By Aidan Morrison*
A couple of months ago Andrew Davies offered some comments (https://www.aspistrategist.org.au/pump-up-the-pump-jet/) on the pump-jet propulsion system that’s proposed as a key feature of the Shortfin Barracuda. As he observed, there seems a clear case for propellers being more efficient at low speeds—which is very important for conventional submarines. Comments from Naval Group’s director of the future submarine program seemingly confirmed this.