In this issue AMI is featuring submarine modernization insights from our forthcoming article on the conventional submarine industry, scheduled to appear in Germany’s Mittler House publications on defense and security.
AMI identifies 537 submarines and submersible vehicles in active service as of August 2022. Of those, 382 (just over 70%) are conventionally-powered submarines built since 1945. Filtering that count down to submarines displacing 1,000 tons or more, and built since 1982, AMI identifies 249 hulls.
Conventional submarine modernization remains a core element of the submarine construction industry. Often new technologies, construction techniques, and materials are first introduced in refits and upgrades to existing hulls as the fastest path for bringing additional capability to submarine fleets.
One example is composite materials, whose use in submarine construction dates back decades, such as fiber-reinforced plastics in the Type 206A submarines, that entered service in the late 1960s. The weight savings, flexibility, and other production advantages of composites on submarines continue to make them a material of choice. As an example, these materials are being used for parts of the upper superstructure, sail and sonar windows on the Type 209 design. ThyssenKrupp states glass-reinforced plastics (GRP) and carbon-fiber-reinforced plastics (CFRP) are used on the Type 212A and Type 214 submarines now in production, citing their use for large 3D shapes or to meet transparency requirements (sonar). Other applications include life raft containers, torpedo countermeasures launching tubes, rudders, shafts and propellers.
Additive manufacturing is another building technique now being incorporated in submarine component construction, successfully demonstrating the ability to meet higher standards typical in all aspects of submarine building. In 2019 TKMS-HDW received classification society approval to introduce “3D printing” to its manufacturing processes. By July 2020 the company announced that standard parts obtained from the 3D printers were being installed on submarines, specifically citing plastic tube bundle holders, and steel housings for ventilation systems.
In February 2021, Australia’s submarine sustainment provider ASC, DMTC (ex-Defence Materials Technology Center) and the country’s science agency CSIRO announced a teaming agreement to explore how additive manufacturing technology might be applied to repairing damaged metal surfaces on the Royal Australian Navy’s (RAN) Collins class submarines. Specifically, the project will explore the potential of cold spray technologies for local repairs. As ASC is the shipyard most likely to lead local involvement in Australia’s future submarine program, results from this project are expected to be incorporated in future submarine component construction at the facility.
As these techniques and materials gradually make their way into conventional submarine construction, AMI will continue to look to the modernization market space for near-term impact. As the Collins class project suggests, navies are seeking solutions to upgrades, repairs and modernizations that minimize the time a submarine is out of service. This approach also relieves stress on what is a relatively thin submarine construction infrastructure, limited in facilities and skilled workforce. The U.S. Acoustics-Rapid COTS Insertion (A-RCI) is an example of a program that draws on commercial off-the-shelf (COTS) technology for faster and more continuous upgrades of submarine signal processing. While structural and major engineering upgrades are less suited to this “more rapid and more local” approach to modernizing submarine capability, we continue to anticipate industry and fleet operators will seek new technology and materials that optimize the capability and operational availability of generally small and overworked conventional submarine fleets.