A fully interactive dynamic simulation of a semi-submersible towing a large towfish

ISER and DREA are collaborating on the development of SIMRNIS, a fully interactive nonlinear submersible/cable/towfish six degree-of-freedom (DOF) time domain simulation. This capability is not found in standard tow system codes. SIMRMS is a meshing of the DREA Submersible Simulation Program (DSSP) and the DYNTOCABS tow cable/towfish simulator. DSSP is a nonlinear 6 DOF vehicle simulator that models control, propulsion, and ballasting. DYNTOCABS provides a three-dimensional, nonlinear, 3 DOF, finite segment simulation of the cable and includes a nonlinear 6 DOF model of an active towfish. The two programs have been merged so that the equations of motion for all system components are simultaneously integrated in time. New features and capabilities have also been developed. SIMRMS is used as a test bed to minimize technical risk for further development of a remote minehunting system. This paper discusses, and presents full scale sea trials data validating, the program's capabilities.