# Maximum Safe Parameters of Ships in Complex Systems of Port Waterways
## 1 Introduction  
### Waterway System in Marine Traffic Engineering  
The sea waterway must be adjusted to the navigation of specific type of ships, characterized by length, breadth, draft and airdraft [1]. The primary requirement for shipping in sea waterways is the safety of navigation [2]. Navigational safety comprises all of the issues related to smooth ship conduct from point A to point B of the sea route.  
The sea waterway system in marine traffic engineering is composed of a number of separate sections (\(n\)). A complex port waterways system is usually composed of the following sections:  
* [noitemsep,topsep=0 pt]
* Approach channel;
* Port entrance;
* A number of straight sections and bends in the fairway;
* Port basins of specific terminals and related turning basins.
* Each of the waterway sections consist of three basic elements [3]:
* Waterway subsystem;Subsystem of ship position determination (navigational subsystem);
* Subsystem of traffic control. These elements affect each other and have an important impact on the system characteristics. Each sea waterway has traffic restrictions for the ships using it [4; 5]. These restrictions are called conditions of sea waterway operation or conditions of ship operation in the sea waterway, and refer to:
* Parameters of ships using the waterway;
* Hydrometeorological conditions, in which, the traffic includes specific types of ships;
* Parameters of vessel traffic intensity in the waterway;
* Conditions of ship maneuvering in the waterway (tug assistance, allowable speeds).  
The conditions for the safe operation of ships in a port regarded as a system composed of various types of waterways are dependent on the conditions of the safe operation of ships in each specific waterway section within the port. The parameters of each waterway within the port determine the conditions of the safe operation of ships maneuvering in that area [6].  
There are a number of empirical, deterministic or probabilistic methods to determine the safe width of maneuvering areas on port waterways [3]. The most important methods include:  
* PIANC;
* ROM (Spanish);
* Japanese;
* CIRM (Centrum Inzynierii Ruchu Morskiego).  
They are widely used, in particular, at the preliminary stage of waterway design. For example, the most widely known PIANC method was used during the initial localization of the LNG terminal in India [7] to determine the approach fairway in the Chinese port of Panjin [8] and to determine the parameters of fairways in Korean waters [9]. However, the use of these methods was limited to determining the parameters of one or a maximum of several types (sections) of waterways (e.g., straight sections, bends, turning basins).  
The direct application of the above methods to determine the conditions for the safe operation of ships on a complex waterway, such as the Swinoujscie-Szczecin fairway, was impossible due to the complexity of the waterway and various restrictions on its individual parts.  
This article:  
* Defines conditions for the safe operation of ships in complex port waterways systems;
* Presents the methodology for determining maximum safe parameters of ships in existing complex port waterways systems.