Choosing a gearbox for 56104motor

Hi, everyone, please help in choosing gearbox, I already have sss56104 790kv, and 70mm jetdrive with 3 blades propeller (25mm step), 2 lipo batteries 10ah 6s and esc ZTW seal 300A.
In whater after 20sec motor is heating and i fell smell, I see some ways it’s decrease step of propeller, or choose a gearbox, please help )

Just use a torqedo gearbox and a prop overwise