Originally designed for The Imperial German and later Nazi German Kriegsmarine (Navy), ''R''-Boats (Raumboote) were Minesweepers that also became multi-purpose Vessels. Over 400 such Craft were built between 1929 and 1944. Later in World War II, many ''R''-Boats were used for Coastal Defense (not unlike a Coast Guard) and for special operations (such as part of The Kreigsmarine ''K-Vernand'' (or Small Boat Battle Units). Unlike The German ''E''-Boat (Fast Attack Torpedo Vessels), ''R''-Boats were somewhat larger and varied in overall tonnage. They ranged from 60 yo 160-tons displaced. Typically, they were roughly 140-feet in length with a Beam of only 20-feet (height). Diesel Engines gave The ''R''-Boats around 1,800-HP in open Sea.
Armament also varied greatly, with a standard 1.5-inch Deck Cannon the primary armament. Some included Deck Machine Guns – with Mines and Torpedo packages also used. They could hold up to 40 Officers and Men. Very maneuverable, The ''R''-Boat design was so craftworthy, that many that were not destroyed (captured in Ports in 1945), were pressed into continued Service with many World Navies (in service as late as the mid-1960s).