of OEM Technical Support and Digital Standards at UKHO.
The opinions expressed herein are the author’s and not necessarily those of The Maritime Executive.