RC boat motor, why CW and CCW versions

[Erhy]

Hello,
I search for a motor steered with own ESP32 software.
I would like this:
RC Jet Boot Motor Underwater Thruster 7.4V 16800RPM on https://www.aliexpress.com/item/33031534723.html

but I don't understand why there is a CW and CCW version,
because I think, if I change the polarity, the rotor change the direction.

Thank you for discussion
Erhy

 

[ClydeCrashKop]

They have left hand & right hand props for efficiency.
Real boats are like that. They work a lot better going forward.

 

[JimB]

On boats (and aircraft) with twin propellers, CW and CCW rotation balances out the torque reaction.

JimB

 

[Externet]

Perhaps the threaded shaft direction avoids the propeller securing nut from loosening ?