Since the 1960s, the importance of marine utilization and development has been pointed out. Various approaches for this purpose have been taken, but the progress remains inadequate. One of the reasons is the lack of infrastructure at sea as a hub. Therefore, marine hub ports should be constructed on remote islands including Minamitorishima Island and Okinotorishima Island to promote marine utilization and development.

However, these remote islands are surrounded by severe sea wave environment and severe sea climate for port construction which are different from those of general ports in main islands. Further technological development is required to ensure smooth ship berthing, cargo-handling, and port construction.

Therefore, in this research theme, we will make maximum use of previously accumulated knowledge regarding waves, sea-bed soils, port structures, and port construction to construct ports on remote islands, and will also promote marine utilization and development. Specifically, we will clarify the characteristics of waves in isolated reef areas, and will develop a new mooring system for ships. We will also develop technologies for downsizing and reducing the weight of underwater acoustic video cameras, as well as utilization and development.

For the development of techniques that can be utilized on mooring facilities constructed in isolated coral reef sea areas, we created a wave height estimation tool that can be applied to the quay walls at Minamidaito Port and Kitadaito Port, using NOWPHAS data observed around Okinawa Island. In addition, we measured the magnitude of motions and the mooring force on vessel models that were moored above an isolated reef in a model experiment, under various mooring and wave conditions; supplemented the results of the model experiment using the improved version of CADMAS-SURF/3D that was developed during the previous fiscal year; and clarified what mooring and wave conditions would allow safe mooring and cargo handling in such sea areas.

For the technological development of a new mooring system for ships in ports, we computed the motions of a ship moored by using the new mooring system utilizing high-strength wire ropes. In the computation, we calculated the maximum wave heights for ship cargo-handling, and verified the effectiveness of the new mooring system by comparing to the conventional mooring method.

For the research on maintenance inspection and investigation technology for remote island ports, we proposed a data management method through which inspection photos captured underwater would be embedded with geotags indicating where those photos were taken and other metadata. In addition, to measure the location data of an underwater vehicle that would be necessary for the management purpose, we proposed a method that would use acoustic positioning equipment, GNSS, a seabed altimeter, and wave pressure gauges in combination. Furthermore, we adapted operation support software and tested it in the actual sea, performing the entire task cycle of deployment, inspection, and recovery, and confirmed that it could be operated with only a small number of workers.

For the research on adaptation of the machine guidance for an underwater excavator, we conducted operation tests at an actual construction site, and identified issues that must be resolved before the technology could be applied to actual use. In addition, we improved external measurement and conducted element testing of attachments for mound leveling. Our aim is to be able to remotely operate underwater backhoes by integrating these technology elements.

For the development of a next-generation acoustic imaging system, we enhanced the performance of an acoustic video camera for shallow sea and achieved water-pressure resistance of 30 m and in-air weight of 32 kg. In addition, we developed / supported to develop a viewing system with additional value something extra, which is chart, blueprint, traverse course, etc., for monitoring construction work, focusing on dredging works, bottom mud replacement works and diver works. Furthermore, we prepared manuals for operating the acoustic video camera and the viewing system.

For the development of analytical methods for the topographic dynamics of carbonate islands, we conducted in situ surveys of Minamitorishima, Naha Port, Hirara Port, and Ishigaki Port, including GNSS survey, photographic survey using drones, multi-beam sounding, water sampling, and aerial photography combining visible light and NDVI cameras. In addition, we collected the geographical feature data of Minamitorishima and analyzed its topographical changes. Furthermore, we examined the relationship between coral growth and environmental conditions, and investigated methods to automatically recognize the distribution of coral-forming organisms and their levels of activity.

As for the study on floating breakwater equipped with wave power generation device, we surveyed the cases of technology development on floating-type wave power generation devices and also the cases of installation of floating breakwaters. We then created the fundamental concept of a floating breakwater equipped with a wave power generation device, based on the results of those surveys.