The digital twin of the navigable waters for smart marine navigation

The neologism ‘digital twin’ appeals to our intuitive understanding of a digital replica of real processes. The analogy of the twin creates the idea of great similarity – even if not complete sameness. In fact, this is exactly the point: a digital twin is a virtual representation of a material or immaterial object in the digital world that is as exact as possible. It consists of models, simulations, algorithms and services that describe the properties and behaviour of the real object.

The concept of the digital twin enables communication between the real and virtual object. Data flows from the real to the virtual object, while information flows from the virtual to the real object. By comparing and analysing the deviations between the real and virtual objects, the real objects can be adapted to each other, and processes can be regulated.

This description explains on an abstract level how future intelligent marine navigation solutions will work. If all the data on the condition of the sea areas to be navigated is available in full and can be combined with the help of models, simulations and algorithms to generate an exact digital image of this condition, the optimum route for a ship can be determined, adhered to and continuously monitored. Shipping can interact better with the harbour industry, navigation in marine protected areas can be avoided without loss of efficiency, bad weather areas can be avoided, and autonomous shipping becomes possible.

The vision of who and what the digital twin of the navigable waters can be used for already exists. However, its realization requires the necessary data to be collected, managed and made available for the aforementioned digital tools – models, simulations and algorithms – correctly and in full on a permanent basis. Building on this, there must be smart functions that generate an overview of the current navigational situation and the resulting instructions for action without human intervention.

The generation and ongoing updating of the data is the most complex element here – to manage, process and make it available for virtual representation, it must be technically standardized so that all computers in the chain read and interpret the data in the same way.

For a digital twin to be more than just an overlay of various data sets (like seabed topography, water depths, coastal outlines, currents, weather patterns, and harbour traffic in shipping), the data streams must be integrated in a way that allows algorithms to interpret their relationships – tasks that are still largely reliant on the sailor's expertise and experience. Of particular interest to shipping is route optimization, taking into account weather, tidal and current conditions as well as the water levels to be expected when calling at ports, which would make it possible to maximize the cargo to be transported.

To enable the required intelligent combination of all information, the various topics represented by data must be structured in the same machine-readable way. In other words, they must be subject to an identical semantic model. This is the approach taken by the S-100 concept, which already bears this similar structuring of all data in its name: S-100 Universal Hydrographic Data Model. All data streams that are structured according to this universal model ‘understand’ each other in terms of content. The map apps installed on every mobile phone are a good example to illustrate the added value this creates. Users can plan a route without any special technical knowledge and decide whether to travel by car, train or on foot. They can find out whether there is an open petrol station along the route and whether there is a bistro or a place of interest that is worth a stop. The system automatically warns of traffic jams and suggests alternative routes, the length of which is calculated and compared with the originally selected route. All of this is based on constantly updated data streams on various topics that are standardized and linked to each other in the manner described. The S-100 data model for the maritime sector offers this approach in a framework based on ISO standards for geodata. S-100 is open source, free of charge and continuously expandable.

The core element of S-100 makes it possible to generate data product descriptions for the various topics, which can be easily compared with the small assembly descriptions of Lego kits. The building blocks themselves are standardized, but they can be put together to form a wide variety of elements – for example houses, aeroplanes or a castle. However, unlike the assembly descriptions of Lego kits, the S-100 building instructions for data products exist digitally. Their building blocks are not physically present, have no studs or colours, but are stored in an internet-based library as digital building elements called ‘features’. The features are assigned certain properties called ‘attributes’, which individualize the features. One advantage of this concept is its expandability: if new features with different properties are needed, they are defined in accordance with the applicable basic standards, as in the physical Lego world, and registered in the online library known as the ‘registry’. An alternative analogy for describing data products would be that of containers, whose external dimensions and the way in which they are loaded with various goods are strictly standardized.

The IHO has set itself the goal of developing a series of S-100-compliant data product definitions ready for use by the end of 2024. Priority will be given to those data products that are most important for route tracking. Many major IHO Member States have already committed to operating regular data services to deliver this data to the shipping industry from 2026:

If such data services are available with sufficient supraregional coverage in high quality and secure transmission, the development of smart functions for navigation at a previously unattainable technical level will be of interest to the marine equipment industry. The IHO is working closely with the CIRM, the association of manufacturers of marine navigation systems, among others. Further standardized digital elements of the S-100 universe are required for the implementation of the technical concept from data generation to data transmission and data utilization for smart marine navigation denominated by IMO as e-navigation, and are also being jointly developed:

The first phase of the rollout of S-100 compliant data services will end in 2029 when S-100 compliance becomes mandatory for all new ECDIS systems. Further thematic data services are then expected to be available in a second phase.

In retrospect, it was clumsy to explicitly address hydrography in the official name of the S-100 model. Today, S-100 would probably be called the ‘Universal Marine Geodata Model’. This would be appropriate, because other maritime sectors are now also planning to generate datasets in compliance with the S-100 standard. The following cooperation partners should be mentioned here:

In contrast to the hydrographic products in the narrower sense, the IHO still has a special task in enabling and coordinating these data streams in connection with the data producers. To stay with the analogy used earlier: it is not enough to define the data containers, but an incentive must be created for those who are able to regularly fill the containers and send them on their journey. This system can only succeed in close cooperation with the relevant international bodies and the industry, which must produce the tools for generating the data streams, set up regular data service provisions and define the benefits for all market participants.

When these data deliveries come together in the user’s end applications, where they are read and combined by smart software, they create the conditions for the digital twin of the navigable waters, which can then achieve in the maritime sector what we know today from car navigation and air traffic control. S-100-based systems will fulfil the expectations we are familiar with from land-based applications: we do not want to deal with the complex technical processes running in the background. Instead, we expect simple operation, comprehensible displays and reliable recommendations for action. In the final stage, these recommendations will be automatically executed as smart marine navigation and we will have sea transportation that is safe, efficient and gentle on people, nature, ships and cargo.