# Assessment of Hull and Propeller Degradation Due to Biofouling Using Tree-Based Models
## 3 The Case Study and Preliminary Assessment  
### The Examined Ship and Data Acquisition  
The examined ship is a Kamsarmax-type bulk carrier, with the main characteristics shown in Table 1. A dataset generated by the on-board high frequency data-acquisition system (DAQ) was used, spanning a period of two and a half years, specifically from February 2021 to July 2023. The sampling period was one minute, so it consists of 1,311,000 synchronized datapoints. From the available parameters, 268 were derived for analysis by excluding parameters used by the DAQ provider for internal purposes. When examining the data, it appeared that some parameters were not available throughout the recording period. For instance, draft measurements were valid until November 2021, since after that date the sensors failed and produced faulty values. Available weather provider data started from April 2022. Moreover, the main engine fuel oil supply volumetric flow meter malfunctioned between November 2021 and July 2022, as well as between September 2022 and January 2023, due to mechanical failure. In addition to the high-frequency data, a noon report dataset was available for the same period, consisting of 930 datapoints (Table 2). Even though it contained fewer parameters, in the current analysis, noon reports were used to fill in missing values from the high-frequency data in cases where similar parameters existed. As an example, draft and weather parameters from noon reports were filled in per minute based on their daily values to have the same time resolution as the high-frequency data. By merging these filled in noon report parameters with the original high-frequency data, a new dataset was created. Weather data from a third-party commercial provider had an actual time resolution of one hour. To align these data with the rest of the dataset, the DAQ provider modified the time resolution, converting it to one minute. Available parameters included sea temperature, air pressure and temperature, wind speed and direction, and total current speed and direction. As mentioned previously, while automated logging is certainly more reliable due to the higher frequency and accuracy of the measurements, noon report information was available throughout the examined period, and it was decided to be considered in the cases where high-frequency recording was missing. Having created a dataset containing ship \begin{table}
\begin{tabular}{l l} \hline \hline
**Parameter** & **Value** \\ \hline Length overall & 229.00 m \\ \hline Length between perpendiculars & 225.50 m \\ \hline Breadth, moulded & 32.26 m \\ \hline Depth, moulded & 20.05 m \\ \hline Summer load line draught, moulded & 14.45 m \\ \hline Deadweight at summer load draught & 80,996.1 t \\ \hline Main Engine & HYUNDAI-MAN B\&W—6560 ME-C8.5 \\ \hline Maximum continuous rating (MCRME) & 9930 kW \(\times\) 90.4 rpm \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Main characteristics of the examined ship. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **High-Frequency Data** & **Weather Provider Data** & **Noon Reports** \\ \hline Period & February 2021 to July 2023 & April 2022 to July 2023 & February 2021 to July 2023 \\ \hline Sampling interval & 1 min & 1 h & 1 day \\ \hline Number of points & 1,311,000 & 21,850 & 930 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Basic information about the available datasets. operation parameters from both high-frequency recording and noon reports, the first step of the analysis was to compare the available parameters from both of these sources. Mean draft is calculated as the average of the fore and aft draft measurements. High-frequency draft measurements were valid from February to November 2021. Figure 1 shows the relative frequency distribution of the difference in the mean drafts obtained by the noon reports and the respective mean draft values from the on-board high-frequency sensors during this period.