# Sensing in Inland Waters to Promote Safe Navigation: A Case Study in the Aveiro's Lagoon
## 2 Advancements in Maritime Technologies: Enhancing Navigational Safety and Communication  
The system presented in this study, which integrates the e-navigation objectives, offers a potential avenue to enhance existing platforms and equipment that facilitate maritime navigation. Indeed, the integration of ICT has led to the development and integration of Big Data and Artificial Intelligence [28; 29], which improve the analysis of information about the vessel, such as Automatic Identification System (AIS) logs, meteorological information, and data acquired from different sensors, to share and compare them with data from other companies and entities [30]. Complementarily, the Internet of Things (IoT) [31; 32] is a relevant technology and, in recent years, has contributed to assisting the maritime sector with ship maneuvers, port management, and aid and rescue [30; 33]. The basis of an IoT system is collecting and sharing information about the electronics installed on the vessels [24; 34; 35], which can aid the sailors' decision-making and improve communication between boats. The rapid advancement of ICT technologies has transformed navigation tools [30; 36; 37], enabling ship-to-land communication, route visualization, access to route information, and the management of collision risks between vessels, all through a single interface [30]. Notwithstanding the numerous benefits of such technologies for the sailors, there are still two main gaps that must be addressed: (i) human error, since sailors may become over-reliant on the system and disconnected from their environment [38; 39; 40], and (ii) the timely sharing of information, such as weather and oceanographic forecasts, namely between communities of sailors, which can contribute to safe route planning [41; 42; 43]. Although many leisure vessels are equipped with useful instruments, improving the communication between sailors and the UI of electronic devices remains essential to ensure distraction-free navigation [44; 45]. Displaying these data on advanced onboard systems, such as plotters, Multifunctional Displays (MFDs), and Electronic Chart Displays (ECDISs), provides crew members with continuous access to critical navigational information [46]. Table 1 summarizes the reasons for checking specific data during maritime navigation, and where and how these data are visualized and integrated into the navigation systems:  
Consider two sailors, A and B (Figure 1). Sailor B acquires the observed depth data while navigating, and Sailor A is interested in understanding the navigability conditions in the same area where Sailor B was located. To facilitate this, the system retrieves the water depth data from Sailor B and sends it to a server, which then calls an API to obtain both past and future tide heights for the area. Using this information, an algorithm processes each of Sailor B's data points, calculating the observed depth relevant to Sailor A [12]. By combining this value with Sailor A's vessel draught, the system is able to display an augmented route. Therefore, both the observed water depth and tide height are critical in this process. Accessing shared meteo-oceanographic data provided by other vessels' electronic sensors (such as anemometers for wind direction and speed, and transducers for water depth), and representing it accurately through a UI that adapts the information collected to the navigational context (i.e., environmental factors-sunlight and rain), reduces risks during navigation [8; 47]. Consequently, the objective of this research is to explore the access to data shared by vessels and use that to aid other vessels. Also, deferred acquisition allows for the analysis of data acquired during a voyage and the subsequent optimization of future routes, thereby contributing to overall maritime safety and efficiency [8; 12; 48]. The sharing of these types of data is also crucial to update or create hydrodynamic predictive models, including input from scientists and experts as well as regular and experienced sailors.