The Large Survey Vessels “Heiyo” and “Koyo” Come into Service: Current Status on the Enhancements of the JCG’s Survey Resources

Two large hydrographic survey vessels, “Heiyo” and “Koyo”, were commissioned by the Japan Coast Guard in January 2020 and March 2021 respectively for the first time in almost 20 years. The background of the commission, as well as the current status on the Enhancement of the JCG’s survey facilities, starting with the new hydrographic survey vessels that have state-of-the-art research equipment are presented.

Overview of work performed with the survey vessels and the background to their development

Survey vessels of the JCG Hydrographic and Oceanographic Department (JHOD) perform oceanographic researches in the waters surrounding Japan. The results are used for various purposes, including ensuring navigational safety, conservation of the marine environment, disaster risk reduction, and securing maritime interests.
Among these purposes, to secure Japan’s maritime rights and interests, the JHOD had conducted continental shelf surveys from 1983 to 2008 to extend the continental shelf beyond 200 nautical miles from the baselines of Japan. This action contributed to the establishment of the Japan’s extended continental shelf (ECS).
Amid this situation, China and Republic of Korea argued that the boundary demarcation in the East China Sea be based on the Sea’s geological characteristics. China even argued that the continental crust end at the Okinawa Trough. Therefore, in December 2012, they applied to the Commission on the Limits of the Continental Shelf to extend their shelf into the Okinawa Trough.
The Commission examines applications in the reception order. However, the Commission will defer consideration of these applications, even when their turns have come around. Regardless, China and Republic of Korea are strengthening their oceanographic research facilities, and Japan must collect and maintain more scientific research data.
This situation led to the Policy on Strengthening the Maritime Security System decided at the Ministerial Council on the Strengthening of the Maritime Security System, held in December 2016. Based on this policy, the JHOD decided to strengthen the oceanographic research facilities, primarily through the construction of the survey vessels “Heiyo” and “Koyo”, with the aim to properly assert Japan's position against other countries' applications for ECSs and claims of maritime boundaries beyond the median line.
Alongside the construction of “Heiyo” and “Koyo”, the JCG introduced its first survey airplane (Aobazuku, belonging to the 2nd Regional Coast Guard Headquarters) and autonomous ocean vehicles (AOVs) required to survey the low-tide line, which serves as a baseline for maritime boundaries with other countries. In addition, to optimize the operation of this expanded oceanographic research system, the JCG also enlarged the Survey Ship Operation Office, part of the JHOD’s Administration and Planning Division to establish the Survey Operations Office in April 2020 to operate survey vessels, survey airplane, and AOVs around the clock.

Figure: Location map of the proposed outer limits of extended continental shelf (ECS)
in the East China Sea submitted to the United Nations by China and Republic of Korea

Performance of the survey vessels and onboard observation equipment

The new survey vessels, “Heiyo” and “Koyo”, are designed to conduct high-precision, wide-area hydrographic surveys. Their basic features include noise and vibration control to minimize the impact on precision surveying instruments, low-speed and long-duration navigation capability, and a fixed-point holding capability.
Specifically, these survey vessels employ a combination of four generators and electric propulsion, as well as strengthened soundproofing and anti-vibration measures for the generator motors. Their observation and living areas are separated from noise sources, and they also feature the first use of azimuth propulsion amongst JCG’s survey vessels¹.
With regards to observation equipment, both survey vessels are equipped with three types of multibeam echo sounders with different frequencies and beam angles for shallow water, archibenthic, and the deep sea. The echo sounders can determine water depths up to about 11,000 meters (the deepest part of the world's oceans is the Mariana Trench, at 10,920 meters, making it possible for these echo sounders to survey any part of the world's oceans). They are also equipped with an acoustic Doppler current profiler that uses ultrasound waves to measure the direction and velocity of water currents in the surveyed area and a sub-bottom profiling system to survey the geological structures of sub-surface layers.
In terms of onboard equipment, the “Heiyo” is equipped with cutting-edge equipment for seafloor topographic surveys, while the “Koyo” is equipped with similarly advanced equipment for seafloor geological surveys. The specific contrasts between shipboard equipment are shown in Table 1.
The names of the vessels were chosen from among many candidates submitted by the general public. “Heiyo" reflects a wish for "a calm and peaceful sea through oceanographic research," and "Koyo" for "promoting oceanographic research to elucidate the shining sea by casting a light on parts of the sea that are not yet fully understood.” The ships’ hulls were inscribed with the name “Heiyo” by former Minister of Land, Infrastructure, Transport and Tourism ISHII Keiichi and Koyo by current Minister AKABA Kazuyoshi.
The existing large survey vessels “Shoyo” and “Takuyo” were also upgraded with high-performance surveying equipment. These upgrades were made due to the necessity for surveys to be conducted in the East China Sea and to hasten the development of essential information that will help secure maritime rights and interests.

Table 1: Comparison of primary equipment installed on newly built survey vessels

Heiyo (left, commissioned in January 2020, 4,000 tons) and Koyo (right, commissioned in March 2021, 4,000 tons)

Future expectations and prospects

The situation in the seas surrounding Japan is becoming more severe. Therefore, the whole JCG needs to steadily promote the enhancement of its systems, including maintenance of patrol vessels, survey vessels, and aircraft, in accordance with the 2016 Policy on Strengthening the Maritime Security System.
The “Heiyo” and “Koyo”, which are core to strengthening the oceanographic research system, will engage in conducting surveys on the topography and geology of the seafloor in the Sea of Japan, the East China Sea, and other sea areas, making full use of the cutting-edge equipment and technologies that have been introduced in this article. These survey vessels will play an essential role in securing Japan's maritime interests over the long term.
Furthermore, it is also expected that the information obtained from the surveys is used as base information for future marine utilization and disaster risk reduction. For example, in the past, a survey vessel found a number of chimney-like formations off Kume Island in Okinawa Prefecture, which led to the discovery of high-grade hydrothermal deposits with high metal content².
This year marks the 150th anniversary of the establishment of the Hydrographic Bureau, the former JHOD, in 1871, and the start of Japan's first full-scale hydrographic services, which used modern technologies to perform everything from hydrographic surveys to nautical charts.
Over the years, the specifics of hydrographic services have changed dramatically through incorporating various leading marine technologies. However, the promotion of oceanographic researches and the development of marine information remain indispensable for the navigational safety of vessels and for securing Japan's maritime interests. The JCG will continue to focus on these as a major pillar of its maritime security operations. (end)