First ocean survey with synthetic aperture sonar on neutral trim tow-fish

For the purpose of surveying ocean bottom in detail and quickly, Japan Agency for the Marine-Earth Science and Technology developed a neutral trim tow-fish as a stable platform equipped with synthetic aperture sonar. The two patents is applied to the synthesizing process. In August 2010 at Sagami bay, we carried out a sea trial of the SAS on the tow-fish. The motion compensation on the synthesizing worked effectively and the sonar images are stabilized or clear after the process in the trial. In October 2010 at Kagoshima bay, we surveyed a total of 7 km2 area including a mound and a bottom of caldera with the SAS on the tow-fish. We could found hydrothermal vent and bubbles welling out at the mound and the bottom, and unevenness of the caldera was also visible.