This project is part of a largescale campaign consisting of multiple parties working together to present a higher level of understanding of ship emissions in cooperation with the Port of Brisbane Corporation. The AVL BOOST program is employed to model the main engine (ME) of marine vessels which predicts accurate results on the emissions being expelled from the exhaust gas under various operating conditions. Ship’s main marine engine performance and emission data was collected from the large bulk carrier (named Vessel II). This data was analysed and a set of performance values and emission factors were obtained. A numerical simulation was created to simulate the performance data for the Vessel II ME. Investigation was specifically carried out on the prediction of a combustion model that is used to predict the Rate of Heat Release (ROHR) during combustion. The vibe 2 zone function was used as an appropriate mathematical model to simulate the combustion of Heavy Fuel Oil (HFO) within the ME. A method for how the vibe function changes with a changing engine load and engine speed is discussed and a relationship between the vibe function parameters and operating conditions of Vessel II is found.