One of the technologies to realize energy saving ship operation is reduction of the frictional resistance of the ship's hull using an air lubrication method. For the first time in the world, Oshima Shipbuilding Co., Ltd., Nippon Yusen Kabushiki Kaisha and Monohakobi Technology Institute will be performing testing of frictional resistance reduction of the hull of an actual ship, a 90,000 ton class vessel of using the main engine scavenging air bypass air lubrication method. The existence of bubbles has previously been detected using an underwater camera, but it is difficult to carry this out continuously over a long period due to the turbidity of seawater. In order to check for bubbles continuously during operation, JRC has developed the "AWA System" (bubble detection system) to confirm the existence of bubbles from the bow to the stern. This report introduces this system, in which multiple echo sounding sensors, commonly used on merchant ships, are mounted on the bottom of a ship.