I have developed a design for a river cleaning machine which can cut and collect weeds. The problem which is facing is how to rotate the circular blade which is attached in front of the machine. I mean first is to directly attach on a dc motor's shaft but there are less to zero options available for waterproof dc motor. Next is to shift the motor to another place and add a chain connection between the motor and the blade.
The black circular spiky thing is the blade which is attached in front of the body.