Motor stall circuit

[Polly1]

Hi. I am designing a circuit to replace a defective one in a boat autohelm. It has to turn off a motor when it is stalled. There is a 2 ohm resistor between the motor and ground. At stall the voltage rise from 0.2 to 0.5 volts over this resistor due to the increased current. I am using a comparator op map set to a potential divider on one of the inputs with this voltage on the other to give a low result at stall. This will be fed to the base of a transistor that is switching the motor current.
Problem is the op amps are not great and only dropping to 2 volts as their low. I have ordered some more rail to rail type ones but they wont be here for a week.
Is there a better way to solve this?
Cheers
Guy