We proposed to test, design, and modify an existing X-Array tetrahedral (3-D) hydrophone array prototype and design with the ultimate goal of developing a production prototype called the X-3D Array. We will analyze field data collected previously from the first prototype, conduct hydrodynamic modeling of the array design, and research possible torque imbalances in the tow-cable, and use this information to make the necessary design changes to resolve the noise and twisting issues identified in the first prototype. We will then conduct field tests of the new X-3D Array to ensure it is meeting the necessary technical and operational specifications, such as towing it at 10 knots. We will consider the materials and fabrication processes throughout this process so that a production prototype will be ready for Phase II. We have chosen this accelerated approach because an initial prototype already exists. We have assembled a team of world renowned technical experts from the Scripps Institution of Oceanographys Marine Physical Lab. Desert Star Systems LLC will provide guidance on the commercialization aspects of this effort. Bio-Waves Inc., a small business specializing in passive acoustic technologies, will oversee the project management and field testing aspects of the effort.