1. A gyrocompass modeling and simulation (GMSS) system for a gyrocompass, comprising: a computer executing the following simulators and modules; a six-degrees-of-freedom (6DOF) motion simulator; an inertial measurement unit (IMU) sensor simulator; a gyrocompass system and calibration process simulator; a gyrocompass system evaluation and analysis module, wherein said 6DOF motion simulator, said IMU sensor simulator, said gyrocompass system and calibration process simulator, and said gyrocompass system evaluation and analysis module are interlinked via an accumulative communication stream; and a translational motion simulator communicated with said IMU sensor simulator, wherein said translational motion simulator comprises: an input device for inputting a motion command, a stochastic process generator generating a stochastic force signal, a translational motion controller generating a control command and combining said control command with said stochastic force signal in order to form a total force signal, a mass module producing an acceleration data in response to said total force signal, and an integral module producing a velocity data in response to said acceleration data and producing a position data in response to said velocity data, wherein said acceleration data, said velocity data, and said position data are sent to said IMU simulator.