Which thruster design is more efficient when both thrusters have the same power rating and propeller diameter?

The efficiency of thruster designs, particularly when they have the same power rating and propeller diameter, can significantly depend on the width of the blades. A thruster with narrower blades tends to have less drag and can create a higher thrust-to-drag ratio compared to one with wider blades. This allows the thruster to convert more of its input power into useful thrust, making it more efficient in operation.

Narrower blades can also improve performance in terms of cavitation and stalling, especially at varying speeds or under different operating conditions. With lower resistance in the water, these designs allow for better maneuverability and less fuel consumption, which is critical for dynamic positioning applications.

In contrast, wider blades may provide greater thrust at low speeds, but they often create more drag and can lead to decreased efficiency when overall propulsion and maneuverability are considered. The other options, such as a larger motor or a dual propeller setup, may introduce other variables that do not inherently provide the same efficiency benefit compared to blade width in this specific configuration of equal power and diameter. Thus, the design with narrower blades stands out for its efficiency gains under the stated conditions.