# Analysis of the Accessibility of the Swinoujscie-Szczecin Fairway for Deep-Draught Ships
## 1 Introduction
### Strategic Role of the Fairway in Maritime Transport  
The Swinoujscie-Szczecin fairway is of significant importance for navigation and maritime trade. It is an important route connecting these two ports with the supply chain on land [1; 2; 3]. These ports are an important part of this chain and allow for the optimization of goods transport to the European market. To ensure the continuity of the transport chain, ships must navigate this fairway safely and efficiently, which requires providing appropriate navigation conditions, such as fairway depth [4; 5] and adequate water levels. Variable water levels are one of the main factors that can affect the movement of vessels [6], directly impacting the ability of deep-draught commercial ships to pass through the fairway without the risk of downtime [7]. The Swinoujscie-Szczecin fairway constitutes one of the key inland-sea waterway connections in the southern Baltic region, linking industrial and logistic hubs in western Poland with global maritime routes. Its dual function--as a deepwater access route for ocean-going vessels and as a transit corridor for inland navigation--places it in a strategic position alongside other estuarine systems such as the Elbe (Germany), Danube (Romania), or Ems (Germany-Netherlands) rivers. Compared to the Elbe, which faces periodic navigation restrictions due to sedimentation and tidal fluctuations in the Port of Hamburg, the Swinoujscie-Szczecin route benefits from predominantly wind-driven variations, though it remains vulnerable to temporary draught limitations during low water events. The results presented in this study contribute to the broader scientific discourse on fairway management by providing a quantifiable method for determining under-keel clearance thresholds based on historical hydrodata. While previous studies have addressed similar challenges in other estuaries, the present approach introduces a simplified yet practical framework applicable to data-rich yet morphologically dynamic waterway systems. There is a wealth of literature on the impact of hydrometeorological conditions on navigation, but few focus on the Swinoujscie-Szczecin fairway, where wind direction and speed, as well as current water levels, are significant factors affecting safe passage. The increasing demand for maritime cargo transport means that larger ships with greater draughts are appearing on the fairway, and planning their passage requires careful management of the fairway and continuous monitoring of water levels. The depth of harbour water and the under-keel clearance of a vessel is a major obstacle in the management of vessels. Their safe passage through the fairway depends on the value of the under-keel clearance (UKC), which is the maximum draught of the vessel during voyages and manoeuvres. In ports, it is the maritime administration, port authorities, and \begin{table}
\begin{tabular}{c c} \hline
**Symbol/Term** & **Definition** \\ \hline \(h_{0}\) & Reference water level—in this study, the Amsterdam Ordnance \\  & Datum (NAP), adopted as 500 cm. \\ \hline \(h\)_(t)_ & Water level at time —actual water level at a given moment, based on observed hydrological data. \\ \hline \(h_{kr}\)(\(T\)) & Critical water level—the minimum water level required for a vessel with draught T to safely enter the fairway, ensuring that UKC \(\geq\Delta\)h. \\ \hline \(P_{\Delta h}\) & Expected number of waiting events per year due to insufficient UKC (i.e., when \(\Delta\)h is exceeded). \\ \hline \(lr\) & Number of port entries per year of “maximum vessels” considered in the analysis (e.g., 100/year). \\ \hline \end{tabular}
\end{table} 
Table 1: _Cont._ship masters who determine the required level of UKC and their objectives and needs may vary, influencing the decision to choose the appropriate UKC. The value of the UKC depends on a number of factors, including provisions for fluctuations in water level, waves, and heeling and settling of the vessel as it moves [8].