Quite a decoy that could mislead Western subs on Russian sub fleet movements:
Russia Developing Robot Able to Imitate Any Submarine
(Source: TASS; published Dec 06, 2016)
MOSCOW --- Specialists of Russia’s Rubin Central Design Bureau for Marine Engineering have developed a conceptual design of a seaborne robotized system called Surrogat for holding naval exercises, the design bureau’s press office told TASS on Tuesday.
Currently negotiations are under way with the Navy on this project, the press office said.
Surrogat is equipped with a lithium-ion battery. This submarine imitator provides for up to 15-16 hours of naval exercises, reproducing an enemy submarine’s maneuvering, including at high speed, over this time.
The robot’s relatively large size (about 17 meters long) and the ability to carry towed sonar arrays for various applications will help realistically reproduce an enemy submarine’s physical fields - acoustic and electromagnetic, the Rubin design bureau said.