Developments in underwater technologies — Indian scenario

With a large coastline of approximately 7600 km surrounded by two major ocean basins on both sides of peninsular India as Bay of Bengal and Arabian Sea, drained by major river basins from Himalayas, there are multidimensional requirement of underwater technologies to cater the country´s demand. With increased thrust on underwater technology in India during the past 15 years, it is imperative to put forth India´s development in the frontier area of underwater technologies. Under the Ministry of Earth Sciences, Government of India, National Institute of Ocean Technology (NIOT) is leading the frontier areas of underwater technologies. The Institutes like Central Mechanical Engineering Research Institute and Indian Institute of Technologies are also contributing in a minor way. Under International Seabed Authority (ISA) regulations, Government of India registered as a contractor on 17th August 1987. India was allocated 150,000 sq. km area in Central Indian Ocean Basin for exploration of manganese nodules. After detailed exploration, 50% of this area has been relinquished to the ISA. While other Institutes in India are responsible for metal extraction, NIOT is responsible for developing technology for mining of manganese nodules from the deep seabed. To harness the non-renewable resources ranging from placer deposits at water depth of 100 m, gas hydrates at 1000 m, hydrothermal sulphides at 3000 m to polymetallic nodules at 5400 m water depth, various technologies were developed and proven in the field. To cater to the disaster management, range of observation systems, drifters and seafloor based observations are being developed and data collection and dissemination is in place. This paper deals with the achievements in the development of underwater vehicles and systems during the past 15 years in India in the civilian front. The major technologies developed, like the Deep sea crawler (512 m) for mining of manganese nodules, In-situ soil tester (5462 m) for measuremen- of in-situ soil property on the sea bed, Work Class Remotely Operated Vehicle (5289 m) for general purpose, including assistance in nodule mining, Autonomous Underwater Vehicle (200 m) for shallow water and operation in polar regions, being developed, and drifter buoys for collection of ocean data are explained in detail. The challenges involved in design, development, testing and issues faced during the sea trials of the various systems and lessons learnt are explained in this paper.