Abstract:
This research was motivated by the importance of the freshwater cooling system in
maintaining the stability of the main engine operating temperature under optimal
conditions. The problem that occurred on board MT. Kei was the increase in cooling
water temperature reaching approximately ±90°C, exceeding the normal operational
limit of 75°C–85°C. This study aimed to analyse the causes of the non-optimal freshwater
cooling system and determine corrective actions. The research method used was
descriptive qualitative with data collection techniques consisting of observation,
interviews, literature study, and documentation. The data were obtained directly while the
researcher worked as a Fourth Engineer on board MT. Kei from 03 February 2025 to 25
December 2025. The results showed two main problems in the cooling system. First, the
sea water system did not operate optimally due to blockage of the sea water strainer by
mud, plastic waste, and moss, as well as low seawater pump pressure of only ±1 bar
caused by impeller wear. In addition, the temperature controller did not function
optimally in regulating cooling circulation. Second, the heat exchanger plate did not
function properly due to fouling on the plate surface and the non-optimal implementation
of the Planned Maintenance System (PMS). Corrective actions included routine cleaning
of the sea water strainer, maintenance of the temperature controller, cleaning of the heat
exchanger, and consistent implementation of PMS. As a result, the cooling water
temperature returned to the normal range of 75°C–85°C, improving main engine
performance and minimizing the risk of damage.
