What does the Engineering Bell Book document?

The Engineering Bell Book is primarily used to document speed changes of the main engine, specifically in terms of revolutions per minute (RPM). This record is vital for keeping track of how the vessel's speed is altered during various maneuvers or operational conditions. Changes in RPM are directly related to the performance and operation of the main propulsion system, and maintaining an accurate log helps engineering personnel assess the engine's operation over time, monitor trends, and make informed decisions based on previous performance.

While items such as engine maintenance schedules, fuel consumption details, and electrical output readings are important for overall operational efficiency and safety, they are documented in different logs or records. The focus of the Engineering Bell Book is specifically on speed changes, highlighting its importance in understanding and managing the vessel’s propulsion.