The tug of project 90600 is intended for towing and berthing operations in harbor, off-harbour and coastal areas which comply with R3 navigation area, refloating of ships and vessels, fire fighting operations at floating and shore objects, oil spill response activities, assisting operations in ports. The tug is equipped with external fire fighting system made by FFS (capacity is 800 m3/h, 2 water monitors, water curtains system). Deck equipment: bow electro-hydraulic anchor-towing-mooring winch Fluidmecanica providing 10 t of bollard pull and 847 kN of brake holding force; 60 t towing hook GMH with quick release device.

Project 90600 tugs from Pella Shipyard bear many similarities to other standard ASD ship-handling tugs and it is easy to overlook what Pella describe as the "distinguishing features" of this class of tug which include: high manoeuvrability; high level of automation and centralisation of control ensuring security and comfort of piloting; operational reliability also in severe ice conditions; all-round view from the wheelhouse; installation of equipment of world leading manufacturers; comfortable compartments for work and rest and ease of operation and finally high economic efficiency.

Tug RB-45 laid down at the Pella Shipyard, Otradny (yard No.927), launched 31 May 2011, commissioned 06 October 2011.

In 2013 the tug was transferred to the General Directorate of deep-sea research (GUGI) of the Ministry of Defense of the Russian Federation, and renamed to Krab. Dipping sonar and container with additional Korvet MK MPD-300 special equipment were added.

Now in service.