431st Support Vessel Detachment
Identity
The location is best identified as the 431st Support Vessel Detachment of the Russian Navy’s Baltic Fleet, military unit 56058. Independent open-source order-of-battle compilations reviewed place it under the Baltic Fleet’s Kronstadt/Leningrad Naval Base grouping. Registry-derived records for military unit 56058 list an administrative address at Iliikovsky Prospekt 1A, Lomonosov, which indicates the legal address and the operating waterfront are not necessarily the same site. ([vpk.name](https://vpk.name/library/f/dkbf.html?utm_source=openai))
Waterfront footprint
A separately reviewed OSINT location record for the 431st detachment lists three subordinate elements—1st, 2nd, and 3rd Support Vessel Groups—clustered at approximately 29.777E, 59.923-59.926N in the Kronstadt harbor area. That matches the supplied placemark pattern and supports identification of this record as the detachment’s concentrated berthing/operating zone; however, official Russian sources reviewed do not publicly confirm the exact pier-by-pier assignment of those three groups. ([nightwatch.services](https://nightwatch.services/locations/431st%20Support%20Vessel%20Detachment))
Observed function
Official Russian reporting shows tugs from the support-vessel detachment of the Leningrad Naval Base carrying out harbor-assist and towing tasks, including the July 2021 movement of the replica ship Poltava into St. Petersburg for Navy Day events. Official reporting also states that the Leningrad Naval Base received the raid tug RB-60 in June 2022, with declared roles including towing, maneuvering, firefighting, and participation in search-and-rescue operations—functions consistent with a support-vessel detachment based in the Kronstadt support area. ([tass.ru](https://tass.ru/obschestvo/11923539?utm_source=openai))
Parent base and geography
The detachment’s operational context is the Baltic Fleet’s Leningrad Naval Base, whose headquarters are in Kronstadt and whose units are spread across St. Petersburg and Leningrad Oblast. Kronstadt sits on Kotlin Island at the eastern Gulf of Finland approaches to St. Petersburg; the St. Petersburg flood-protection complex incorporates Kronstadt shipping channels and a deepened Kronstadt ship fairway, making this harbor area a protected and logistically useful support node for fleet movements and harbor services. ([tass.ru](https://tass.ru/armiya-i-opk/20241787?utm_source=openai))
Confidence and gaps
As of March 12, 2026, open sources reviewed support the judgment that military unit 56058 is a Baltic Fleet support-vessel detachment tied to the Kronstadt/Leningrad Naval Base support zone. Public sources reviewed do not confirm the exact vessel roster, manpower, readiness level, or the permanent assignment of specific auxiliaries to each of the 1st/2nd/3rd groups; those finer details remain only partially corroborated in secondary OSINT. ([nightwatch.services](https://nightwatch.services/locations/431st%20Support%20Vessel%20Detachment))