Hi Alex
Been having a couple of thoughts re this.
Scenario: Line has been cast. Motor reeling line and lure in. Fish bites. Now to stop the line reeling in the fish has to overcome the motor torque and the motor stalls. This will draw a large amount of current from the motor supply with a possible motor burn out.
Before this happens you need to sense the sudden increase in current and switch off supply to the motor. The motor should now be free to turn and become a generator. Load can be applied by connecting a resistor (variable ???) across the motor. As the motor is now rotating in the reverse direction the generated voltage will be opposite in polarity to the supply voltage. By using a suitable diode in series with the load resistor and connecting diode cathode to motor positive and the resistor to motor negative this load can be left in place across the motor and will only come into play when the motor is turned in the opposite direction.
Power can be removed from the motor by using a Mosfet connected as a low side switch and activated by any sensing circuitry used. Or a relay if more convenient. Whatever is used has to latch or you will have a rapid switching on and off of motor power as the current goes off and back on.
Cheers Bob
