Understanding Load Calculation in Thrusters: Fixed Pitch (FPT) and Controllable Pitch Propellers (CPP) – part 1

In the maritime industry, especially for vessels reliant on Dynamic Positioning (DP), understanding the load characteristics of thrusters, both Fixed Pitch (FPT) and Controllable Pitch Propellers (CPP), is critical for optimizing performance, ensuring safety, and managing fuel efficiency. One common misconception is that a 50% load on a thruster translates to either 50% pitch in CPP systems or 50% RPM in FPT systems. However, in reality, the relationship between load, pitch, and RPM is far from linear and understanding this relationship can significantly enhance operational efficiency.

The Basics of Thruster Load Calculation

In simple terms, the “load” on a thruster is the percentage of its maximum potential thrust or torque being utilized. It reflects the amount of work the thruster is doing relative to its maximum capacity. While this load can be altered by adjusting RPM, pitch, or a combination of both, how each factor influences the load differs significantly between Fixed Pitch and Controllable Pitch Propeller systems.