South Korea's proposal for the Indian Navy's P-75I is based on the Republic of Korea Navy KSS III design
The DSME3000 has a length of 83.5 meters, a beam of 9.7 meters, a draft of 14.7 meters, and a maximum submerged speed of 20 knots per hour. It is based on the Dosan Ahn Changho-class of the Republic of Korea Navy (ROKN) which is being jointly produced by DSME and Hyundai Heavy Industries (HHI) as part of the KSS III program. The class are the largest submarines ever operated by the ROKN. It is armed with six 533 millimeter torpedo tubes and six vertical launch system (VLS) cells. It also has better living quarters and amenities for seamen compared to other ROKN submarines. DSME produced the first two ships of the KSS III Batch 1 which were launched in 2018 and 2020 respectively, while construction on the third ship, by HHI, is ongoing. A total of nine vessels are planned: Three in a “Batch 2” configuration and three more in a “Batch 3”. The local content and capabilities are improved in each batch. For example, KSS III Batch 2 submarines will feature Lithium Ion batteries.
The variant being offered to India will not have the VLS cells that are standard on the Dosan Ahn Changho-class.
“We haven’t finalized the exact design for India, but the removal of the VLS cells behind the sail of the submarine will allow for greater flexibility. We will be able to add new features to meet the Indian Navy’s needs. Moreover, there is a possibility that we will offer submarine rescue vessels alongside our subs as part of a large ‘package’ deal.”
According to the representative, of the five companies shortlisted for the P75I competition, TKMS and DSME are the only contenders that have already designed and produced working fuel cell-based AIP submarines.
“The Dosan Ahn Changho-class uses fuel-cell AIP technology. We believe this will give us the edge,”
Fuel-cell based AIP technology allows non-nuclear submarines to stay submerged for a significant amount of time. The system does not need a battery. As long as it receives a continuous source of fuel, such as hydrogen and oxygen which can be obtained from the ocean, it can continue to operate for an extended period of time. The representative continued, “The exact time period during which the DSME3000 can remain submerged is classified. However I can tell you that it is one of the most capable submarines in this regard.”
Another potential rubric for the P75I competition is the quality of the battery that will equip the submarine. Even if a submarine uses AIP technology, solely relying on it would be inefficient and risky. Therefore, AIP submarines still need batteries to further augment their endurance. These batteries need to be charged while the submarine surfaced or at periscope depth. Traditionally, submarines have used lead acid batteries. However, Japan became the first country to operate submarines equipped with lithium-based batteries when it commissioned the JS Oryu and JS Toryu, the last two Soryu-class submarines, in 2020 and 2021. However Japan is not part of the P-75I competition.
The DSME representative told Naval News at MADEX 2021 that the DSME3000 will also utilize lithium-ion battery technology. “We are the most advanced in this regard amongst our competitors. We created a replica of the submarine’s battery system and completed quality control tests already. We plan on integrating the system into the second batch of Dosan Ahn Changho class submarines as well.” He continued:
“Our lithium batteries are far more efficient than traditional lead-acid ones. This means they don’t have to be charged as often, allowing the submarine to stay submerged for longer. Moreover, they can be charged twice as often before they have to be replaced.”
About India’s P-75I
The Indian government shortlisted in January 2020 two Indian shipyards and five foreign defense companies for the P-75I project which calls for the local construction of six conventional submarines fitted with air-independent propulsion (AIP) systems in a contract worth $7 billion. The programme requires a high degree of localization; all six submarines are expected to be constructed in Indian shipyards.
The two local shipyards that were shortlisted are the privately owned L&T group and state-owned MDL. The five foreign defense companies are: