BMO (translates as Armored Sea Hunter) was designed and built during the defence of Leningrad, using what was available in a beseiged city. Its hull is welded, with rough straight lines. It's armored with plates salvaged from destroyed light tanks.
Intended role of this craft was a submarine chaser, however it proved very useful for a number of different tasks. Its anti-aircraft armament is quite heavy for a ship this size, making it a useful escort boat for larger ships.