## 3 A Short Overview of Selected Examples of Measuring and Monitoring Systems on Sea Ships
### Ship Performance Monitoring System
Based on collected data, the ship performance monitoring system can be used for number of standard functions:  
* Data reporting by aggregation, filtering and data grouping with respect to standard (noon, trip, Ship Energy Efficiency Management Plans (SEEMP), Monitoring, Reporting, Verification (MRV) [12], Data Collection System (DCS) for fuel oil consumption of ships) [13] and user defined reports;
* Faults detection in signal sources (sensors' faults or connections' faults) in order to maintain data access;
* Non-optimum operation warnings--system continuously evaluates selected signals according to specialized algorithms in order to recognize situations when vessel or her subsystems are operated  
Figure 2: Scheme of ship to shore data transfer and online access to data with the use of web application. in inefficient manner (e.g., concurrent operation of auxiliary engines at low output which can realized with lower number of units);
* Subsystems' operational performance trending--in order to monitor subsystem performance deterioration and plan maintenance actions (e.g., hull fouling trend or monitoring of main engine specific fuel oil consumption (SFOC) trend as presented in Figure 3[14]. In the monitored time period, an increased value of SFOC index was observed. In order to evaluate main engine performance, the system computes actual SFOC based on momentary fuel consumption and main engine load. Based on additional data collected by the system, actual SFOC is corrected to reference conditions [12; 15; 16]. In parallel, theoretical SFOC in reference conditions is calculated based on data specific for the engine, usually based on results of factory acceptance tests. Finally, difference between actual and theoretical SFOC is plotted as the time trend allowing for detection of gradual engine wear or improper engine tuning);
* Operational optimization--based on actual data and reference model [11] system recommends optimum parameters of operation (e.g., optimum trim with respect to ship draught and speed through the water). Figure 3 presents typical SFOC analyses based on measurements taken onboard during vessel operation. It is visible that data collection is affected by considerable scatter. The reason for this is two-fold: an important factor influencing data scatter is measurement accuracy, secondly, the quality of reference SFOC model also influences results. First factor results in conditions of measurement onboard the ship during her operation. Harsh environmental conditions of ship engine room imply that measurement equipment usually compromise accuracy in order to get required robustness. Especially at low engine load where both fuel flow and shaft power meters operate at low rate, measurement errors are higher. As far as reference SFOC, it is usually obtained during engine shop tests where due to time constraints, only few (sometimes one) load points are exercised. In order to obtain a reference model for complete range of engine, loads interpolation and extrapolation techniques are used which introduce additional error. Despite obvious limitations of this approach, appropriate data processing in long term trending allows for taking practical conclusions. Linearization of time trend (indicated by orange and magenta lines in Figure 3) allows for making predictions of required engine maintenance and thus allowing for better planning. Correlation of rapid SFOC changes with engine tuning actions performed by crew in February 2018 (denoted on Figure 3 by a vertical arrow) in the case of electronically controlled engines allows for evaluation of tuning quality and its impact on engine performance. In this particular case, tuning resulted in drop of specific fuel consumption by \(\sim\)6 g/kWh. Figure 3: Main engine specific fuel oil consumption (SFOC) trend with visible gradual deterioration of engine performance [14]. (Courtesy of Enamor Ltd.).