We are finalizing the design of a counter‑rotating underwater thruster that uses two coaxial propellers that spin in opposite directions (driven by concentric shafts and a dual‑motor setup). The first prop adds thrust but also imparts swirl to the wake; the second prop turns the other way to remove that swirl and recover energy, producing extra thrust while canceling reaction torque on the vehicle.

Why use it

Higher efficiency/ thrust density: better energy recovery in the prop‑wash, useful for compact AUV/ROV thrusters and high‑thrust “bollard” conditions.

No net torque on the hull: reduces unwanted yaw/roll and eases mounting.

Improved controllability: less coupling between throttle changes and vehicle attitude.

In short, it’s a compact way to get more thrust with less torque reaction, at the price of a second motor and prop.