The Graupner bow thrusters that I have seen are fitted with a 7.2 volt motor.  Run on 12 volts either the motor or the drive will soon suffer, so either change out the motor to a higher voltage version, or run on a separate battery, or calculate a suitable series resistor to calm it down.  Thrusters tend to not be the most accessible items for servicing, so making sure that they have a long life is a good idea.<div>
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