The engine that spins the propeller to propel the ship is called the main engine. The most commonly used engine is a diesel engine fueled by heavy oil, which transmits the rotational motion generated by the main engine directly to the propeller shaft to rotate the propeller at the stern. In this case, vibration and noise generated by propeller rotation are transmitted to the hull via the propeller shaft and main engine. To reduce the effect of this (for example, to improve the comfort of passenger ships), an electric propulsion system is sometimes adopted in which the propeller is not directly connected to the main engine but is driven by a motor powered by a generator.  The main engine (and related auxiliary equipment) is located in the engine room at the stern. 

【水産科学・海洋環境科学実習　KAIBUNDO,136-137】

The main engine is the heart of the ship. It is also loaded through an opening in the block. Please take a look at the work of loading the main engine, which is the heart of the ship!