Abstract: A thief hatch state monitoring system includes a thief hatch sensor that detects a change in angular position of a thief hatch and generates sensor data at an output in response to the detected change. A processor having an electrical input is electrically connected to the output of the thief hatch state sensor. The processor determines when the angular position of the thief hatch changes by more than a predetermined amount from the sensor data and then generates a transmit signal indicating a state of the thief hatch. A network interface is electrically connected to an output of the processor. The network interface generates a signal that indicates the state of the thief hatch. A communication gateway includes a receiver that receives the signal indicating the state of the thief hatch. The communication gateway is electrically connected to a network that provides an end-user remote access to the state of the thief hatch.