Russian small naval vessel sighted near the Leningrad lightship according to a CIA report dated 15 March 1957

An item dealing with the observed activities period between 21 November-1 December 1956 reported that a small naval vessel was sighted going westward near the Leningrad lightship and was described as having a length varying between 120-150 feet, fitted out with one mast an one funnel and fitted out with depth charge chutes on her aft deck.

Source
The report was published on www.archive.org, document number CIA-RDP80T00246A033200070001-5