## 3 Methodology
### Experimental Design and Procedures
We acknowledge that non-balanced sample characteristics may introduce interpretive bias; therefore, we have reported key demographic metrics for transparency. Prior to the commencement of the simulation, all participants completed the PSS questionnaire. They then wore a Polar H10 chest strap to collect HRV data via the Elite HRV application installed on a smartphone. As a backup to the chest strap and for quick visual monitoring of their heart rate data, the participants also wore a Polar Vantage V wristwatch. Both the chest strap and the wristwatch were connected via Bluetooth. Once everything was set up, the scenario then commenced according to the scenarios given in Figure 4 and the selected cases shown in Table 1. The overall scenarios were depicted as follows. \begin{table}
\begin{tabular}{c c c c} \hline
**No.** & **Groups** & **Description** & **N** & **Percentage** \\ \hline
1. & Age & Below 40 years old & 12 & 50.0 \\
2. & & Above 40 years old & 12 & 50.0 \\
3. & & Below 5 years & 3 & 12.5 \\
4. & Experience & 5 to 10 years & 7 & 29.2 \\
5. & & Above 10 years & 14 & 58.3 \\
6. & & Master Below 3000 Gross Tonnage (ANT-II) * & 14 & 58.3 \\
6. & & of Competence (CoC) & Master—Unlimited (ANT-I) & 7 & 29.2 \\
7. & & Master & 17 & 29.2 \\  & & Chief Officer & 7 & 70.8 \\  & & Container & 3 & 12.5 \\  & & General Cargo & 7 & 29.2 \\  & & Coastal Tanker & 5 & 20.8 \\
8. & & Ship Type Experience & Tanker & 5 & 20.8 \\  & & Supply & 2 & 8.3 \\  & & Tugboat & 1 & 4.2 \\  & & Passenger Ship & 1 & 4.2 \\ \hline \end{tabular}  
* ANT is a term used in the Indonesian Certification on Seafarers in Nautical Studies, where ANT-I is the highest.  
\end{table} 
Table 3: Participant demographics. The simulation scenarios were constructed based on AIS-derived encounter data and risk assessments to reflect realistic and high-risk navigational situations commonly faced by seafarers. Each simulation segment was designed to reflect distinct encounter geometries and was completed at the vessel's simulated desired speed set by each participant independently. On average, each segment lasted approximately 8 to 10 min, which served as the effective time window for calculating physiological metrics such as the RR interval, SDNN, RMSSD, and LF/HF ratio. This duration complies with accepted standards for short-term HRV analyses. Figure 4: Design of the scenarios divided into segments, with each participant given the required time in the simulation. Figure 3: Bridge simulator with the captain in the center, one officer, and one helmsman. The simulation environment was set to daylight conditions, with the sea state set to a light breeze (Beaufort scale 2) and the north-easterly wind set to 4-6 knots, with minimal currents. To meet the required time, the distances were limited to 14 nautical miles from the start point to the finish point, and also to exacerbate the simulation, each participant was asked to arrive at the finish point at the exact estimated time of arrival that was set and agreed upon once the simulation began. After completing the simulation, the result of the HRV recording was then processed in Kubios computer software version 4.1.0, and once again all participants were required to fill in the NASA-TLX questionnaire.