Active Motion-Compensation Technology for Roll-On/Roll-Off Cargo Vessel Discharge to Floating Platforms

The overall goal of this Phase II project is to develop a motion compensating platform (MCP) technology for the 32MJ Electromagnetic (EM) railgun aboard the Joint High Speed Vessel (JHSV). Ship motion for the catamaran is significantly different from a monohull such as the DDG 51. Both its peak linear and peak angular accelerations will be higher than those for a monohull in high sea conditions. Because the current turret train and elevating actuators of the railgun are not designed to accommodate the higher accelerations and higher frequency contents in the ship motions of the JHSV, the Navy has desired to mount the railgun on an MCP so that the turret train and elevating actuators can function as designed. Specific design objective of the MCP includes reducing the linear accelerations by at least 50%. The MCP will also reduce the higher frequency contents to make them similar to those of an uncompensated monohull. A technology demonstrator of the MCP will be developed and tested using a fire control radar as its payload aboard the JHSV in the summer of 2016. The developed MCP technology is scalable for much larger payload should a requirement for supplemental railgun stabilization emerge.