Project of a small harbor tug. The harbor tug of project 737 is intended for towing and berthing operations in harbor, off-harbour and coastal areas, oil spill response activities, assisting operations in ports. Harbor tugs is equipped with two Voith Schneider propellers, which significantly increases its maneuverability. Tugs of this project in various modifications served on all fleets of the USSR and later - the Russian Federation. In total, more than 50 harbor tugs of this type were built for the Navy.

Harbor tug RB-44 laid down at the Shipyard No.370 Petrozavod, Leningrad, commissioned in 1963.

Decommissioned in 2019, in September 2019 converted to the target ship with rename to KM-50.